Purification and characterization of the biological effects of phospholipase A 2 from sea anemone Bunodosoma caissarum

Abstract

Sea anemones contain a variety of biologically active substances. Bunodosoma caissarum is a sea anemone from the Cnidaria phylum, found only in Brazilian coastal waters. The aim of the present work was to study the biological effects of PLA 2 isolated from the sea anemone B. caissarum on the isolated perfused kidney, the arteriolar mesenteric bed and on insulin secretion. Specimens of B. caissarum were collected from the São Vicente Channel on the southern coast of the State of São Paulo, Brazil. Reverse phase HPLC analysis of the crude extract of B. caissarum detected three PLA 2 proteins (named BcPLA 21, BcPLA 22 and BcPLA 23) found to be active in B. caissarum extracts. MALDI-TOF mass spectrometry of BcPLA 21 showed one main peak at 14.7 kDa. The N-terminal amino acid sequence of BcPLA 21 showed high amino acid sequence identity with PLA 2 group III protein isolated from the Mexican lizard (PA23 HELSU, HELSU, PA22 HELSU) and with the honey bee Apis mellifera (PLA 2 and 1POC_A). In addition, BcPLA 21 also showed significant overall homology to bee PLA 2. The enzymatic activity induced by native BcPLA 21 (20 μg/well) was reduced by chemical treatment with p-bromophenacyl bromide ( p-BPB) and with morin. BcPLA 21 strongly induced insulin secretion in presence of high glucose concentration. In isolated kidney, the PLA 2 from B. caissarum increased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate, and sodium, potassium and chloride levels of excretion. BcPLA 21, however, did not increase the perfusion pressure on the mesenteric vascular bed. In conclusion, PLA 2, a group III phospholipase isolated from the sea anemone B. caissarum, exerted effects on renal function and induced insulin secretion in conditions of high glucose concentration.