4WBC

2.13 A STRUCTURE OF A KUNITZ-TYPE WINGED BEAN CHYMOTRYPSIN INHIBITOR PROTEIN

Replaces:  3WBC

Summary for 4WBC

• Entry DOI: 10.2210/pdb4wbc/pdb
• Descriptor: PROTEIN (CHYMOTRYPSIN INHIBITOR), SULFATE ION (3 entities in total)
• Functional Keywords: serine protease inhibitor
• Biological source: Psophocarpus tetragonolobus (winged bean)
• Total number of polymer chains: 1
• Total formula weight: 20747.16

Authors

Ravichandran, S.,Sen, U.,Chakrabarti, C.,Dattagupta, J.K. (deposition date: 1999-03-04, release date: 1999-03-12, Last modification date: 2024-11-06)

Primary citation

Ravichandran, S.,Sen, U.,Chakrabarti, C.,Dattagupta, J.K.
Cryocrystallography of a Kunitz-type serine protease inhibitor: the 90 K structure of winged bean chymotrypsin inhibitor (WCI) at 2.13 A resolution.
Acta Crystallogr.,Sect.D, 55:1814-1821, 1999

PubMed Abstract: 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.

PubMed: 10531477
DOI: 10.1107/S0907444999009877

Experimental method

X-RAY DIFFRACTION (2.138 Å)