The process of transferring the amine group from one amino acid to another is called

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Hint: Transaminase, a category of transferases enzyme, catalyses this process. This enzyme is also known as aminotransferase as it is involved in the transfer of the amino group.

Complete answer:
Reductive amination is a chemical process in which conversion of a carbonyl group to amine group takes place. The intermediate for this reaction is an imine. The carbonyl group refers to any aldehyde or ketone group.
Transamination is a chemical process in which transfer of an amino group from one amino acid takes place and that amino group is transferred to the keto group of a keto acid.

Deamination, a chemical reaction, in which there is a removal of an amine group from an amino acid, takes place.
oxidative deamination is a chemical process in which formation of alpha-keto acids take place from amine containing compounds.
Amine group is the -NH$_2$ group of an amino acid and keto group is the C=O of the carboxyl group of an amino acid.

So, here the correct answer is option C. Transamination.

The process of transferring the amine group from one amino acid to another is called

Note: One amino group from one amino acid and one carboxyl group from the previous amino acids react to make a peptide bond and as a result water is released. The peptide bond is also called keto-amine bond.

Transamination is the process by which amino groups are removed from amino acids and transferred to acceptor keto-acids to generate the amino acid version of the keto-acid and the keto-acid version of the original amino acid.

From: Human Biochemistry, 2018

Protein and Amino Acid Metabolism

N.V. Bhagavan, Chung-Eun Ha, in Essentials of Medical Biochemistry, 2011

Transamination–Aminotransfer Reactions

Transamination reactions combine reversible amination and deamination, and they mediate redistribution of amino groups among amino acids. Transaminases (aminotransferases) are widely distributed in human tissues and are particularly active in heart muscle, liver, skeletal muscle, and kidney. The general reaction of transamination is:

The process of transferring the amine group from one amino acid to another is called

The α-ketoglutarate/L-glutamate couple serves as an amino group acceptor/donor pair in transaminase reactions. The specificity of a particular transaminase is for the amino group other than the glutamate. Two transaminases whose activities in serum are used as indices of liver damage (Chapter 7) catalyze the following reactions:

The process of transferring the amine group from one amino acid to another is called

All of the amino acids except lysine, threonine, proline, and hydroxyproline participate in transamination reactions. Transaminases exist for histidine, serine, phenylalanine, and methionine, but the major pathways of their metabolism do not involve transamination. Transamination of an amino group not at the α-position can also occur. Thus, transfer of a δ-amino group of ornithine to α-ketoglutarate converts ornithine to glutamate-γ-semialdehyde.

All transaminase reactions have the same mechanism and use pyridoxal phosphate (a derivative of vitamin B6; Chapter 36) (see website for more information).

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Protein and Amino Acid Metabolism

N.V. Bhagavan, Chung-Eun Ha, in Essentials of Medical Biochemistry (Second Edition), 2015

Transamination–Aminotransfer Reactions

Transamination reactions combine reversible amination and deamination, and they mediate redistribution of amino groups among amino acids. Transaminases (aminotransferases) are widely distributed in human tissues and are particularly active in heart muscle, liver, skeletal muscle, and kidney. The general reaction of transamination is

The process of transferring the amine group from one amino acid to another is called

The α-ketoglutarate/L-glutamate couple serves as an amino group acceptor/donor pair in transaminase reactions. The specificity of a particular transaminase is for the amino group other than the glutamate. Two transaminases whose activities in serum are used as indices of liver damage catalyze the following reactions:

The process of transferring the amine group from one amino acid to another is called

All of the amino acids except lysine, threonine, proline, and hydroxyproline participate in transamination reactions. Transaminases exist for histidine, serine, phenylalanine, and methionine, but the major pathways of their metabolism do not involve transamination. Transamination of an amino group not at the α-position can also occur. Thus, transfer of a δ-amino group of ornithine to α-ketoglutarate converts ornithine to glutamate-γ-semialdehyde.

All transaminase reactions have the same mechanism and use pyridoxal phosphate (a derivative of vitamin B6; Chapter 36). Pyridoxal phosphate is linked to the enzyme by formation of a Schiff base between its aldehyde group and the ε-amino group of a specific lysyl residue at the active site and held noncovalently through its positively charged nitrogen atom and the negatively charged phosphate group (Figure 15.5). During catalysis, the amino acid substrate displaces the lysyl ε-amino group of the enzyme in the Schiff base. An electron pair is removed from the α-carbon of the substrate and transferred to the positively charged pyridine ring but is subsequently returned to the second substrate, the α-keto acid. Thus, pyridoxal phosphate functions as a carrier of amino groups and as an electron sink by facilitating dissociation of the α-hydrogen of the amino acid (Figure 15.6). In the overall reaction, the amino acid transfers its amino group to pyridoxal phosphate and then to the keto acid through formation of pyridoxamine phosphate as intermediate.

The process of transferring the amine group from one amino acid to another is called

Figure 15.5. Binding of pyridoxal phosphate to its apoenzyme. The carbonyl carbon reacts with the ε-amino group of the lysyl residue near the active site to yield a Schiff base. Ionic interactions involve its positively charged pyridinium ion and negatively charged phosphate group.

The process of transferring the amine group from one amino acid to another is called

Figure 15.6. Mechanism of the first phase of transamination. The –NH2 group from the amino acid is transferred to pyridoxal phosphate, with formation of the corresponding α-keto acid. The second phase occurs by the reversal of the first phase reactions and is initiated by formation of a Schiff base with the α-keto acid substrate and pyridoxamine phosphate. The transamination cycle is completed with formation of the corresponding α-amino acid and pyridoxal phosphate.

Pyridoxal phosphate is also the prosthetic group of amino acid decarboxylases, dehydratases, desulfhydrases, racemases, and aldolases, in which it participates through its ability to render labile various bonds of an amino acid molecule (Figure 15.7). Several drugs (Figure 15.8) inhibit pyridoxal phosphate-dependent enzymes. Isonicotinic acid hydrazide (used in the treatment of tuberculosis) and hydralazine (a hypertensive agent) react with the aldehyde group of pyridoxal (free or bound) to form pyridoxal hydrazones, which are eliminated in the urine. Isonicotinic acid hydrazide is normally inactivated in the liver by acetylation; some individuals are “slow acetylators” (an inherited trait) and may be susceptible to pyridoxal deficiency from accumulation of the drug. Cycloserine (an amino acid analogue and broad-spectrum antibiotic) also combines with pyridoxal phosphate.

The process of transferring the amine group from one amino acid to another is called

Figure 15.7. Labilization of bonds of an amino acid bound to pyridoxal phosphate-containing enzymes. Given the appropriate apoenzyme, any atom or group on the carbon atom proximal to the Schiff base can be cleaved.

The process of transferring the amine group from one amino acid to another is called

Figure 15.8. Structures of compounds that inhibit pyridoxal phosphate-containing enzymes.

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Pyridoxal Phosphate

M.D. Toney, in Encyclopedia of Biological Chemistry (Second Edition), 2013

Transamination

Transamination is the most common reaction type catalyzed by PLP-dependent enzymes. It is a biologically important process by which living cells reversibly transfer the amino group from an amine (e.g., γ-aminobutyrate) or α-amino acid (e.g., aspartate) to an α-keto carboxylic acid (e.g., α-ketoglutarate). (Figure 2). In the human body, aminotransferases catalyze many different steps in pathways for the biosynthesis and breakdown of amino acids. For example, glutamic acid can donate nitrogen to α-keto acids to form amino acids such as alanine and aspartic acid.

The process occurs via two half reactions. In the first, the amino group is transferred from the amine or amino acid to PLP to form PMP. In the second, the amino group from PMP is transferred to the α-keto acid (Figure 2). During the reactions, PLP and PMP are held tightly in the active sites of the enzymes. Transamination proceeds through covalent substrate–coenzyme intermediates known as ‘aldimines’ (Figure 3) and ‘ketimines’. Formation of the covalent external aldimine between the substrate and PLP allows the electrophilic pyridine ring to stabilize, by resonance, carbanionic intermediates formed on the substrates.

The process of transferring the amine group from one amino acid to another is called

Figure 3. The variety of reactions catalyzed by PLP-dependent enzymes. The bonds, atoms, and reaction arrows are color coded to indicate those involved in each reaction type.

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Amino Acid and Heme Metabolism

John W. Pelley, in Elsevier's Integrated Review Biochemistry (Second Edition), 2012

Branched-Chain Amino Acid Degradation to Succinyl-Coenzyme A and Acetoacetyl-Coenzyme A

Transamination of leucine, isoleucine, and valine (branched-chain amino acids) yields branched-chain α-keto acids. This is followed by oxidative decarboxylation of these α-keto acids by branched-chain α-ketoacid dehydrogenase multienzyme complexes, which are similar to those that catalyze pyruvate and α-ketoglutarate oxidation. Valine and isoleucine are converted to succinyl-CoA, and leucine is converted to acetoacetyl-CoA (see Fig. 12-6).

Pharmacology

Histamine

Histidine decarboxylase produces histamine directly from histidine. Histamine is a potent vasodilator and is released by mast cells during the allergic response. This autacoid relaxes smooth muscles in the blood vessels and contracts smooth muscle in bronchi and gut. Many allergy medications block the binding of histamine to its H1 receptor, preventing vasodilation and capillary permeability.

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Metabolism of Amino Acids

Gerald Litwack Ph.D., in Human Biochemistry, 2018

Transamination

Transamination is the process by which amino groups are removed from amino acids and transferred to acceptor keto-acids to generate the amino acid version of the keto-acid and the keto-acid version of the original amino acid. The reactions are highly reversible, and the forward or reverse direction depends upon the concentrations of substrates or products. This class of enzymes contains pyridoxal phosphate as coenzyme, although certain transaminases (also termed aminotransferases) can use pyruvate as in glutamate-pyruvate transaminase:

glutamate+pyruvate⇌alanine+α-ketoglutarate

Alpha-ketoglutarate is sometimes written as 2-oxoglutarate.

Aspartate aminotransferase is an important enzyme across many species and catalyzes the reaction:

L-aspartate+α-ketoglutarate⇌oxaloacetate+L-glutamate

There are two different forms of this enzyme (different primary amino acid sequence), one residing in the mitochondrion and one in the cytosol (soluble cytoplasm). The enzyme also has been named glutamate-oxaloacetate transaminase, and the two forms have been referred to as s-GOT and m-GOT (see Chapter 3: Water, pH, Buffers and Introduction to the General Features of Receptors, Channels, and Pumps). In Fig. 13.6 is shown the general reaction mechanism for a transaminase.

The process of transferring the amine group from one amino acid to another is called

Figure 13.6. A general transamination mechanism. The coenzyme, pyridoxal phosphate (PLP), attaches to the apoenzyme (enzyme lacking coenzyme or cofactor) through an ε-amino group (ε=epsilon) of a lysine residue in the active site, as shown in the second top left structure; this linkage is known as a Schiff base (aldimine). The orange color represents the first amino acid added. The first ketimine intermediate is formed (third structure, top). The ketimine intermediate is formed followed by the release of the first keto-acid derived from the first amino acid (orange structure on far right) and the formation of pyridoxamine phosphate (structure on right, middle). The second keto-acid (green) is added to form the second ketimine derivative (aldimine, green) and, in the final step, the amino acid derived from the second keto-acid is released (bottom, left in green).

Reproduced from http://www.nd.edu/~aserriann/transam.html.

Muscle cells rely on glutamate-pyruvate transaminase to produce alanine from pyruvate and an amino acid so that the keto-acid produced (like α-ketoglutarate) can be used as fuel for the TCA cycle for the production of energy as ATP. The alanine is carried to the liver in the bloodstream so that the amino groups from amino acids can be converted to urea in the urea cycle. In this way, muscle cells can use amino acids as energy sources while relying on the liver to deal with the amino groups (as ammonium ions). Alanine, a predominant amino acid in proteins, is also transported in the bloodstream to the liver where it can be converted to glucose. Transamination of alanine to pyruvate allows pyruvate to form glucose through the gluconeogenic pathway. The amino group of alanine is attached to α-ketoglutarate through transamination into glutamate. The amino group of glutamate is removed as NH4+ by glutamate dehydrogenase for incorporation into urea that is cleared through the kidney. These reactions are known as the alanine cycle, summarized in Fig. 13.7.

The process of transferring the amine group from one amino acid to another is called

Figure 13.7. The alanine cycle. GPT, glutamate-pyruvate transaminase (also known as alanine transaminase, ALT); TCA, tricarboxylic acid cycle; α-KG, α-ketoglutarate.

During stress, especially prolonged stress, the adrenal cortex secretes cortisol. Even in short events of stress, there is enough cortisol secreted to increase the level of circulating glucose (~10% increase) that evokes a release of insulin. Prolonged stress results in the breakdown of the musculature releasing amino acids into the bloodstream, of which alanine is predominant because of its plentiful occurrence in many proteins. Increased [alanine] is taken up by the liver where it can be converted to glucose (alanine cycle) and, under the influence of insulin, can be converted to glycogen.

Another important enzyme is γ-aminobutyric acid (GABA, also 4-aminobutanoic acid) transaminase. GABA is a key amino acid in the central nervous system, being the main inhibitory neurotransmitter. Although it is technically an amino acid, it is not incorporated into protein. It is an excitability factor, operating through GABA receptors, in the nervous system, and GABA can be acted upon by GABA transaminase:

α-ketoglutarate+4-aminobutanoicacid⇌glutamate+succinicsemialdehydesuccinicsemialdehyde→succinicacid(oxidation reaction)→TCAcycle→energy

This enzyme is one control on the GABA concentration, and GABA can be converted to a form that serves as an energy source. Moreover, the glutamate produced in the reaction also can be converted back to α-ketoglutarate (e.g., glutamate-oxaloacetate transaminase) that can enter another round of GABA transaminase activity, or it can enter the TCA cycle to serve as an energy source.

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Cells, Synapses, and Neurotransmitters

Joseph Feher, in Quantitative Human Physiology, 2012

Glutamate and Aspartate Are Excitatory Neurotransmitters

Transamination reactions in neurons, as well as most other cells, readily interconvert glutamic acid into aspartic acid, and vice versa. Both of these amino acids stimulate the same receptors, and because of the difficulty in distinguishing neurons that use glutamate from those that use aspartate, we classify neurons that use either as a group, the glutamatergic neurons. The glutamate in these neurons derives from α-ketoglutarate in the Kreb’s Cycle, or from ingested food. The neurons store it in synaptic vesicles and release it into the gap when an action potential invades the nerve terminus. All of the receptors on the post-synaptic cell are ionotropic (see Figure 4.2.13).

The process of transferring the amine group from one amino acid to another is called

Figure 4.2.13. Handling of glutamate at glutamatergic synapses. Glutamate is synthesized from glutamine by glutaminase in the pre-synaptic terminal. The glutamic acid is stored in synaptic vesicles and released in response to an action potential on the pre-synaptic membrane. The released glutamic acid binds to one of its receptors, either the NMDA, AMPA, or kainate variety. Each of these incorporates ion channels and binding of glutamate increases the conductance to some cation, producing an inward current and an EPSP. The released glutamic acid is taken up by glial cells and resynthesized into glutamine by glutamine synthetase.

The NMDA receptor, named for an artificial agonist, N-methyl-d-aspartate, increases gCa, the conductance to Ca2+, in response to glutamate binding. The increased gCa produces an inward current that depolarizes the post-synaptic membrane and therefore makes an EPSP. Prolonged exposure to glutamate leads to pathological increases in neuronal cell [Ca2+] that can kill the post-synaptic cell. This phenomenon is called excitotoxicity.

Binding of glutamate to the AMPA or kainate receptors leads to an increase in gNa and gK. These receptors are named for their artificial agonists: AMPA is α-amino-3-hydroxy-5-methylisoxazole-4-propionate. Occupancy of these receptors produces an EPSP.

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Six-membered Rings with Three or more Heteroatoms, and their Fused Carbocyclic Derivatives

P.M. Weintraub, in Comprehensive Heterocyclic Chemistry III, 2008

9.07.6.5.2 By nitrogen nucleophiles

A transamination reaction was developed to prepare 4-monosubstituted amino pyrazino[2,3-c][1,2,6]thiadiazines. Thus, reaction of 162 with a variety of amines in alcoholic solvents gave the corresponding amines 163. This method can also be used with secondary amines such as pyrrolidine (50% yield) (Scheme 12) <2000JMC4219, 2003HCA139>. When reacting an excess of methylamine with 162 (R = Et), the 4,6-bis-methylamino compound 164 (R = Et, R1 = Me) was obtained. Here, nucleophilic chlorine displacement occurred in addition to the desired displacement reaction.

The process of transferring the amine group from one amino acid to another is called

Scheme 12.

There was different reactivity shown if the C-7 position was unsubstituted. Thus, reaction of 165 with ammonia gave the addition/oxidation product 166, whereas, with methylamine, only the transamination product 167 was obtained (Scheme 13) <2003HCA139>.

The process of transferring the amine group from one amino acid to another is called

Scheme 13.

Reaction of imidates 168 with different amines using various reaction conditions resulted only in isolation of the starting material. If, instead, the sulfonates 170, prepared from λ4-thiazine 171 with methanol and p-toluenesulfonic acid anhydrides in dichloromethane at 20 °C, were reacted with amines, the desired amino compounds 169 were obtained. In the case where R1 = Bn, as compared to CF3, higher temperatures and longer reaction times were required and lower yields were obtained, confirming that electron-withdrawing substituents facilitate nucleophilic attack at C-3 (Scheme 14) <2003JOC3817> (see Section 9.07.8.5).

The process of transferring the amine group from one amino acid to another is called

Scheme 14.

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Branched-Chain Amino Acids, Part B

Corinna Prohl, ... Roland Lill, in Methods in Enzymology, 2000

Assay of Enzyme Activity of Yeast Branched-Chain Amino Acid Transaminases

The transamination of branched-chain α-keto acids (α-ketoisocaproate, α-ketoisovalerate, and α-keto-β-methylvalerate) to the corresponding amino acids (leucine, valine, and isoleucine) represents an equilibrium reaction. Thus, the reactions can be measured in both directions. The forward reactions can be determined by coupling them to the glutamate dehydrogenase reaction [see reaction (1)]. Glutamate dehydrogenase converts α-ketoglutarate to glutamate and is dependent on NAD+/NADH or NADP+/NADPH. Accordingly, the formation of branched-chain amino acids can be recorded by the decrease in NAD(P)H concentration.23

(1)Branched‐chainα‐ketoacid+glutamic⇌ acidbranched‐chainaminoacid+α‐ketoglutarateα−Ketoglutarate+NH4++NADPH⇌glutamatedehydrogenaseglutamicacid+NAD P++H2O

In the reverse reaction [reaction(2)] the formation of a hydrazone adduct with the branched-chain keto acids is measured by its absorbance at 440 nm.24 The irreversible formation of this adduct allows the quantitative determination of branched-chain α-keto acids.

(2)Branched‐chainaminoacid+α‐ketoglutarate⇌branched‐chainα‐ketoacids+glutamicacidBranched‐chainα‐ketoacid+2,4‐dinitrophenylhydrazine→α‐ketoacid2,4‐dinitrophenylhydrazone

Detailed procedures for both types of assays are provided below.

Forward Reaction. A 0.5-ml reaction mixture typically contains 0.25 ml of buffer A [200 mM Tris-HCl (pH 8.0), 100 mM NH4Cl, 0.5 mM pyridoxal phosphate, and 2 mM NaN3], 0.04 ml of 0.5 M glutamic acid, 0.01 ml of 10 mM NADH, 1 U of glutamate dehydrogenase, and 0.04 ml of sample in a quartz cuvette. The sample consists of either 30–50 μg of protein derived from yeast cell extracts or from cytosol, 10–30 μg of isolated mitochondria, or 1 μg of purified Bat1p. After reaching a stable signal of absorption at 340-nm wavelength, the transamination reaction is started by adding 0.02 ml of the desired α-keto acid (200 mM). The decrease in absorption is recorded for several minutes and expressed in units per milligram of protein. One unit is defined as the oxidation of 1 μmol of NADH per minute (extinction coefficient ε340 = 6.22 mM− 1 cm− 1). A typical result using cell extracts derived from wild-type, Δbat1, Δbat2, or Δbat1Δbat2 cells is depicted in Fig. 3A for the transamination of α-ketoisocaproate to leucine. Deletion of BAT1 results in a threefold reduction in total cellular branchedchain-amino-acid transaminase activity, whereas deletion of BAT2 only weakly affects the total transaminase activity. These data indicate that Bat1p represents the major transaminase activity for branched-chain α- keto acids in the yeast cell. In the absence of both Bat proteins, 25% residual branched-chain-amino-acid transaminase activity is detected in yeast cell extracts. At least in these in vitro experiments, proteins other than Bat1p and Bat2p can perform the conversion of branched-chain α-keto acids to leucine (Fig. 3A), isoleucine, or valine.4 Most likely, these activities are executed by other cellular transaminases with low specificity for α-keto acids with a branched aliphatic side chain.

Reverse Reaction. The reverse reaction is performed in a total volume of 1 ml containing 0.5 ml of buffer B (75 mM sodium pyrophosphate, pH 9.2), 10 μl of 6.7 mM isoleucine, leucine, or valine, 3.4 μl of 20 mM pyridoxal phosphate, and the sample to be analyzed. Typically, 300–500 μg of total cell extracts or of cytosolic fractions, 100–300 μg of isolated mitochondria, or 10 μg of purified Bat1p is used. The solution is preincubated for 5 min at 37°, and the reaction is started by adding 10 μl of 6.7 mM α-ketoglutarate. After 10 min at 37°, the transaminase reaction is terminated by the addition of 100 μl of 60% (w/v) trichloroacetic acid. The samples are centrifuged and the clarified supernatant is transferred to a 10-ml glass tube. After incubation for 5 min at 25° in a water bath, 2 ml of 2,4-dinitrophenylhydrazine [0.5% (w/v) in 2 N HCl] is added, and the incubation is continued for another 5 min. The mixture is supplemented with 5 ml of toluene and vortexed vigorously for 2 min. The bottom aqueous layer is aspirated off with a capillary pipette, and 5 ml of 0.5 N HCl is added to the organic phase. After shaking for 1 min, the insoluble hydrazone generated with α-ketoglutarate is removed by brief centrifugation. Two milliliters of the clarified toluene layer is combined with 2 ml of 10% (w/v) sodium carbonate in a fresh glass tube. After brief shaking and phase separation, 1 ml of the aqueous layer is mixed with 1 ml of 1.5 N NaOH, and the absorption is recorded at 440 nm. The levels of absorption at 440 nm of the hydrazone adducts of the three branched-chain α-keto acids are similar (extinction coefficients ε440 14 mM− 1 cm− 1). For quantitation of the enzyme activity the background absorption (mainly due to the added 2,4-dinitrophenylhydrazine) must be subtracted. To this end, the reaction is performed in parallel with buffer instead of protein sample. A typical example of this assay is presented in Fig. 3B, using leucine as a substrate and extracts derived from wild-type, Δbat1, Δbat2, or Δbat1Δbat2 yeast cells. The results are comparable to those obtained for the forward reaction.

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Amino Acid Metabolism

Antonio Blanco, Gustavo Blanco, in Medical Biochemistry, 2017

Transfer of Monocarbon Groups

In transamination reactions, amino acids can donate their amine functional group to an acceptor molecule. Some amino acids also participate in reactions in which other groups, used in the synthesis of functional important substances, are transferred. For example, the amidine group of arginine, or the amide group of glutamine and asparagine, are employed in the synthesis of various compounds.

Monocarbon groups are important molecular fragments frequently transferred in synthesis processes of more or less complex chemical structures. They may exhibit different degrees of oxidation, such as methyl (

The process of transferring the amine group from one amino acid to another is called
CH3), hydroxymethyl (
The process of transferring the amine group from one amino acid to another is called
CH2OH), formyl (
The process of transferring the amine group from one amino acid to another is called
COH), and carbon dioxide (CO2), which is also considered a monocarbon residue.

The main methyl donor is methionine; its methyl group is used in the synthesis of numerous substances such as choline, creatine, adrenaline, carnitine, and methylated RNA. This is possible only if the methionine is activated, for which it must react with ATP to form S-adenosyl methionine (SAM). The sulfur atom of methionine is attached to C5′ of adenosine. Two of the ATP phosphate groups are released as pyrophosphate and the third as an inorganic phosphate.

The process of transferring the amine group from one amino acid to another is called

SAM is the active form of methionine. The bond between methyl and sulfur is of high energy, which explains the ability of the methyl group to participate in transfer reactions. The reactions in which SAM transfers methyl groups to form different compounds are catalyzed by methyltransferases that are specific for each compound.

Homocysteine. S-adenosyl-homocysteine, a product of transmethylations, is hydrolyzed to adenosine and homocysteine. Cysteine or methionine is synthesized from this compound. There are genetic defects that alter the metabolism of homocysteine (homocysteinuria and cisteinuria).

The process of transferring the amine group from one amino acid to another is called

Increased plasma homocysteine is observed in deficiencies of vitamin B12 and folic acid. Hyperhomocysteinemia is a risk factor for atherosclerosis of coronary, cerebral, and peripheral vessels.

Another transport agent of monocarbons [methyl, methylene (

The process of transferring the amine group from one amino acid to another is called
CH2
The process of transferring the amine group from one amino acid to another is called
), methenyl (=CH
The process of transferring the amine group from one amino acid to another is called
), and formyl] is tetrahydrofolic acid (THF), a derivative of folic acid, which is a member of the vitamin B complex. Methylcobalamin, related to vitamin B12, is another essential factor in one-carbon transfer reactions. Most of these groups are donated to THF by metabolites produced by the degradation of the amino acids serine, glycine, histidine, or tryptophan and transferred for the synthesis of purine, thymine, and methionine.

Carbon dioxide (CO2) produced in the citric acid cycle or amino acid decarboxylation reaction is transferred in carboxylase catalyzed reactions. The coenzyme is the vitamin B biotin. Carboxylations require ATP and form important metabolic intermediates. The principal three carboxylases using biotin are: (1) pyruvate carboxylase, which catalyzes the first step of gluconeogenesis (also anaplerotic reaction of the citric acid cycle), (2) acetyl CoA carboxylase, involved in the first step of fatty acid synthesis, and (3) propionyl-CoA carboxylase, a key enzyme in the catabolism of valine and isoleucine.

Folic acid, vitamin B12, and biotin are further considered in Chapter 27.

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Branched-Chain Amino Acids, Part B

Hiroyuki Kagamiyama, Hideyuki Hayashi, in Methods in Enzymology, 2000

Catalytic Properties

BCAT catalyzes transamination of a variety of amino acids (Table I).4 Besides branched-chain amino acids, BCAT is active toward phenylalanine and tyrosine, both of which have bulky side chains like branched-chain amino acids. Methionine is also a fairly good substrate. While catalylzing transamination of these hydrophobic amino acids, BCAT is also active toward glutamate and its corresponding keto acid 2-oxoglutarate. Thus, like many other aminotransferases, BCAT recognizes two structurally different sets of substrates, amino/keto acids with hydrophobic side chains, and amino/keto acids with carboxylic side chains.

Before the elucidation of the three-dimensional structures of BCAT and DAAT, an interesting stereochemical study had been carried out.21 The key step in the catalytic reaction of aminotransferases is the 1,3-prototropic shift between the aldimine (Schiff base of an amino acid and PLP) and ketimine [Schiff base of a keto acid and pyridoxamine phosphate (PMP)] intermediates. For efficient removal of the α proton of the aldimine, the Cα–H bond should be perpendicular to the plane of the PLP pyridine ring. Therefore, there are two possible conformations of the PLP–substrate aldimine: in one conformation the α hydrogen resides in the si face of the aldimine, and in the other conformation in the re face. The base that assists the prototropic shift is expected to locate on one side of the aldimine. Therefore, if the aldimine takes the conformation in which the α hydrogen protrudes to the si (re) face, the si (re) face base would abstract (and exchange with solvent) both the α hydrogen of the aldimine and the pro-S (pro-R) hydrogen at C-4' of the ketimine. When apo-BCAT was reconstituted with (4' R)-[4' -3H]PMP and used as the catalyst for the transamination between 2-oxoglutarate and valine, the tritium was nearly completely released to the solvent. On the other hand, when (4' S)-[4'-3H]PMP was used for the reconstitution, essentially no radioactivity was detected in the solvent after the transamination reaction. Identical results were obtained for DAAT when it was used as a catalyst for the trasamination between D-alanine and 2-oxoglutarate. On the other hand, tritium was released only from (4' S)-[4' -3H]PMP in the catalytic reaction of AspAT (transamination between aspartate and 2-oxoglutarate), as expected from the crystallographic structure of AspAT.22 Therefore, it was concluded that the base that catalyzes the 1,3-prototropic shift of the aldimine and ketimine is located at the re face of the PLP–substrate aldimine in BCAT and DAAT. The crystallographic structures of BCAT8 and DAAT17 are consistent with this conclusion.

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URL: https://www.sciencedirect.com/science/article/pii/S0076687900242237

What is the process by which an amino group is transferred from one amino acid to a keto acid?

Transamination is the process by which amino groups are removed from amino acids and transferred to acceptor keto-acids to generate the amino acid version of the keto-acid and the keto-acid version of the original amino acid.

What is the process of removal of amine group from a molecule called?

Deamination is the removal of an amino group from a molecule. Enzymes that catalyse this reaction are called deaminases. In the human body, deamination takes place primarily in the liver, however it can also occur in the kidney.

Is transamination and deamination same?

Transamination and Deamination Transamination refers to a process of transfer of one amino group from one molecule to another, particularly from an amino acid to a keto acid. Whereas in deamination, an amino group is removed from an amino acid or other compounds.

Which group from amino acid is transferred during transamination?

Complete answer: Transamination is referred to as a chemical reaction that involves the transfer of an amino group to a keto-acid to form new amino acids. The enzyme involved in the process is called transaminase. It helps in the formation of different amino acids.