Identify the group in pyridoxal phosphate (PLP) that covalently binds enzyme and
ID: 65402 • Letter: I
Question
Identify the group in pyridoxal phosphate (PLP) that covalently binds enzyme and substrate. Aminotransferases (transaminases) must deaminate one amino acid and add an amino group to another amino acid during transamination. How do the two processes differ? The second part of the reaction (adding an amino group) is the reverse of the first (deamination). The second part of the reaction takes place at a separate amino add residue in the active site. The first reaction involves the formation of a Schiff base, whereas the second does not. The coenzyme PLP must be activated by an external amino group before it can catalyze the removal of the amino group from the first amino acid.Explanation / Answer
a) The –OH group of the pyridoxal phosphate (PLP) covalently binds enzyme and substrate
Hence, the correct option is (B)
(b) Transamination is catalyzed by transaminases that require participation of pyridoxal phosphate and forms a Schiff base.
In this reaction first the amino acid forms the sciff's base and the the same amino acid forms the sciff's base with second keto acid in the second reaction which an opposite reaction to that of the first.
Hence, the correct option is "The second part of the reaction (adding an amino group) is the reverse of the first (deamination).