Discriminatory recognition of membrane phospholipids by lysine-49-phospholipases A2 from Trimeresurus flavoviridis venom

✍ Scribed by Yasuyuki Shimohigashi; Ayoko Tani; Yoko Yamaguchi; Tomahisa Ogawi; Motonori Ohno

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 551 KB
• Volume: 9
• Category: Article
• ISSN: 0952-3499
• DOI: 10.1002/(sici)1099-1352(199634/12)9:5/6<639::aid-jmr313>3.0.co;2-x

✦ Synopsis

Basic proteins I and I1 (BP-I and BP-11) isolated from Tnmeresurusflavoviridis venom, which are classified into a group of lysine-49-phospholipases A2 (Lys-49-PLA3, exhibited only limited lipolytic activity for the mixed micelles of various phospholipids. Based on the finding that BP-11 elicits a strong contraction of guinea pig ileum due to the release of arachidonic acid, BP-11 together with BP-I has been tested for their interaction with artificial phospholipid bilayer membranes. The dye leakage experiments indicated that BP-I1 interacts strongly with liposomes of &arachidonoyl-y-stearoyl-L-cu-phosphatidylcholine. The perturbation of liposomes was observed only in the Ca2+-containing buffer, and as demonstrated by HPLC analyses, accompanied by the release of arachidonic acid. The concentration of Ca2+ which gave a half maximal activity of BP-I1 was 3.0 x lov4 M, suggesting that the affinity of BP-11 for Ca2+ is more than 10 times stronger than that of BP-11 without liposomes. These observations clearly show that Lys-49-PLA2 of BP-I1 is the enzyme responsible for the hydrolysis of membrane phospholipids and that Ca2+ is essential for such enzymatic activity. The interaction of BP-I with liposomes was much weaker than BP-II. BP-I and BP-11 share a common sequence except for Asp-67 (BP-I) and Asn-67 in the aligned sequences. This implies that the amino acid at position 67 of Lys-49-PLAs is the residue required for discriminatory recognition of phospholipid membranes.