Structure, refinement, and function of human carbonic anhydrase-B

Abstract

The three dimensional structure of human carbonic anhydrase-B has been model fitted to electron density maps in an interactive graphics display and improved by real space refinement and restrained least-squares refinement. The crystallographic R factor for the 5 to 3 Å data dropped from 41.5% to 36.5% after four cycles of least-squares refinement. The important residues involved in the function of the enzyme showed improved positional parameters after the refinement. Thus GLU106 and THR199 oxygen atoms are within hydrogen bond distance of each other after the refinement. Whereas they were very close to each other before the refinement. The procedures involved in the refinement and the implication of the structure to the mechanism of action of the enzyme are brought out.