Enolase catalyzed beta,gamma-alpha,beta isomerization of 2-phospho-3-butenoic acid to (Z)-phosphoenol-alpha-ketobutyrate.

2-Phospho-3-butenoic acid was synthesized and found to be a substrate for both yeast and rabbit muscle enolase (EC 4.2.1.11). Enolase catalyzes the isomerization of 2-phospho-3-butenoic acid to (Z)-phosphoenol-alpha-ketobutyrate, a beta,gamma-alpha,beta isomerization. Nuclear magnetic resonance studies on the product indicate only one isomer is formed. This reaction provides indirect evidence in further support of a carbanion intermediate for the enolase reaction. 2-Phospho-3-butenoic acid is also a good competitive inhibitor of both yeast and rabbit muscle pyruvate kinase (EC 2.7.1.40).