PMID: 36380Jun 25, 1979

Stereospecificity of sodium borohydride reduction of tyrosine decarboxylase from Streptococcus faecalis

The Journal of Biological Chemistry
J C VederasH W Sellers

Abstract

Sodium boro[3H]hydride reduction of tyrosine decarboxylase from Streptococcus faecalis followed by complete hydrolysis of the enzyme produces epsilon-[3H]pyridoxyllysine. Degradation of this material to [4'-3H]pyridoxamine and stereochemical analysis with apoaspartate aminotransferase shows that the re side at C-4' of the cofactor is exposed to solvent at pH 5.5 and 7.0. After binding of L-tyrosine at pH 5.5 or tyramine at pH 7.0 to the holoenzyme, sodium boro[3H]hydride reduction proceeds from the si face at C-4' of the substrate . cofactor complex. This indicates one of two conformational changes occurs upon binding of substrate; either rotation about the C-4 to C-4' bond in the cofactor or rotation about the axis through the C-5 and C-5' bond.

Related Concepts

Borohydrides
Hydrogen-Ion Concentration
Lysine Hydrochloride
Oxidation-Reduction
Plasma Protein Binding Capacity
Pyridoxal
Molecular Stereochemistry
Enterococcus faecalis
Structure-Activity Relationship
Tyrosine Decarboxylase

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