Active site geometry of porcine pancreatic lipase: an interesting switchover from Jonesʹ to Seebachʹs model

Porcine pancreatic lipase (PPL)-catalyzed hydrolysis of cis 3-acetoxyethyl-1,4-diphenyl and cis 3-acetoxyethyl-1-phenyl-4-(2-furyl) β-lactams 1a and 1b proceeded with opposite stereoselectivity while the corresponding thienyl β-lactam 1c showed no selectivity at all. An explanation based upon the dominance of hydrophobic and polar pockets in governing the stereoselectivity has been proposed.