A new protein inhibitor of trypsin and activated hageman factor from pumpkin (Cucurbita maxima) seeds

FEBS Letters

Gong, YuXi¹  Richardson, Michael²  Krishnamoorthi, Ramaswamy¹ 

[1] Department of Biochemistry, Kansas State University, Manhattan, KS 66506, USA;Department of Biological Sciences, University of Durham, Durham, UK

关键词: Inhibitor;    Serine protease;    Cucurbita maxima;    Pumpkin;    Trypsin;    Activated Hageman factor;    Blood coagulation;    CMTI;    Cucurbita maxima trypsin inhibitor;    HPLC;    high performance liquid chromatography;    NMR;    nuclear magnetic resonance spectroscopy;    BAPNA;    Benzoyl-L-Arg-p-nitroanilide;    S-2302;    D-Pro-Phe-Arg-p-nitroanilide;    TFA;    trifluoroacetic acid;    SDS;    sodium dodecyl sulfate;    DABITC;    4-N;    N-dimethylaminoazo-benzene-4'-isothiocyanate;    PITC;    phenylisothiocyanate;   

DOI  :  10.1016/0014-5793(90)81075-Y

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A protein inhibitor (CMTI-V; M _r 7106) of trypsin and activated Hageman factor (Factor XII_a), a serine protease involved in blood coagulation, has been isolated for the first time from pumpkin (Cucurbita maxima) seeds by means of trypsin-affinity chromatography and reverse phase high performance liquid chromatography (HPLC). The dissociation constants of the inhibitor complexes with trypsin and Factor XII_a have been determined to be 1.6 × 10⁻⁸ and 4.1 × 10⁻⁸ M, respectively. The primary structure of CMTI-V is reported. The protein has 68 amino acid residues and one disulfide bridge and shows a high level of sequence homology to the Potato I inhibitor family. Furthermore, its amino terminus consists of an N-acetylates Ser. The reactive site has been established to be the peptide bond between Lys⁴⁴-Asp⁴⁵. The modified inhibitor which has the reactive site peptide bond hydrolyzed inhibits trypsin but not the Hageman factor.

【 授权许可】

Unknown