N49 phospholipase A2, a unique subgroup of snake venom group II phospholipase A2

A novel phospholipase A(2) (PLA(2)) with Asn at its site 49 was purified from the snake venom of Protobothrops mucrosquamatus by using SP-Sephadex C25, Superdex 75, Heparin-Sepharose (FF) and HPLC reverse-phage C-18 chromatography and designated as TM-N49. It showed a molecular mass of 13.875 kDa on MALDI-TOF. TM-N49 does not possess enzymatic, hemolytic and hemorrhagic activities. It fails to induce platelet aggregation by itself, and does not inhibit the platelet aggregation induced by ADP. However, it exhibits potent myotoxic activity causing inflammatory cell infiltration, severe myoedema, myonecrosis and myolysis in the gastrocnemius muscles of BALB/c mice. Phylogenetic analysis found that that TM-N49 combined with two phospholipase A(2)s from Trimeresurus stejnegeri, TsR6 and CTs-R6 cluster into one group. Structural and functional analysis indicated that these phospholipase A(2)s are distinct from the other subgroups (D49 PLA(2), S49 PLA(2) and K49 PLA(2)) and represent a unique subgroup of snake venom group II PLA(2), named N49 PLA(2) subgroup. (C) 2005 Elsevier B.V. All rights reserved.