The Bacterial Oxidation of Vitamin B6

Sparrow, Lindsay G.; Ho, Peter P.K.; Sundaram, T. K.; Zach, D.; Nyns, E. J.; Snell, Esmond E.

doi:10.1016/s0021-9258(18)83441-x

Cited by 68 publications

(33 citation statements)

References 18 publications

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“…Reagents. MHPC and 5HN were synthesized as previously described in ref . NAD + , NADH, glucose-6-phosphate, and glucose-6-phosphate dehydrogenase were from Sigma.…”

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

“…2-Methyl-3-hydroxypyridine-5-carboxylic acid (MHPC) 1 oxygenase (MHPCO) (EC 1.14.12.4) is an FAD-containing enzyme involved in the degradation of vitamin B 6 (pyridoxine) by the soil bacterium, Pseudomonas sp. MA-1 (P-MA1) (1). Degradation of vitamin B 6 proceeds via an oxidative pathway that is induced when these bacteria are grown on pyridoxine or pyridoxamine as their sole source of carbon and nitrogen (2)(3).…”

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confidence: 99%

“…The pathway consists of a series of oxidative, hydrolytic, and decarboxylation reactions that convert pyridoxine to metabolites readily assimilated for growth. MHPCO catalyzes an oxygenation reaction and a ring cleavage of its substrate, MHPC, to yield R-(Nacetylaminomethylene)succinic acid (AAMS), as shown in Scheme 1 (1).…”

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confidence: 99%

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Reaction of 2-Methyl-3-hydroxypyridine-5-carboxylic acid (MHPC) Oxygenase withN-Methyl-5-hydroxynicotinic acid: Studies on the Mode of Binding, and Protonation Status of the Substrate

et al. 1997

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Titrations of 2-methyl-3-hydroxypyridine-5-carboxylic acid (MHPC) oxygenase with the substrate MHPC identified the MHPC species bound to the enzyme as the tripolar ionic species. This result was supported by studies of the binding to the enzyme of N-methyl-5-hydroxynicotinic acid (NMHN), an MHPC analog existing only in the tripolar ionic form. The Kd is 55 microM compared to a Kd of 9.2 microM for MHPC and 5.2 microM for 5-hydroxynicotinic acid. Kinetics studies of the binding of NMHN to MHPC oxygenase show that its binding, like that for MHPC and for 5HN, is also a two-step process. Since NMHN never exists as an anionic form, neither of the observed steps is due to the binding of an anionic species as an intermediate step. Investigations of the reduction and oxygenation half reactions demonstrate that the mechanism of catalysis with NMHN is basically the same as with MHPC or with 5-hydroxynicotinic acid. Product analysis from reactions using NMHN, a compound that possesses positive charge on the nitrogen atom, indicates that the product of NMHN is an aliphatic compound, similar to the products derived from MHPC and from another substrate analog, 5-hydroxynicotinic acid. These results indicate that the nitrogen atom of the substrate is invariably protonated during the catalytic reaction.

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“…Reagents. MHPC and 5HN were synthesized as previously described in ref . NAD + , NADH, glucose-6-phosphate, and glucose-6-phosphate dehydrogenase were from Sigma.…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Reaction of 2-Methyl-3-hydroxypyridine-5-carboxylic acid (MHPC) Oxygenase withN-Methyl-5-hydroxynicotinic acid: Studies on the Mode of Binding, and Protonation Status of the Substrate

et al. 1997

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“…These results clearly indicate that the crystal of the complex is that of a kinetically significant intermediate of the enzymic reaction, and that the activator site and the substrate-binding site are one and the same; in other words, an activator site or an allosteric site need not be assumed. It is very important to point out here that the activation of the catalyzed reaction caused by the aromatic substrate is seen not only with phydroxybenzoate hydroxylase but also with at least two other FAD-containing oxygenases: salicylate hydroxylase (Katagiri et al, 1965) and 2-methyl-3-hydroxypyridine-5carboxylate oxygenase (Sparrow et al, 1969). This suggests a possibility that a general activation mechanism may be shared with all these enzymes in common.…”

Section: Resultsmentioning

confidence: 75%