Question

Explain the basis for the following statement: As a coenzyme, pyridoxal phosphate is covalently bound to enzymes with which it functions, yet during catalysis the coenzyme is not covalently bound. Match the words in the left column to the appropriate blanks in the sentences on the right. Reset Help e-amino carboxylic acid PLP forms a covalent between the carbon of the coenzyme and an group of a lysine residue in the active site of the enzyme. This bond must be broken for the coenzyme to form a with an) substrate amide ketone amino acid Q-amino oxime carboxyl hydroxyl imino aldehyde Schiff base

Answer 1

PLP forms a covalent Schiff base between the aldehyde carbon of the coenzyme and an e-amino group of lysine residue in the active site of enzyme. This bond must be broken for the coenzyme to form a Schiff base with a(n) amino acid substrate.

Comment;- PLP (Pyroxidal phosphate) is the active form of vitamin B6. It is a coenzyme in a variety of enzymatic reaction. The aldehyde group of PLP forms a Schiff-base linkage with the e-amino group of a specific lysine group of the aminotransferase enzyme. The alpha amino group of the amino acid substrate displaces the e-amino group of the active-site lysine residue in a process known as transaldimination.