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.

Active Site of α -chymotrypsin Activation by Association-Desolvation

Saul G. Cohen, Vishnu M. Vaidya and Richard M. Schultz
Proceedings of the National Academy of Sciences of the United States of America
Vol. 66, No. 2 (Jun. 15, 1970), pp. 249-256
Stable URL: http://www.jstor.org/stable/60046
Page Count: 8
  • 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.
Active Site of α -chymotrypsin Activation by Association-Desolvation
Preview not available

Abstract

High reactivity toward α -chymotrypsin is observed for derivatives of β -arylpropionic acids of varied structure-L-α -acylamido compounds, D-cyclized compounds, and, now, L-glycolamide esters. Compensating enthalpy and entropy effects are observed which appear to be caused by changes in water of solvation. High reactivity with varied structure, and physical evidence, appear to rule out induced fit and distortion as important for this enzyme. The high reactivity results from precise fit of the hydrolyzing group at the critical serine-imidazole junction, resulting from binding of the aryl group and restriction of rotation. Part of the energy of binding is used to desolvate the reactant groups of substrate and enzyme, decreasing activation energies by several kilocalories and raising reactivity by 103 or more. Solvation by water stabilizes many compounds, allowing them to be present in solution in biological systems. Their reactions may occur as their reactivity is increased when they are desolvated and brought from solution into association with reactive groups in enzymes, membranes, and structured particles.

Page Thumbnails

  • Thumbnail: Page 
249
    249
  • Thumbnail: Page 
250
    250
  • Thumbnail: Page 
251
    251
  • Thumbnail: Page 
252
    252
  • Thumbnail: Page 
253
    253
  • Thumbnail: Page 
254
    254
  • Thumbnail: Page 
255
    255
  • Thumbnail: Page 
256
    256