Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Comparison of X-Ray Crystal Structures of an Acyl-Enzyme Intermediate of Subtilisin Carlsberg Formed in Anhydrous Acetonitrile and in Water

Jennifer L. Schmitke, Lawrence J. Stern and Alexander M. Klibanov
Proceedings of the National Academy of Sciences of the United States of America
Vol. 95, No. 22 (Oct. 27, 1998), pp. 12918-12923
Stable URL: http://www.jstor.org/stable/46169
Page Count: 6
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Comparison of X-Ray Crystal Structures of an Acyl-Enzyme Intermediate of Subtilisin Carlsberg Formed in Anhydrous Acetonitrile and in Water
Preview not available

Abstract

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- angstrom 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.

Page Thumbnails

  • Thumbnail: Page 
12918
    12918
  • Thumbnail: Page 
12919
    12919
  • Thumbnail: Page 
12920
    12920
  • Thumbnail: Page 
12921
    12921
  • Thumbnail: Page 
12922
    12922
  • Thumbnail: Page 
12923
    12923