Passiflin, a novel dimeric antifungal protein from seeds of the passion fruit.
The intent was to isolate an antifungal protein from seeds of the passion fruit (Passiflora edulis) and to compare its characteristics with other antifungal proteins and bovine beta-lactoglobulin in view of its N-terminal amino acid sequence similarity to beta-lactoglobulin. The isolation procedure entailed ion-exchange chromatography on Q-Sepharose, hydrophobic interaction chromatography on Phenyl-Sepharose, ion-exchange chromatography on DEAE-cellulose, and FPLC-gel filtration on Superdex 75. The isolated 67-kDa protein, designated as passiflin, exhibited an N-terminal amino acid sequence closely resembling that of bovine beta-lactoglobulin. It is the first antifungal protein found to have a beta-lactoglobulin-like N-terminal sequence. Its dimeric nature is rarely found in antifungal proteins. It impeded mycelial growth in Rhizotonia solani with an IC(50) of 16 microM and potently inhibited proliferation of MCF-7 breast cancer cells with an IC(50) of 15 microM. There was no cross-reactivity of passiflin with anti-beta-lactoglobulin antiserum. Intact beta-lactoglobulin lacks antifungal and antiproliferative activities and is much smaller in molecular size than passiflin. However, it has been reported that hydrolyzed beta-lactoglobulin shows antifungal activity. The data suggest that passiflin is distinct from beta-lactoglobulin.
Lam
S K
SK
Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. lamszekwan@yahoo.com.hk
Ng
T B
TB
D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy; D002417:Cattle; D045744:Cell Line, Tumor; D005658:Fungi / Q000187:drug effects*; D006801:Humans; D007782:Lactoglobulins / Q000494:pharmacology*; D008969:Molecular Sequence Data; D029598:Passiflora; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology / Q000627:therapeutic use; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D012639:Seeds
D000935:Antifungal Agents; D007782:Lactoglobulins; D010936:Plant Extracts; D010940:Plant Proteins; C539927:passiflin protein, Passiflora edulis