Fig. 2.

Reactions, mechanisms, and structural and chemical classifications of three enzymes that share one catalytic step, PI-PLC, GDPD, and RNase-A. A The balanced chemical reactions each enzyme catalyses. B The catalytic rules that are observed in the three mechanisms. C Schematic representation of the mechanisms of each enzyme. The shapes of the enzymes represent their catalytic folds, i.e. — RNase-A has a different fold. A metal ion in GDPD is represented by a green circle. D Scheme showing the differences and similarities between pairs of the three enzymes