title: Studies on the status of lysine residues in phospholipase A2 from Naja naja atra (Taiwan cobra) snake venom.
abstract: Phospholipase A2 (PLA2) from Naja naja atra (Taiwan cobra) snake venom was subjected to lysine modification with trinitrobenzene sulphonic acid (TNBS), and two major trinitrophenylated (TNP) derivatives, TNP-1 and TNP-2, were separated by h.p.l.c. TNP-1 contained only one TNP group on Lys-6 and showed a marked decrease in enzymic activity, but still retained 45% of the lethal toxicity. Both Lys-6 and Lys-65 were modified in TNP-2, and modification of Lys-65 caused a further reduction of the lethal toxicity to 12.6%. However, the antigenicity of both TNP-1 and TNP-2 remained unchanged. The reactivity of Lys-6 and Lys-65 toward TNBS was greatly enhanced by Ca2+ and dihexanoyl-lecithin, suggesting that the two Lys residues are not directly involved in the binding of Ca2+ and substrate. The modified derivatives retained their affinity for Ca2+, indicating that Lys-6 and Lys-65 did not participate in the Ca2+ binding. The TNP derivatives could be regenerated with hydrazine hydrochloride. The biological activities of the regenerated PLA2 are almost the same as those of native PLA2. These results indicate that Lys-6 and Lys-65 are important for the biological activities of PLA2, and incorporation of a bulky TNP group on Lys-6 and Lys-65 might give rise to a distortion of the active conformation of PLA2.
authors.affiliation: Institute of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors.forename: C C
authors.initials: CC
authors.lastname: Yang
authors.forename: L S
authors.initials: LS
authors.lastname: Chang
mesh_terms: D000818:Animals; D002118:Calcium; D002851:Chromatography, High Pressure Liquid; D004546:Elapid Venoms / Q000032:analysis*; D008239:Lysine / Q000032:analysis*; D010740:Phospholipases / Q000032:analysis*; D010741:Phospholipases A / Q000032:analysis*; D054467:Phospholipases A2; D011487:Protein Conformation; D014302:Trinitrobenzenesulfonic Acid
chemical_list: D004546:Elapid Venoms; D014302:Trinitrobenzenesulfonic Acid; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D008239:Lysine; D002118:Calcium