The crystal structure of a Kunitz-type double-headed alpha--chymotrypsin inhibitor from winged bean seeds has been refined at 2.13 A resolution using data collected from cryo-cooled (90 K) crystals which belong to the hexagonal space group P6(1)22 with unit-cell parameters a = b = 60 ...
The crystal structure of a Kunitz-type double-headed alpha--chymotrypsin inhibitor from winged bean seeds has been refined at 2.13 A resolution using data collected from cryo-cooled (90 K) crystals which belong to the hexagonal space group P6(1)22 with unit-cell parameters a = b = 60.84, c = 207.91 A. The volume of the unit cell is reduced by 5.3% on cooling. The refinement converged to an R value of 20.0% (R(free) = 25.8%) for 11100 unique reflections and the model shows good stereochemistry, with r.m.s. deviations from ideal values for bond lengths and bond angles of 0.011 A and 1.4 degrees, respectively. The structural architecture of the protein consists of 12 antiparallel beta-strands joined in the form of a characteristic beta-trefoil fold, with the two reactive-site regions, Asn38-Leu43 and Gln63-Phe68, situated on two external loops. Although the overall protein fold is the same as that of the room-temperature model, some conformational changes are observed in the loop regions and in the side chains of a few surface residues. A total of 176 ordered water molecules and five sulfate ions are included in the model.
Related Citations:
Refined crystal structure (2.3 A) of a double-headed winged bean alpha-chymotrypsin inhibitor and location of its second reactive site. Dattagupta, J.K., Podder, A., Chakrabarti, C., Sen, U., Mukhopadhyay, D., Dutta, S.K., Singh, M. (1999) Proteins 35: 321
Structure of a Kunitz-type chymotrypsin from winged bean seeds at 2.95 A resolution. Dattagupta, J.K., Podder, A., Chakrabarti, C., Sen, U., Dutta, S.K., Singh, M. (1996) Acta Crystallogr D Biol Crystallogr 52: 521
Crystallization and preliminary X-ray studies of psophocarpin B1, a chymotrypsin inhibitor from winged bean seeds. Dattagupta, J.K., Chakrabarti, C., Podder, A., Dutta, S.K., Singh, M. (1990) J Mol Biol 216: 229
Organizational Affiliation:
Crystallography Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Calcutta 700 064, India.
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