Roles of lysine-69 in dimerization and activity of Trimeresurus flavoviridis venom aspartate-49-phospholipase A2

✍ Scribed by Shinji Nakamura; Makoto Nakai; Kin-chi Nakashima; Tomohisa Ogawa; Yasuyuki Shimohigashi; Motonori Ohno; Hiroshi Kihara; Takashi Yamane; Tamaichi Ashida

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 766 KB
• Volume: 9
• Category: Article
• ISSN: 0952-3499
• DOI: 10.1002/(sici)1099-1352(199601)9:1<23::aid-jmr235>3.0.co;2-p

✦ Synopsis

Trimeresurus fivoviridis (Habu snake) venom aspartate-49-phospholipase A2 (Asp-49-PLAz) was reacted at pH 9.0 with a 2-fold molar excess of 2,4,6-trinitrobenzenesdfonate in the absence of Ca" and two trinitrophenylated derivatives were isolated by HPLC. One was a derivative modified at Lys-11 and its activity was mostly retained. The other was a derivative modified at both Lys-11 and Lys-72 and its activity was 40% that of unmodified enzyme. Trinitrophenylation of Lys-72 appeared to bring about a conformational disorder at the lipid-water interface recognition site and thus a reduction of activity. When the enzyme was modiied in the presence of Ca2+, activity decreased at a rate much faster than that in the absence of Ca2+ and Lys-69 came to be modified. These results suggested that conformational displacement of Asp-49-PLA2 of a local to global type occurs upon the binding of Ca2+. The derivative modified at Lys-69 had 28% activity and existed as a monomer. This supports a previous assumption that Lys-69 participates in dimerization of group I1 Asp-49-PLAg [Brunie et al. (1985) J . Bwl. Chem. 260, 974297493 and shows that dimerization is not necessarily essential for activity manifestation.