Structural requirements for the edema-inducing and hemolytic activities of mastoparan B isolated from the hornet (Vespa basalis) venom.
Mastoparan B (MP-B) is a cationic tetradecapeptide isolated from the black-bellied hornet (Vespa basalis) venom. It has a primary structure (LKLKSIVSWAKKVL-CONH2) distinct from other vespine mastoparans. The peptide caused a dose-dependent swelling in rat hind paw and showed a potent hemolytic activity in guinea pig red blood cells. Studies on the structure activity relationship of the peptide showed that replacing lysine at position 2 (Lys2) by asparagine (Asn) in the MP-B sequence caused about 40% decrease in its edema-inducing activity at 50 micrograms/paw and 90% decrease in hemolytic activity at 30 microM of the peptide, while the same substitution at Lys4 did not cause a significant change in either activity. Replacing either Lys11 or Lys12 by leucine (Leu) caused little or no decrease in the edema-inducing and hemolytic activities. Decreases in both activities were observed when both Lys11 and Lys12 were replaced by Leu. On the other hand, replacing tryptophan at position 9 (Trp9) by tyrosine or phenylalanine in MP-B sequence almost abolished its hemolytic activity, while the edema-inducing activity was only partially inhibited. Circular dichroism spectra of the peptides measured in 20% trifluoro-ethanol revealed that substitution of Lys and Trp did not cause a significant change in the conformation of MP-B. it appears that Lys2 is crucial for both hemolytic and edema-inducing activities of MP-B, while Trp9 is of special importance to the hemolytic activity of MP-B. Lys11 and Lys12 in MP-B probably play a lesser role in both activities.
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.
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D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D004487:Edema / Q000139:chemically induced; D004912:Erythrocytes / Q000187:drug effects; D006168:Guinea Pigs; D006461:Hemolysis / Q000187:drug effects; D036341:Intercellular Signaling Peptides and Proteins; D008239:Lysine / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013329:Structure-Activity Relationship; D014363:Tryptamines / Q000378:metabolism; D014862:Wasp Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*
D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014363:Tryptamines; D014862:Wasp Venoms; C081223:mastoparan B; C030820:tryptamine; D008239:Lysine