1PPE

THE REFINED 2.0 ANGSTROMS X-RAY CRYSTAL STRUCTURE OF THE COMPLEX FORMED BETWEEN BOVINE BETA-TRYPSIN AND CMTI-I, A TRYPSIN INHIBITOR FROM SQUASH SEEDS (CUCURBITA MAXIMA): TOPOLOGICAL SIMILARITY OF THE SQUASH SEED INHIBITORS WITH THE CARBOXYPEPTIDASE A INHIBITOR FROM POTATOES

Summary for 1PPE

• Entry DOI: 10.2210/pdb1ppe/pdb
• Descriptor: TRYPSIN, TRYPSIN INHIBITOR CMTI-I (3 entities in total)
• Functional Keywords: serine proteinase, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Bos taurus (cattle)
• Cellular location: Secreted, extracellular space: P00760; Secreted: P01074
• Total number of polymer chains: 2
• Total formula weight: 26604.21

Authors

Bode, W.,Huber, R. (deposition date: 1991-10-24, release date: 1994-01-31, Last modification date: 2024-10-23)

Primary citation

Bode, W.,Greyling, H.J.,Huber, R.,Otlewski, J.,Wilusz, T.
The refined 2.0 A X-ray crystal structure of the complex formed between bovine beta-trypsin and CMTI-I, a trypsin inhibitor from squash seeds (Cucurbita maxima). Topological similarity of the squash seed inhibitors with the carboxypeptidase A inhibitor from potatoes
FEBS Lett., 242:285-292, 1989

PubMed Abstract: The stoichiometric complex formed between bovine beta-trypsin and the Cucurbita maxima trypsin inhibitor I (CMTI-I) was crystallized and its X-ray crystal structure determined using Patterson search techniques. Its structure has been crystallographically refined to a final R value of 0.152 (6.0-2.0 A). CMTI-I is of ellipsoidal shape; it lacks helices or beta-sheets, but consists of turns and connecting short polypeptide stretches. The disulfide pairing is CYS-3I-20I, Cys-10I-22I and Cys-16I-28I. According to the polypeptide fold and disulfide connectivity its structure resembles that of the carboxypeptidase A inhibitor from potatoes. Thirteen of the 29 inhibitor residues are in direct contact with trypsin; most of them are in the primary binding segment Val-2I (P4)-Glu-9I (P4') which contains the reactive site bond Arg-5I-Ile-6I and is in a conformation observed also for other serine proteinase inhibitors.

PubMed: 2914611
DOI: 10.1016/0014-5793(89)80486-7

Experimental method

X-RAY DIFFRACTION (2 Å)