Purification and modes of antifungal action by Vicia faba cv. Egypt trypsin inhibitor.
A new 15 kDa Bowman-Birk type trypsin inhibitor (termed VFTI-E1) from fava beans (Vicia faba cv. Egypt 1) was isolated using liquid chromatography. Though it exhibited substantial homology in N-terminal amino acid sequence to other protease inhibitors, VFTI-E1 showed antiproteolytic activity against trypsin (K(i) 11.9 × 10(-9) M) but hardly any activity against chymotrypsin. It demonstrated antifungal activity toward the filamentous fungus Valsa mali with an IC(50) of 20 μM. The mechanism of its antifungal action toward V. mali included (1) induction of alteration of hyphal morphology, (2) growth inhibition by chitin deposition at hyphal tips, and (3) permeabilization of fungal membrane. The antifungal activity of VFTI-E1 was dependent on the ambient ionic strength as increasing concentrations of NaCl, CaCl(2), and MgCl(2) diminished the activity. The membranolytic action of VFTI-E1 was confined to fungus, but not exerted on human and rabbit erythrocytes. This study sheds light on the mode of hyphal growth inhibitory activity of protease inhibitors with antifungal activity. The antifungal activity of VFTI-E1 amplifies the scope of its potential applications.
Fang
Evandro Fei
EF
School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
Hassanien
Abdallah Abd Elazeem
AA
Wong
Jack Ho
JH
Bah
Clara Shui Fern
CS
Soliman
Saeed Saad
SS
Ng
Tzi Bun
TB
D000595:Amino Acid Sequence; D000818:Animals; D004912:Erythrocytes / Q000187:drug effects; D005659:Fungicides, Industrial / Q000494:pharmacology*; D006801:Humans; D025301:Hyphae / Q000187:drug effects; D003904:Mitosporic Fungi / Q000187:drug effects; D008969:Molecular Sequence Data; D011817:Rabbits; D012639:Seeds / Q000737:chemistry*; D016415:Sequence Alignment; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D031307:Vicia faba / Q000737:chemistry*
D005659:Fungicides, Industrial; D014361:Trypsin Inhibitors