title: Crystal structure of calcium-free proteinase K at 1.5-A resolution.
abstract: Proteinase K from the fungus Tritirachium album Limber binds two Ca2+ ions, one strongly (Ca 1) and the other weakly (Ca 2). Removal of these cations reduces the stability of proteinase K as shown by thermal denaturation, but the proteolytic activity is unchanged. The x-ray structures of native and Ca(2+)-free proteinase K at 1.5-A resolution show that there are no cuts in the polypeptide backbone (i.e. no autolysis), Ca 1 has been replaced by Na+, while Ca 2 has been substituted by a water associated with a larger but locally confined structural change at that site. A small but concerted geometrical shift is transmitted from the Ca 1 site via eight secondary structure elements to the substrate recognition site (Gly100-Tyr104, and Ser132-Gly136) but not to the catalytic triad (Asp39,His69,Ser224). This is accompanied by positional changes of localized waters.
authors.affiliation: Institut für Kristallographie, Freie Universität Berlin, Federal Republic of Germany.
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: W
authors.initials: W
authors.lastname: Hinrichs
authors.forename: W M
authors.initials: WM
authors.lastname: Wolf
authors.forename: W
authors.initials: W
authors.lastname: Saenger
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019286:Endopeptidase K; D004795:Enzyme Stability; D006358:Hot Temperature; D007700:Kinetics; D003904:Mitosporic Fungi / Q000201:enzymology; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000737:chemistry*; D012997:Solvents
chemical_list: D012997:Solvents; D012697:Serine Endopeptidases; D019286:Endopeptidase K; D002118:Calcium