Vitamin B6 nutritional status and cellular availability of pyridoxal 5'-phosphate govern the function of the transsulfuration pathway's canonical reactions and hydrogen sulfide production via side reactions.

ABSTRACT: The transsulfuration pathway (TS) acts in sulfur amino acid metabolism by contributing to the regulation of cellular homocysteine, cysteine production, and the generation of H2S for signaling functions. Regulation of TS pathway kinetics involves stimulation of cystathionine β-synthase (CBS) by S-adenosylmethionine (SAM) and oxidants such as H2O2, and by Michaelis-Menten principles whereby substrate concentrations affect reaction rates. Although pyridoxal phosphate (PLP) serves as coenzyme for both CBS and cystathionine γ-lyase (CSE), CSE exhibits much greater loss of activity than CBS during PLP insufficiency. Thus, cellular and plasma cystathionine concentrations increase in vitamin B6 deficiency mainly due to the bottleneck caused by reduced CSE activity. Because of the increase in cysta

SUBMITTER: Gregory JF 

PROVIDER: S-EPMC4899128 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature