β Scribed by K. K. Kannan; M. Ramanadham
No coin nor oath required. For personal study only.
The three dimensional structure of human carbonic anhydraseβB has been model fitted to electron density maps in an interactive graphics display and improved by real space refinement and restrained leastβsquares refinement. The crystallographic R factor for the 5 to 3 Γ data dropped from 41.5% to 36.5% after four cycles of leastβsquares 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.
π SIMILAR VOLUMES
A new model for catalysis of human carbonic anhydrase II is suggested. The model is based on the X-ray structure of the hydrogen bond network in the catalytic site. The outer part of the network is proposed to adjust the pK a of the catalytic site to the experimentally observed value of about 7. The