title: X-ray analysis and circular dichroism of the acid protease from Endothia parasitica and chymosin.
abstract: The structure of an acid proteinase from Endothia parasitica has been solved by x-ray diffraction using multiple isomorphous replacement. A 3 A resolution map was interpreted in terms of a bilobal structure with a long 25 A cleft. The secondary structure is mostly distorted beta-sheet. The circular dichroism was measured and model curves for different secondary structures were fitted by least squares indicating a large component of beta-structure. The structure was seen to be homologous with that of the acid proteinase from R. Chinensis and hence with pepsin and chymosin. A rotation function against diffraction data from chymosin crystals confirm confirm this and suggested an approach to the solution of this structure.
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D012085:Chymosin; D002942:Circular Dichroism; D005583:Fourier Analysis; D008958:Models, Molecular; D010447:Peptide Hydrolases; D011487:Protein Conformation; D014961:X-Ray Diffraction; D013098:Xylariales / Q000201:enzymology*
chemical_list: D010447:Peptide Hydrolases; D012085:Chymosin