Serine proteinase from Cucurbita ficifolia seed; purification, properties, substrate specificity and action on native squash trypsin inhibitor (CMTI I)
A proteinase was purified from resting seeds of Cucurbita ficifolia by ammonium sulfate fractionation and successive chromatography on CM-cellulose, (Sephacryl) S-300 and TSK DEAE-2SW (HPLC) columns. Inhibition by DFP and PMSF suggests that the enzyme is a serine proteinase. The apparent molecular m...
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Published in | Biological chemistry Hoppe-Seyler Vol. 371; no. 9; pp. 889 - 895 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Germany
01.09.1990
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Subjects | |
Online Access | Get more information |
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Summary: | A proteinase was purified from resting seeds of Cucurbita ficifolia by ammonium sulfate fractionation and successive chromatography on CM-cellulose, (Sephacryl) S-300 and TSK DEAE-2SW (HPLC) columns. Inhibition by DFP and PMSF suggests that the enzyme is a serine proteinase. The apparent molecular mass of this enzyme is ca. 77 kDa. The optimum activity for hydrolysis of casein and Suc-Ala-Ala-Pro-Phe-pNA is around pH 10.5. The following peptide bonds in the oxidized insulin B-chain were hydrolysed by the proteinase: Phe1-Val2, Asn3-Gln4, Gln4-His5, Cya7-Gly8, Glu13-Ala14, Ala14-Leu15, Cya19-Gly20, Pro28-Lys29 and Lys29-Ala30. The proteinase is more selective towards the native squash seed trypsin inhibitor (CMTII) and primarily cuts off only its N-terminal arginine. The inhibitor devoided of the N-terminal arginine residue is still active against trypsin. |
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ISSN: | 0177-3593 |
DOI: | 10.1515/bchm3.1990.371.2.889 |