THE SEQUENCE AND X-RAY STRUCTURE OF THE TRYPSIN FROM FUSARIUM-OXYSPORUM

The trypsin from Fusarium oxysporum is equally homologous to trypsins from Streptomyces griseus, Streptomyces erythraeus and to bovine tryps in. A DFP (diisopropylfluorophosphate) inhibited form of the enzyme ha s been crystallized from 1.4 M Na2SO4, buffered with citrate at pH 5.0 -5.5. The crystals belong to space group P2(1) with cell parameters a = 33.43 angstrom, b = 67.65 angstrom, c = 39.85 angstrom and beta = 10 7.6-degrees. There is one protein molecule in the asymmetric unit. X-r ay diffraction data to a resolution of 1.8 angstrom were collected on film using synchrotron radiation. The structure was solved by molecula r replacement using models of bovine and S.griseus trypsins and refine d to an R-factor of 0.141. The overall fold is similar to other trypsi ns, with some insertions and deletions. There is no evidence of the di valent cation binding sites seen in other trypsins. The covalently bou nd inhibitor molecule is clearly visible.