Explain the basis for the following statement As a coenzyme

Explain the basis for the following statement: As a coenzyme, pyridoxal phosphate (PLP) is covalently bound to enzymes with which it functions, yet during catalysis the coenzyme is not covalently bound (to the enzyme).

Solution

The pyridoxal phosphate (PLP) is the coenzyme required by the enzymes aminotransferases, which catalyzes the transfer of amino group between different keto acids to form amino acids. The PLP is the derivative of pyridoxine, which is also called vitamin B6. Pyridoxal phosphate functions as an intermediate carrier of amino groups at the active site of aminotransferases. This group undergoes reversible transformation between its aldehyde form, pyridoxal phosphate, which can accept an amino group, and its aminated form, whereas pyridoxamine phosphate can donate its amino group to an alpha-keto acid.