Diffraction data for alpha-chymotrypsin crystals at -10 degrees C were measured at 1.68 A resolution and refined by restrained structure-factor least-squares refinement. The two independent chymotrypsin molecules in the crystallographic asymmetric unit were refined independently ...
Diffraction data for alpha-chymotrypsin crystals at -10 degrees C were measured at 1.68 A resolution and refined by restrained structure-factor least-squares refinement. The two independent chymotrypsin molecules in the crystallographic asymmetric unit were refined independently. The overall structure of alpha-chymotrypsin is little changed from published co-ordinates. The root-mean-square shift of C alpha co-ordinates is 0.42 A, co-ordinates for the two molecules showing a root-mean-square difference of 0.19 A. Certain regions with high disorder (residues 9 to 14, 73 to 79) remain difficult to interpret and several side-chains are disordered. Some water molecule positions have been changed. The absence of the tosyl group has made a significant difference to the refined structure at the active site. This now agrees closely with other enzymes of the trypsin family that have been refined at high resolution. There is a strong hydrogen bond between N epsilon 2 (His57) and O gamma (Ser195) in the free enzyme, in line with the published description of the charge relay system.
Related Citations:
Structure and Mechanism of Chymotrypsin Blow, D.M. (1976) Acc Chem Res 9: 145
The Active Centers of Serine Proteinases Hartley, B.S. (1974) Ann N Y Acad Sci 227: 438
Comparison of the Crystal Structures of Chymotrypsinogen-A and Alpha-Chymotrypsin Wright, H.T. (1973) J Mol Biol 79: 1
Structure of Crystalline Alpha-Chymotrypsin. V. The Atomic Structure of Tosyl-Alpha-Chymotrypsin at 2 Angstroms Resolution Birktoft, J.J., Blow, D.M. (1972) J Mol Biol 68: 187
Alpha-Chymotrypsin,What Can We Learn About Catalysis from X-Ray Diffraction (Query). Henderson, R., Wright, C.S., Hess, G.P., Blow, D.M. (1972) Cold Spring Harb Symp Quant Biol 36: 63
Chymotrypsin-Chemical Properties and Catalysis Hess, G.P. (1971) The Enzymes,third Edition 3: 213
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Three-Dimensional Structure of Tosyl-Alpha-Chymotrypsin Matthews, B.W., Sigler, P.B., Henderson, R., Blow, D.M. (1967) Nature 214: 652
Organizational Affiliation:
Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294; paulg@uab.edu.
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