1be6

From Proteopedia

Revision as of 13:48, 5 November 2007

TRANS-CINNAMOYL-SUBTILISIN IN ANHYDROUS ACETONITRILE

Overview

The x-ray crystal structures of trans-cinnamoyl-subtilisin, an acyl-enzyme, covalent intermediate of the serine protease subtilisin Carlsberg, have, been determined to 2.2-A resolution in anhydrous acetonitrile and in, water. The cinnamoyl-subtilisin structures are virtually identical in the, two solvents. In addition, their enzyme portions are nearly, indistinguishable from previously determined structures of the free enzyme, in acetonitrile and in water; thus, acylation in either aqueous or, nonaqueous solvent causes no appreciable conformational changes. However, the locations of bound solvent molecules in the active site of the acyl-, and free enzyme forms in acetonitrile and in water are distinct. Such, differences in the active site solvation may contribute to the observed, variations in enzymatic activities. On prolonged exposure to organic, solvent or removal of interstitial solvent from the crystal lattice, the, channels within enzyme crystals are shown to collapse, leading to a drop, in the number of active sites accessible to the substrate. The mechanistic, and preparative implications of our findings for enzymatic catalysis in, organic solvents are discussed.

About this Structure

1BE6 is a Single protein structure of sequence from Bacillus licheniformis with CA, TCA and CCN as ligands. Active as Subtilisin, with EC number 3.4.21.62 Structure known Active Site: ACT. Full crystallographic information is available from OCA.

Reference

Comparison of x-ray crystal structures of an acyl-enzyme intermediate of subtilisin Carlsberg formed in anhydrous acetonitrile and in water., Schmitke JL, Stern LJ, Klibanov AM, Proc Natl Acad Sci U S A. 1998 Oct 27;95(22):12918-23. PMID:9789015

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