Inactivation of serine transhydroxymethylase and threonine aldolase activities

Akhtar, Muhammad; El-Obeid, Humeida A.

doi:10.1016/0005-2744(72)90180-5

Cited by 18 publications

(14 citation statements)

References 8 publications

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“…Extensive investigations will be conducted on whether the enzyme also catalyzes the reverse synthesis of phydroxy-a-amino acids other than threonine [35]. The enzyme failed to act on D-Serine and L-serine even in the presence of L-tetrahydrofolic acid, a coenzyme of serine hydroxymethyltransferase, unlike L-threonine aldolase that is able to cleave L-serine into formaldehyde and glycine [6,7,[36][37][38]. This indicates that it appears to be different from the hypothetical Dserine hydroxymethyltransferase that has not yet been found.…”

Section: Molecular Massmentioning

confidence: 99%

Isolation and Characterization of D‐Threonine Aldolase, A Pyridoxal‐5′‐Phosphate‐Dependentenzyme from Arthrobacter sp. DK‐38

Kataoka

Ikemi

Morikawa

et al. 1997

European Journal of Biochemistry

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-EJB 97 0741/4 D-Threonine aldolase is an enzyme that catalyzes the cleavage of D-threonine into glycine and acetaldehyde. Its activity was found in several genera of bacteria such as Arthrobacter, Alcaligenes, Xanthomonus, and Pseudonzonas, but not in yeasts or fungi. The enzyme was purified to homogeneity from one strain, Arthrobacter sp. DK-38. The enzyme appeared to consist of a single polypeptide chain with an apparent molecular mass of 51 kDa. This enzyme, as we11 as L-threonine aldolase, requires pyridoxal 5'-phosphate (pyridoxal-P) as a coenzyme. Unlike other pyridoxal-P enzymes, D-threonine aldolase also requires a divalent cation such as Co2+, Ni2+, Mnz+, or Mgz+ for its catalytic activity. The enzyme completely lost its activity in the absence of either pyridoxal-P or a divalent cation. A divalent cation was also essential for the thermal stability of the enzyme. The metal-free enzyme tends to become thermally unstable, resulting in the irreversible loss of its catalytic activity. The enzyme is strictly D-specific for the a-position, whereas it cannot distinguish between threo and erythro forms at the /$position. Thus, D-threonine and D-allothreonine act as substrates of the enzyme, but their kinetic parameters are different : the K,,, and V,,;,, values are 3.81 mM and 38.8 pmol . min-l . mg-' toward D-threonine, and 14.0 mM and 102 pmol . min-' . mg-l toward D-allothreonine, respectively. The aldolase reaction is reversible, and the enzyme is therefore able to produce nearly equimolar amounts of D-threonine and D-allothreonine through C-C bond formation between glycine and acetaldehyde. The enzyme also acts, in the same manner, on several other D-P-hydroxy-a-amino acids, including D-P-phenylserine, D-p-hydroxy-a-aminovaleric acid, ~-p-3,4-dihydroxyphenylserine, and D-~-3,4-methylenedioxyphenylserine.Keywords: D-threonine aldolase; threonine; Arthrohacter; pyridoxal %phosphate; divalent cation.Several enzymes are involved in L-threonine metabolism. Some are enzymes concerned in the biosynthesis of L-threonine from aspartic acid via homoserine 11, 21. Others are enzymes responsible for L-threonine degradation, such as L-threonine deaminase, which converts L-threonine into n-ketobutyrate, an intermediate in ~-isoleucine biosynthesis [3-51.L-Threonine aldolase, one of the L-threonine-degrading enzymes, cleaves L-threonine into glycine and acetaldehyde [6-91. Its enzyme activity has been found in several microorganisms, in such genera as Pseudomonas [lo], Clostridium 18,11, 121, Bacillus [13], and Candida [14, 151, as well as in mammalian organs [16, 171. L-Threonine aldolase has been extensively investigated because of its possible role in amino acid metabolism [lo, 111. Studies on the mechanism underlying its catalytic action revealed that L-threonine aldolase belongs to a group of enzymes that require pyridoxal 5'-phosphate (pyridoxal-P) as a coenzyme L-Threonine aldolase can produce the L-forms of threonine stereoisomers via C-C bond formation between glycine and acetaldehyde, though it is highly sele...

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Section: Molecular Massmentioning

confidence: 99%

Isolation and Characterization of D‐Threonine Aldolase, A Pyridoxal‐5′‐Phosphate‐Dependentenzyme from Arthrobacter sp. DK‐38

Kataoka

Ikemi

Morikawa

et al. 1997

European Journal of Biochemistry

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“…In a fairly recent paper [35], Yeung asserts that the method of assay can confuse the detection of putative aldolase activity with threonine dehydratase activity and that there is no threonine aldolase in cytosolic liver extracts from normal or starved rats. Such mixed reports are augmented by the work of Schirch and Gross [13], which has been confirmed by others [36], who showed that homogeneous preparations of rabbit liver serine transhydroxymethylase also have threonine/allothreonine aldolase activity. Along similar lines, Palekar et al [37] established the identity of cytoplasmic serine transhydroxymethylase and allothreonine aldolase with rat liver aminomalonate decarboxylase; the final homogeneous enzyme preparation exhibited no activity towards Lthreonine.…”

Section: Discussionmentioning

confidence: 75%

Identity and some properties of the l-threonine aldolase activity manifested by pure 2-amino-3-ketobutyrate ligase of Escherichia coli

Marcus

Dekker

1993

Biochimica et Biophysica Acta (BBA) - Protein Structure and Mol

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2-Amino-3-ketobutyrate ligase catalyzes the reversible, pyridoxal 5'-phosphate-dependent condensation of glycine with acetyl CoA forming the unstable intermediate, 2-amino-3-ketobutyrate. Several independent lines of evidence indicate that the pure protein obtained in the purification of this ligase from Escherichia coli also has L-threonine aldolase activity. The evidence includes: (a), a constant ratio of specific activities (aldolase/ligase) at all stages of purifying 2-amino-3-ketobutyrate ligase to homogeneity; (b), the same rate of loss of aldolase and ligase activities during controlled heat inactivation of the pure protein at 60 degrees C in the absence, as well as in the presence of acetyl CoA, a protective substrate; (c), ratios of the two enzymatic activities that are not significantly different during slow inactivation by iodoacetamide, with and without L-threonine added; (d), coincident rates of loss and essentially identical rates of recovery of aldolase activity and ligase activity during resolution of the holoenzyme with hydroxylamine followed by reconstitution with pyridoxal 5'-phosphate. No aldolase activity is observed with D-threonine as substrate and L-allothreonine is about 25% as effective as L-threonine. Whereas ligase activity has a sharp pH optimum at 7.5, the aldolase activity of this pure protein is maximal at pH 9.0. Comparative apparent Km values for glycine (ligase) and L-threonine (aldolase) are 10 mM and 0.9 mM, respectively, whereas corresponding respective Vmax values were found to be 2.5 mumol of CoA released/min per mg vs. 0.014 mumol of acetaldehyde formed (NADH oxidized)/min per mg.

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“…Aldol cleavage activities toward l ‐ allo ‐threonine has been detected in mammals [6, 7], plants [10], and microorganisms [1, 3, 11], but most of such activities have been found to be due to l ‐threonine aldolase or serine hydroxymethyl‐transferase (SHMT) [10–12]. In aerobic bacteria, aldolase activities for both threonine isomers were separated from SHMT activity by chromatography and were shown to be due to a single enzyme l ‐threonine aldolase (EC 4.1.2.5), which utilizes both l ‐threonine and l ‐ allo ‐threonine as substrates [1, 3].…”

Section: Discussionmentioning

confidence: 99%

“…l ‐Threonine aldolase ( l ‐threonine acetaldehyde‐lyase, EC 4.1.2.5) cleaves l ‐threonine into glycine and acetaldehyde and is thought to play a role in the degradation of l ‐threonine. The activity of the enzyme has been detected in several microorganisms, such as Pseudomonas [1], Clostridium [2], Bacillus [3] and Candida [4, 5], and in mammalian organs [6, 7]. l ‐Threonine aldolase cleaves not only l ‐threonine but also l ‐ allo ‐threonine [1, 3, 7].…”

Section: Introductionmentioning

confidence: 99%

Purification and characterization of l-allo-threonine aldolase from Aeromonas jandaei DK-39

Kataoka

Wada

Nishi

et al. 2006

FEMS Microbiology Letters

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L-allo-Threonine aldolase (L-allo-threonine acetaldehyde-lyase), which exhibited specificity for L-allo-threonine but not for L-threonine, was purified from a cell-free extract of Aeromonas jandaei DK-39. The purified enzyme catalyzed the aldol cleavage reaction of L-allo-threonine (K(m) = 1.45 mM, Vmax = 45.2 mumol min-1 mg-1). The activity of the enzyme was inhibited by carbonyl reagents, which suggests that pyridoxal-5'-phosphate participates in the enzymatic reaction. The enzyme does not act on either L-serine or L-threonine, and thus it can be distinguished from serine hydroxy-methyltransferase (L-serine:tetrahydrofolate 5,10-hydroxy-methyltransferase, EC 2.1.2.1) or L-threonine aldolase (EC 4.1.2.5).

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Inactivation of serine transhydroxymethylase and threonine aldolase activities

Cited by 18 publications

References 8 publications

Isolation and Characterization of D‐Threonine Aldolase, A Pyridoxal‐5′‐Phosphate‐Dependentenzyme from Arthrobacter sp. DK‐38

Isolation and Characterization of D‐Threonine Aldolase, A Pyridoxal‐5′‐Phosphate‐Dependentenzyme from Arthrobacter sp. DK‐38

Identity and some properties of the l-threonine aldolase activity manifested by pure 2-amino-3-ketobutyrate ligase of Escherichia coli

Purification and characterization of l-allo-threonine aldolase from Aeromonas jandaei DK-39

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