Chemical replacement of P1' arginine residue at the first reactive site of peanut protease inhibitor B-III.
The contribution of the P1' residue at the first reactive site of peanut protease inhibitor B-III to the inhibition was analyzed by replacement of the P1' Arg(11) with other amino acids (Arg, Ser, Ala, Leu, Phe, Asp) after selective modification of the second reactive site. The Arg derivative had the same trypsin inhibitory activity as the native inhibitor (Ki = 2 X 10(-9) M). The Ser derivative inhibited more weakly (Ki = 2 X 10(-8) M). The Ala and Leu derivatives inhibited trypsin very weakly (Ki = 2 X 10(-7) M and 4 X 10(-7) M, respectively), and the Phe and Asp derivatives not at all. These results suggest that the P1' arginine residue is best for inhibitory activity at the first reactive site of B-III, although it has been suggested that a P1' serine residue at the reactive site is best for inhibitory activity of Bowman-Birk type inhibitors.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001120:Arginine / Q000378:metabolism*; D010940:Plant Proteins; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000378:metabolism*
D000596:Amino Acids; D010940:Plant Proteins; D014361:Trypsin Inhibitors; C037954:trypsin-chymotrypsin inhibitor B-III, peanut; D001120:Arginine; D014357:Trypsin