Answer to Question #1177 in Biochemistry for charlie

Question

Aldehyde dehydrogenase (ALDH) catalyses the conversion of aldehyde to acetate. Please explain how the change of the cycteine to tyrosin at position 19 of ALDH causes the loss of the function of ALDH.

Answer 1

The point mutation in residue 19 (Cys to Tyr) has dramatic effect on physico-chemical properties of ALDH, its 3 dimensional structure and thus function. Cys usually facilitates the formation of protein tertiary structure pairing with each other.
Substitution to Tyr disrupts this pairing and makes conformational changes probably in the active site of the enzyme. It also results in decreased solubility of the protein, which prevents the enzyme form normally bind to and convert its substrate.