The first structure at 1.8 A resolution of an active autolysate form of porcine alpha-trysoin.
The first crystal structure of an active autolysate form of porcine alpha-trypsin (APT), a two-chain molecule obtained from the limited autolysis of porcine beta-trypsin at position Lys145-Ser146, has been determined. APT crystallizes in space group P2(1)2(1)2(1) with one protein molecule in the asymmetric unit. The structure was solved by molecular replacement followed by refinement using X-PLOR to an R factor of 0.200 and an R(free) of 0.285 for 8.0-1.8 A data with r.m.s deviations from ideal values of 0.01 A and 1.7 degrees for bond lengths and bond angles, respectively. Comparison with inactive autolysate porcine epsilon-trypsin (EPT) and porcine beta-trypsin in complex with bittergourd trypsin inhibitor (MCT) revealed a small but systematic directional chain shift around the active-site residues from APT to EPT to MCT.
Department of Crystallography and Biophysics, University of Madras, India.
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Johnson
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Krishnaswamy
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Sundaram
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Pattabhi