This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Cystathionine lyase requires which cofactor ? 
Select and explain. 
A. Thymine, B. Riboflavin, C. Pyridoxine, D. Niacin
C: Pyridoxine
Answer: C: Pyridoxine 
Explanation: Hydrolytic cleavage (hydrolysis) of cystathionine forms Homoserine plus cysteine.This reaction is catalyzed by the enzyme cystathionine lyase (cystathionase), which requires cofactor pyridoxal phosphate (active form of pyridoxin).