2BTC

BOVINE TRYPSIN IN COMPLEX WITH SQUASH SEED INHIBITOR (CUCURBITA PEPO TRYPSIN INHIBITOR II)

Summary for 2BTC

• Entry DOI: 10.2210/pdb2btc/pdb
• Descriptor: PROTEIN (TRYPSIN), PROTEIN (TRYPSIN INHIBITOR), CALCIUM ION, ... (4 entities in total)
• Functional Keywords: serine proteinase, trypsin inhibitor, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Bos taurus (cattle); More
• Cellular location: Secreted, extracellular space: P00760; Secreted: P10293
• Total number of polymer chains: 2
• Total formula weight: 26630.30

Authors

Helland, R.,Berglund, G.I.,Otlewski, J.,Apostoluk, W.,Andersen, O.A.,Willassen, N.P.,Smalas, A.O. (deposition date: 1998-12-11, release date: 2000-01-19, Last modification date: 2023-08-23)

Primary citation

Helland, R.,Berglund, G.I.,Otlewski, J.,Apostoluk, W.,Andersen, O.A.,Willassen, N.P.,Smalas, A.O.
High-resolution structures of three new trypsin-squash-inhibitor complexes: a detailed comparison with other trypsins and their complexes.
Acta Crystallogr.,Sect.D, 55:139-148, 1999

PubMed Abstract: An anionic trypsin from Atlantic salmon and bovine trypsin have been complexed with the squash-seed inhibitors, CMTI-I (Cucurbita maxima trypsin inhibitor I, P1 Arg) and CPTI-II (Cucurbita pepo trypsin inhibitor II, P1 Lys). The crystal structures of three such complexes have been determined to 1.5-1.8 A resolution and refined to crystallographic R factors ranging from 17.6 to 19.3%. The two anionic salmon-trypsin complexes (ST-CPTI and ST-CMTI) and the bovine-trypsin complex (BT-CPTI) have been compared to other trypsin-inhibitor complexes by means of general structure and primary and secondary binding features. In all three new structures, the primary binding residue of the inhibitor binds to trypsin in the classical manner, but with small differences in the primary and secondary binding patterns. Lysine in CPTI-II binds deeper in the specificity pocket of bovine trypsin than lysine in other known lysine-bovine-trypsin complexes, and anionic salmon trypsin lacks some of the secondary binding interactions found in the complexes formed between squash inhibitors and bovine trypsin. The ST-CMTI complex was formed from the reactive-site-cleaved form of the inhibitor. However, well defined electron density was observed for the P1-P1' peptide bond, together with a hydrogen-bonding pattern virtually identical to those of all serine-protease-protein-inhibitor complexes, indicating a resynthesis of the scissile bond.

PubMed: 10089404
DOI: 10.1107/S090744499801052X

Experimental method

X-RAY DIFFRACTION (1.5 Å)