title: Interaction of trypsin, beta-factor XIIa, and plasma kallikrein with a trypsin inhibitor isolated from barley seeds: a comparison with the corn inhibitor of activated Hageman factor.
abstract: A trypsin inhibitor was purified from barley seeds by a modification of published procedures. We determined the dissociation constant, Ki, for the complexes of the barley inhibitor with trypsin, beta-Factor XIIa, and plasma kallikrein. We compared these constants for those of the same enzymes with the corn Hageman Factor inhibitor, which is a homolog of the barley inhibitor. The strength of interaction of the barley inhibitor with the three enzymes was: trypsin greater than beta-Factor XIIa greater than plasma kallikrein. In contrast, the corn inhibitor inhibits beta-Factor XIIa most strongly and does not inhibit plasma kallikrein at all. A possible structural basis for the difference in inhibition specificity is discussed.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D002523:Edible Grain / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D005174:Factor XII / Q000378:metabolism* / Q000494:pharmacology*; D015956:Factor XIIa; D001467:Hordeum / Q000737:chemistry*; D006801:Humans; D007610:Kallikreins / Q000032:analysis*; D010940:Plant Proteins / Q000032:analysis; D012697:Serine Endopeptidases / Q000378:metabolism*; D012967:Sodium Dodecyl Sulfate; D014361:Trypsin Inhibitors / Q000032:analysis / Q000494:pharmacology*; D003313:Zea mays / Q000737:chemistry
chemical_list: D000596:Amino Acids; C114195:CHF1 protein, Zea mays; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D012967:Sodium Dodecyl Sulfate; D005174:Factor XII; D007610:Kallikreins; D012697:Serine Endopeptidases; D015956:Factor XIIa