Isolation, properties and amino acid sequences of a phospholipase A2 and its homologue without activity from the venom of a sea snake, Laticauda colubrina, from the Solomon Islands

Abstract

A phospholipase A2, Laticauda colubrina phospholipase A2 II (LcPLA-II), and a phospholipase A2 homologue, Laticauda colubrina phospholipase A2 homologue I (LcPLH-I), were isolated from the venom of the yellow-lipped sea snake, Laticauda colubrina, from the Solomon Islands. LcPLA-II showed phospholipase A2 activity towards egg-yolk phosphatidylcholine (24 mumol/min per mg at optimal conditions at 37 degrees C) and lethal potency (LD50 45 micrograms/kg body wt. intravenously in mice). Both of the activities were lost by treatment with p-bromophenacyl bromide. LcPLH-I showed neither phospholipase A2 activity nor lethal potency at a dose of 4.5 mg/kg body wt. in mice. It was not modified by the treatment with p-bromophenacyl bromide. LcPLA-II and LcPLH-I bound Ca2+ at a 1:1 molar ratio with KCa values of 105 microM and 44 microM at pH 8.0 respectively. Elucidation of the amino acid sequences of these two proteins showed that each protein consisted of a single chain of 118 amino acid residues, including 14 half-cystine residues. The two sequences are different from each other at 22 residues and highly homologous to those from other sources. The essential histidine residue for the phospholipase A2 activity at position 48 is replaced by an asparagine residue in the homologue LcPLH-I. Details of the separation of the peptides obtained by proteinase digestions of LcPLA-II and LcPLA-I and the determination of their amino acid sequences are given in Supplementary Publication SUP 50145 (14 pages), which has been deposited at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1988) 249, 5.

Activities of native and tyrosine-69 mutant phospholipases A2 on phospholipid analogs. A reevaluation of the minimal substrate requirements

“…In active PLA,s only once was a different residue, i.e., a phenylalanine, reported in the enzyme from Laticauda colubrina venom (Takasaki et al, 1988). Given the observation that in naturally occurring PLA2s lysine and tyrosine both can be present at this position, the low activity of the Y69K mutant relative to native porcine pancreatic PLA, was unexpected.…”

Sequences, geographic variations and molecular phylogeny of venom phospholipases and threefinger toxins of eastern India Bungarus fasciatus and kinetic analyses of its Pro31 phospholipases A2

“…These enzymes showed very low hydrolytic activities toward various kinds of micelles and mono‐dispersed substrates in vitro (Table 3) [8,27]. Other P31‐PLAs were also found in Australian and marine elapid venoms, including Pa‐13, Pa‐15 from Pseudechis australis , pseudexin B from Pseudechis porphyriacus [28–30], and LcPLH from Laticauda colubrina [31]. They are usually abundant in the venom and show low catalytic activities.…”

Venom Proteome of Spine-Bellied Sea Snake (Hydrophis curtus) from Penang, Malaysia: Toxicity Correlation, Immunoprofiling and Cross-Neutralization by Sea Snake Antivenom

“…Indeed, a handful of venom proteomic studies of sea snakes and a sea krait were in agreement that alpha-neurotoxins and phospholipases A 2 form the dominant proteins in these venoms [12,16,17,18,19,20]. The highly streamlined “minimalist” venom proteomes, however, does not limit the diversity of the toxins: the molecular subtypes, relative abundances and functionality (including toxic activities) of the venom proteins could still vary [14,19,21,22]. This provides the rationale for continuous investigation into the venom proteomes of different sea snake species in order to understand the intra-genus and intra-species diversity and evolution of the toxins.…”