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
The following is an enzyme required for glycolysis: 
Select and explain. 
A. Pyruvate kinase, B. Pyruvate carboxylase, C. Glucose-6-phosphatase, D. Glycerokinase
A: Pyruvate kinase
Answer: A: Pyruvate kinase 
Explanation: Phosphoenol pyruvate (PEP) is dephosphorylated to pyruvate, by pyruvate kinase. First PEP is made into a transient intermediary of enol pyruvate; which is spontaneously isomerized into keto pyruvate, the stable form of pyruvate.
Reference: Vasudevan 7th  ed, pg 108