title: Wheat germ trypsin inhibitors. Isolation and structural characterization of single-headed and double-headed inhibitors of the Bowman-Birk type.
abstract: A number of trypsin inhibitors were isolated from wheat germs by affinity chromatography on immobilized trypsin, gel-filtration, and ion-exchange and reverse-phase chromatography. These inhibitors were classified into two groups, inhibitors I (Mr = 14,500) and II (Mr = 7,000), based on their molecular sizes. Inhibitors I and II inhibited bovine trypsin stoichiometorically at an enzyme to inhibitor ratio of 2 and 1, respectively. Sequence analysis of these inhibitors indicated a high degree of homology and that inhibitors I had a duplicated structure of inhibitors II. They are highly homologous to double-headed proteinase inhibitors (Bowman-Birk inhibitors) of Leguminosae plants. Inhibitors II are the first example of single-headed inhibitor corresponding to one inhibitory domain of the Bowman-Birk type double-headed inhibitors, which suggests that inhibitors II are relic of an ancestral single-headed inhibitor before the gene-duplication that led to the formation of present-day Bowman-Birk type inhibitors.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D007700:Kinetics; D008970:Molecular Weight; D010940:Plant Proteins; D013329:Structure-Activity Relationship; D014908:Triticum; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D010940:Plant Proteins; D014361:Trypsin Inhibitors; C051542:wheat germ trypsin inhibitor; D014357:Trypsin