TABLE 3.

Summary of residues involve in the substrate binding, catalysis and exit

Residues	Conservation/Substitution in Orthologs	Proposed Function
Phe 83	Highly/tyrosine	Position bicyclopentane ring of substrate
Leu 62	Highly/methionine	Expose Cys 65 sulfur group
Lys 59	Conserved	Facilitate substrate entry
Cys 65	Conserved	Nucleophile
Ser 45	Partial/threonine	Deprotonate Cys 65
Ser 81	Highly/alaninea	Catalysis
Ser 67	Partial/threonine	Catalysis
Trp 54	Conserved	Gating/product exit
Trp 112	Highly/tyrosine or serine	Gating/product exit
His 111	Highly/arginine	Position carboxylic tail of substrate
Tyr 107	Highly/phenyalanine	Position carboxylic tail of substrate
Leu 79	Conserved	Positioning aliphatic tail of substrate
Leu 131	Conserved	Positioning aliphatic tail of substrate
Tyr 149	Conserved	Positioning aliphatic tail of substrate
Asp 37	Highly/glutamate	Plugging of clayx
Trp 43	Conserved	Plugging of clayx
Tyr 128	Conserved	Plugging of clayx
Thr 73	Highly/alanine	Plugging of clayx
Gly 75	Conserved	Plugging of clayx
Leu 77	Highly/methionine	Plugging of clayx

^aOnly in Xenopus.