Biomaterial Database

Physical and kinetic properties of a pyridoxal reductase purified from bakers' yeast. 1988

B M Guirard, and E E Snell

Department of Microbiology, University of Texas-Austin 78712.

Pyridoxine dehydrogenase (1.1.1.65) (pyridoxal reductase), purified to homogeneity from baker's yeast, is a monomer of Mr approximately 33,000. It catalyzes the reversible oxidation of pyridoxine by NADP to yield pyridoxal and NADPH; equilibrium lies far in the direction of pyridoxine formation (Keq approximately 1.4 X 10(11) l/mol at 25 degrees C). Reduction of pyridoxal occurs most rapidly at pH 6.0-7.0; oxidation of pyridoxine is optimal at pH 8.6. NAD and NADH do not replace NADP and NADPH as substrates; pyridoxine, pyridoxal and pyridoxal 5'-phosphate are the only naturally occurring cosubstrates found. Several other aromatic aldehydes also are reduced, but substrate specificity and other properties of the enzyme distinguish it clearly from other alcohol dehydrogenases or aldehyde reductases. Between pH 6.3 and 7.1 (the intracellular pH of yeast), V/Km with pyridoxal and NADPH as substrates is greater than 600 times that observed with pyridoxine and NADPH as substrates is greater than 600 times that observed with pyridoxine and NADP as substrates. These and other considerations strongly indicate that the dehydrogenase functions in vivo to reduce pyridoxal to pyridoxine, which is the preferred substrate for pyridoxal (pyridoxine) kinase in yeast.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D002846	Chromatography, Affinity	A chromatographic technique that utilizes the ability of biological molecules, often ANTIBODIES, to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Bioaffinity,Immunochromatography,Affinity Chromatography,Bioaffinity Chromatography
D002852	Chromatography, Ion Exchange	Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.	Chromatography, Ion-Exchange,Ion-Exchange Chromatography,Chromatographies, Ion Exchange,Chromatographies, Ion-Exchange,Ion Exchange Chromatographies,Ion Exchange Chromatography,Ion-Exchange Chromatographies
D004795	Enzyme Stability	The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.	Enzyme Stabilities,Stabilities, Enzyme,Stability, Enzyme
D000429	Alcohol Oxidoreductases	A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).	Carbonyl Reductase,Ketone Reductase,Carbonyl Reductases,Ketone Reductases,Oxidoreductases, Alcohol,Reductase, Carbonyl,Reductase, Ketone,Reductases, Carbonyl,Reductases, Ketone
D012441	Saccharomyces cerevisiae	A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.	Baker's Yeast,Brewer's Yeast,Candida robusta,S. cerevisiae,Saccharomyces capensis,Saccharomyces italicus,Saccharomyces oviformis,Saccharomyces uvarum var. melibiosus,Yeast, Baker's,Yeast, Brewer's,Baker Yeast,S cerevisiae,Baker's Yeasts,Yeast, Baker
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities