Answer to Question #86072 in Biochemistry for Ankur Solanki

Question

Give the role of following vitamins in biochemical reactions.Explain with the help of an example.
(i)Thiamine
(ii) Pyridoxine
(iii)Riboflavin

Answer 1

1). The derivative of thiamine, thiamine pyrophosphate (TPP) is a coenzyme for several enzymes that catalyze the transfer of two-carbon units and in particular the dehydrogenation of alpha-keto acids. For example TPP is a coenzyme of pyruvate dehydrogenase and responsible for the transfer of pyruvate to acetyl-CoA by attacking the electrophilic ketone of pyruvate.

2). The derivative of pyridoxine - pyridoxal phosphate acts as coenzyme in such biochemical reaction as decarboxylation, for example conversion of 5-hydroxytryptophan (5-HTP) to serotonin.

3). Riboflavin forms two coenzymes - flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). FMN is a cofactor of oxidoreductases in electron transport chain. FMN is a strong oxidizing agent because it can take part in both one- and two-electron transfers. FAD is a coenzyme of various aerobic dehydrogenases (for example, α-ketoglutarate dehydrogenase and a component of the pyruvate dehydrogenase complex).FAD acts as an acceptor of H⁻ and e⁻ in its fully oxidized form, an acceptor or donor in the FADH form, and a donor in the reduced FADH₂