J. Birktoft, D. Blow
Jul 21, 1972
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2
Influential Citations
580
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Journal
Journal of molecular biology
Abstract
Abstract Refined atomic co-ordinates for tosyl-α-chymotrypsin have been obtained by computational refinement of co-ordinates derived from a carefully built atomic model. The two independent views of the molecule obtained from crystallographic analysis are almost identical. The structure of the enzyme is described in terms of conformational angles, hydrogen-bonding networks and the environment of different types of amino-acid side chain. The polypeptide chain is folded into two hydrogen-bonded cylinders, each enclosing a hydrophobic core. Many solvent molecules can be identified, including 13 buried between the hydrogen-bonded cylinders, inside the molecule. The structural differences observed in the native form of the enzyme are considered in relation to hydrogen bonds at the active centre. Co-ordinates are given for the two amino acids (His57 and Ser195) which are measurably different in the native form. The interactions between molecules related by local 2-fold axes are compared with the association properties observed in solution.