Crystallization and main-chain structure of neutral protease from Streptomyces caespitosus.
A neutral protease, i.e., a zinc-containing metalloendoprotease from Streptomyces caespitosus, has been crystallized using acetone as a precipitating agent. The crystals diffract to better than 1.5 A resolution when a rotating anode X-ray generator is used as an X-ray source. Protein phase angles were calculated by the multiple isomorphous replacement method using two heavy-atom derivatives (HgCl2 and CH3HgCl). A 6 A resolution electron density map clearly showed molecular boundaries. Although its amino acid sequence is not known, the folding pattern of the polypeptide chain could be traced on a 2.5 A resolution electron density map. A large cleft, which is located on the molecular surface, was proved to be the active site of the enzyme by structure analyses of inhibitor-complex crystals. The highest electron density peak, which corresponds to the cleft, was assigned to a catalytically essential zinc atom on difference Fourier synthesis between native and EDTA-soaked crystals.
Department of Applied Chemistry, Faculty of Engineering, Osaka University.
S
S
Harada
K
K
Kitadokoro
T
T
Kinoshita
Y
Y
Kai
N
N
Kasai
D001665:Binding Sites; D008666:Metalloendopeptidases / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D013302:Streptomyces / Q000201:enzymology*; D014961:X-Ray Diffraction
D008666:Metalloendopeptidases; C106507:zinc endoprotease, Streptomyces caespitosus