Can I read About the pK~a~ of the active‐site histidine in flavocytochrome b~2~ (yeast L‐lactate dehydrogenase) on EtoBox?

About the pK~a~ of the active‐site histidine in flavocytochrome b~2~ (yeast L‐lactate dehydrogenase) by K. Sudhindra Rao; Florence Lederer is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

What is About the pK~a~ of the active‐site histidine in flavocytochrome b~2~ (yeast L‐lactate dehydrogenase) about?

## Abstract Flavocytochrome __b~2~__ or L‐lactate dehydrogenase from yeasts catalyzes the oxidation of L‐lactate at the expense of monoelectronic acceptors such as cytochrome __c__, its physiological partner. When incubated in the presence of both L‐lactate and a keto acid, the enzyme catalyzes a transhydrogenation reaction wherein only the flavin is involved. During this reaction, the substrate α‐hydrogen is transferred not only to the solvent but also in part to the keto acid, which acts as reverse substrate. Thus, when bound to the reduced enzyme, this hydrogen is sticky. In the context of a carbanion mechanism, it resides on Nε of His373, the active site base. We have shown before that a correlation between the amount of intermolecular hydrogen transfer from [2‐^3^H] lactate and the keto acid reverse substrate concentration enables the determination of the first‐order rate constant, __k^H^~e~__ for exchange of the substrate‐derived protein‐bound hydrogen with bulk solvent (Urban P, Lederer F, 1985, __J Biol Chem__ 260:11115‐11122). In this work, we show that the exchange with the solvent appears to be independent of the phosphate buffer concentration in the range from 40 to 500

Who reads About the pK~a~ of the active‐site histidine in flavocytochrome b~2~ (yeast L‐lactate dehydrogenase)?

Author

K. Sudhindra Rao; Florence Lederer

Publisher

Cold Spring Harbor Laboratory Press; Wiley (John Wiley & Sons); Wiley-Blackwell; Wiley (ISSN 0961-8368)

Published

1998

Language

EN

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)