Comparison of phospholipase activity with direct and indirect lytic effects of animal venoms upon human red cells

Biochemical characterization of the phospholipase A2 purified from the venom of the Mexican beaded lizard (Heloderma horridum horridum Wiegmann)

A phospholipase A2 was isolated from the venom of the mexican beaded lizard (Heloderma horridum horridum) by phenyl-Sepharose chromatography followed by Sephadex G-75 gel filtration and two additional steps on ion exchange resins (DE-32 cellulose). The affinity chromatographic method (PC-Sepharose 4B) reported for the isolation of other phospholipases [Rock, Ch. O., & Snyder, F. (1975) J. Biol. Chem. 250, 2564-2566; King, T. P., Alagon, A. C., Kwan, J., Sobotka, A. K., & Lichteinstein, L. M. (1983) Mol. Immunol. 20, 297-308; King, T. P., Kochoumian, L., & Joslyn, A. (1984) Arch. Biochem. Biophys. 230, 1-12] was uneffective for the separation of this enzyme. The monomeric form of the Heloderma phospholipase has an apparent Mr of 18 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 19 060 as calculated from amino acid analysis. It also contains on the order of 7% carbohydrates per mole of enzyme. The N-terminal amino acid sequence was shown to be very different from that of phospholipases isolated from mammalian pancreas and crotalids and elapids snake venoms. The first 39 amino acid residues at the N-terminal region have 56% homology with bee venom phospholipase but differ from the bee phospholipase in that its isoelectric point is acidic (pI = 4.5), instead of basic, and it has approximately 50 amino acid residues more in the molecule. The specificity of the enzyme is mainly A2 type with possible residual B-type activity. The enzymatic activity is Ca2+-dependent. Half-cystine alignment of the Heloderma phospholipase sequence with those of other known phospholipases shows the lack of an octadecapeptide at the N-terminal region, the existence of an extra hexapeptide at positions 42-47, and an exact correspondence of Heloderma Gly-12, Gly-14, His-36, and Asp-37 with Gly-30, Gly-32, His-48, and Asp-49 from other phospholipases shown to be important for Ca2+ binding (( Dijkstra, B. W., Drenth, J., Kalk, K. H., & Vandermaalen, P. J. (1978) J. Mol. Biol. 124, 53-60 )).(ABSTRACT TRUNCATED AT 250 WORDS)

Venom from the snake Bothrops asper Garman. Purification and characterization of three phospholipases A2

The water-soluble venom of Bothrops asper Garman (San Juan Evangelista, Veracruz, México) showed 15 polypeptide bands on polyacrylamide-gel electrophoresis. This material exhibited phospholipase, hyaluronidase, N-benzoyl-l-arginine ethyl hydrolase, N-benzoyl-l-tyrosine ethyl hydrolase and phosphodiesterase activity, but no alkaline phosphatase or acid phosphatase activity. Fractionation on Sephadex G-75 afforded seven protein fractions, which were apparently less toxic than the whole venom (LD(50)=4.3mug/g mouse wt.). Subsequent separation of the phospholipase-positive fraction (II) on DEAE-cellulose with potassium phosphate buffers (pH7.55) gave several fractions, two being phospholipase-positive (II.6 and II.8). These fractions were further purified on DEAE-cellulose columns with potassium phosphate buffers (pH8.6). Fraction II.8.4 was rechromatographed in the same DEAE-cellulose column, giving a pure protein designated phospholipase 1. The fraction II.6.3 was further separated by gel disc electrophoresis yielding two more pure proteins designated phospholipase 2 and phospholipase 3. Analysis of phospholipids hydrolysed by these enzymes have shown that all three phospholipases belong to type A(2). Amino acid analysis has shown that phospholipase A(2) (type 1) has 97 residues with a calculated mol.wt. of 10978+/-11. Phospholipase A(2) (type 2) has 96 residues with a mol.wt. of 10959+/-11. Phospholipase A(2) (type 3) has 266 residues with 16 half-cystine residues and a calculated mol.wt of 29042+/-31. Automated Edman degradation showed the N-terminal sequence to be: Asx-Leu-Trp-Glx-Phe-Gly-Glx-Met-Met-Ser-Asx-Val- Met-Arg-Lys-Asx-Val-Val-Phe-Lys-Tyr-Leu- for phospholipase A(2) (type 2).