Formation of Bowman-Birk inhibitors during the germination of horsegram (Dolichos biflorus).
Three Bowman-Birk type inhibitors (HGGI-I, II and III), which appear in the cotyledons of 120 h germinated horsegram (Dolichos biflorus) seeds have been purified to homogeneity by size-exclusion chromatography and ion-exchange chromatography. HGGI-I, HGGI-II and HGGI-III differ from each other and from the dormant seed inhibitors in amino acid composition, molecular size and charge. The amino-terminal sequence analyses indicate that these inhibitors are derived from the isoinhibitors of the dormant seed by a limited proteolysis and not by de novo synthesis. These inhibitors differ from each other at their amino-terminus. HGGI-II identical to HGGI-I except for the loss of a single amino-terminal aspartyl residue, where as HGGI-III shows the loss of a pentapeptide. All the three inhibitors are potent competitive inhibitors of trypsin and chymotrypsin. The dissociation constants (K(i)s) for trypsin inhibition indicate that amino-terminal tail of the inhibitors play a role in trypsin binding probably through electrostatic interaction.
Department of Protein Chemistry and Technology, Central Food Technological Research Institute, Mysore 570 013, India.
Pradeep
P
Kumar
Yadahalli N
YN
Sreerama
Lalitha R
LR
Gowda
D000595:Amino Acid Sequence; D002918:Chymotrypsin / Q000187:drug effects; D007887:Fabaceae / Q000378:metabolism*; D018525:Germination / Q000502:physiology*; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012639:Seeds / Q000378:metabolism*; D014357:Trypsin / Q000187:drug effects*; D014361:Trypsin Inhibitors / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology
D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin