Refined Crystal Structure of the Molecular Complex of Streptomyces griseus Protease B, a Serine Protease, with the Third Domain of the Ovomucoid Inhibitor from Turkey

• Published in: Proceedings of the National Academy of Sciences - PNAS 1982-08, Vol.79 (16), p.4868-4872
• Main Authors: Fujinaga, Masao, Read, Randy J., Sielecki, Anita, Ardelt, Wojciech, Laskowski, Michael, Michael N. G. James
• Format: Article
• Language: English
• Subjects: Active sites; Amino acids; Animals; Atoms; Binding Sites; Chemical bonding; Covalent bonds; Crystal structure; Crystallization; Egg Proteins; Endopeptidases; Enzymes; Hydrogen bonds; Molecules; Ovomucin; ovomucoids; Oxygen; Protein Binding; Protein Conformation; Serine Endopeptidases; serine proteinase; Streptomyces griseus; trypsin inhibitor (pancreatic); Turkeys; X-Ray Diffraction
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.79.16.4868

We have determined the crystal structure of the molecular complex between Streptomyces griseus protease B (SGPB), a bacterial serine protease, and the third domain of the ovomucoid inhibitor from turkey. Restrained-parameter least-squares refinement of the structure with the 1.8- angstrom intensity data set has resulted in an R factor of 0.125. The carbonyl carbon atom of the reactive bond between Leu-18 and Glu-19 in the inhibitor lies at a distance of 2.71 angstrom from the Oγatom of the nucleophilic Ser-195 in SGPB; this distance is 0.5 angstrom shorter than a normal van der Waals contact. Unlike the reactive bond in the pancreatic trypsin inhibitor complexed with bovine trypsin, the Leu--Glu bond of the ovomucoid inhibitor is not distorted from planarity towards a pyramidal configuration.