Kurland, I J, M R El-Maghrabi, and S J Pilkis. 1993. “Lack of Evidence for a Role of Cys-138 As a Base Catalyst in the Skeletal Muscle 6-Phosphofructo-2-Kinase Reaction.”. Biochemical and Biophysical Research Communications 195 (1): 229-36.
Abstract
The role of Cys-138 in the catalysis of the skeletal muscle 6-phosphofructo-2-kinase reaction was investigated by mutating this residue to serine, glutamine and alanine, expressing the mutants in E. coli with a T7 RNA polymerase-based expression system, and analyzing their kinetic properties. The Cys138Ala mutant had greatly diminished activity, while the Cys138Ser and Cys138Gln mutants had maximal velocities 2-3 fold higher than the wild-type enzyme. It was concluded that Cys-138 does not act as a base catalyst in the kinase reaction, but that it plays a significant structural role in the enzyme's active site.