Analogs of Reaction Intermediates Identify a Unique Substrate Binding Site in Candida rugosa Lipase

Abstract

The structures of Candida rugosa lipase-inhibitor complexes demonstrate that the scissile fatty acyl chain is bound in a narrow, hydrophobic tunnel which is unique among lipases studied to date. Modeling of triglyceride binding suggests that the bound lipid must adopt a "tuning fork" conformation. The complexes, analogs of tetrahedral intermediates of the acylation and deacylation steps of the reaction pathway, localize the components of the oxyanion hole and define the stereochemistry of ester hydrolysis. Comparison with other lipases suggests that the positioning of the scissile fatty acyl chain and ester bond and the stereochemistry of hydrolysis are the same in all lipases which share the alpha/beta-hydrolase fold.

Homology modelling and molecular dynamics aided analysis of ligand complexes demonstrates functional properties of lipid‐transfer proteins encoded by the barley low‐temperature‐inducible gene family, blt4

“…Therefore, the second acyl chain attached to position 2 of glycerol was modelled on the surface of BLT4.9. A similar mode of phospholipid binding has been proposed for Candida rugosa lipase, which also has a hydrophobic binding tunnel (Grochulski et al, 1994). In the starting conformation, this 'external' acyl chain was positioned to interact with the hydrophobic residues around the entrance of the ligand binding tunnel of BLT4.9.…”

Computer modeling of substrate binding to lipases from Rhizomucor miehei, Humicola lanuginosa, and Candida rugosa

“…In the C. rugosa lipase, the aliphatic site is positioned in a long tunnel inside the protein. The tunnel was recently observed in X-ray crystallography studies (Grochulski et al, 1994b) and has now been shown to be involved in the binding of the scissile fatty acid chain (Grochulski et al, 1994a). The aspartic acid residues of the catalytic triads are buried in the enzymes, which may cause a large increase in their pK, values.…”

“…This lipase is structurally different from the 2 fungal lipases, although the dfl-hydrolase fold (Ollis et al, 1992) of all 3 lipases studied is conserved. Recently, it has been shown for the C. rugosa lipase that a tunnel, which is unique among lipases studied to this date, is involved in the binding of the scissile fatty acid chain (Grochulski et al, 1994a).…”

Cold active lipases – an update

“…The active site contains the catalytic triad, Ser105 (nucleophile)-His224 (basic residue)-Asp/Glu187 (acidic residue) (Ollis et al 1992). In almost all lipases, the active site is covered by a lid which opens in the presence of an interface to facilitate contact with substrate (Grochulski et al 1994;Cygler & Schrag 1997).…”