versity, Osaka, Japan) . Histrioniootoxins : Roentgen-ray analysis of the novel allenic andacetylenic spiroalkaloids isolated from a Colombian frog, Dendrobates hLatrionicus . Proc. Nat.

Acad. Sci. U.S.A . 68, 1870,1971 .

TBIE nRucTupES and absolute configurations oftwo alkaloids isolated fromthe Colombian frog, Dendrobateshistrionicus have been elucidated by X-ray crystallography. Histrionicotoxin is (2,R, 6S, 7PS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis-2-penten4-ynyl)-1-azaspiro(5-5)undecane, while in dihydroisohistrio-nicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent .The histrionicotoxins represent the first examples of acetylenic and allenic alkaloids in the animal kingdom;also, the spiral-ring system of the histrionicotoxins has no precedent in nature. The skin contains about 0-6mg of various alkaloids. The proportions of histrionicotoxin, dihydroisohistrionicotoxin, and another majoralkaloid of unknown structure are 13 :9 :6 . Dendrobatid frogs haveelaborateda variety ofalkaloids containingstructural features unprecedentedin nature, and exploration oftheentire spectrum ofpoisonous skin secretionsin this family is expectedtoelucidateimportant aspectsofthe taxonomy, ecology, andevolution ofthese frogs.

P.R.S.

MORTni ARo, N. A.andHoRN,L. (CollegeofMedicineandDentistry ofNew Jersey at Newark,Newark, N.J., U.S.A.). Vascular response of the cat intestine to norepinephrine following

infusion oftetrodotoxin (ITX). The Physiologist 14,AuTOPERFusED loops of ileum in eviscerated and adrenalectomized cats were intra-arterially infused withnorepinephrine (1-2-5 i<g per min) before and after infusion of TTX (10 Wg per min) . TIX inhibitedsympathetic activity in the perfused segment as indicated by a constant blood flow during splanchnic nervestimulation. The vasoconstrictor response to norepinephrine was potentiated by TTX. It is concluded in thisabstract that a condition resembling denervation hypersensitivity develops within minutes after the infusionofTTX.

P.R.

MEes,D., NAiaTA,K., IwANGA, S., SAmEymA, Y. and LEE, C. Y. (Osaka University, Institute ofProtein Research, Osaka, Japan) . Amino acid sequence of a-bungarotoxin from the venom of

Bungarus multicinctus. Biochem. Biophys. Res. Comm . 44, 711, 1971 .

TimPRuiARYstructure of a-bungarotoxin isolated fromthe venomofBungarus multicinctus was determined.Itcomposes of 74 amino acid residues including ten half-cystines . Comparing the sequence with that of cobra-neurotoxins and of sea snake toxins striking similarities can be found, especially between Naja nivea a-toxinconsisting of71 residues and a-bungarotoxin . If deletions of the two residues at the positions 14 and 15 andofthe one residue at the position 22 in the primary structure of a-bungarotoxin are considered, 37 residuesincluding the location of the ten half-cystines are identical between Naja nivea a-toxin and a-bungarotoxin .Similar homologies among the other neurotoxins mentioned above (61-62 residues per molecule) and a-bungarotoxin are also observed : 24to 27 residues are identical if deletions concerning the half-cystine residuesare made. Moreover, in all neurotoxins, especially the locations of tyrosine-24, lysine-26 and tryptophane-28areexactly thesame, which seemtobecloselyrelatedto theirbiological activity and tertiary structure.

W.K.

SpApsoN, J. W. and RmElt, L. J. (Universityof Texas, DentalScience Institute, Houston, Texas,77025). Collagenolytic activity from venom of the rattlesnake Crotahis atrox . Proc. Soc. exp.

Biol. Med. 137, 893,1971 .

Crotalus atrox venom reduced the viscosity of three different preparations of collagens in solution. Theacrylamide gel electrophoretic patterns derived from reaction mixtures containing collagen and venom pre-parations also showed collagen degradation . These observations, in conjunction with the fact that Crotalusatrox venom degrades mesenteric collagen fibers, indicate specific collagenase activity from Crotalus atroxvenom. Collagenolytic activityof Crotalus atroxvenom priortolow pH exposure resulted inthe conversion ofß-chains to a-chains and the formation of a fragment which traveled beyond the a-chain on acrylamide gelsduring electrophoresis.The electrophoreticpattern obtained fromreaction mixturescontainingvenomexposedtopH2-5, showeda reduction ofboth a-and ß-chains, with at least two fragments appearing betweenthe a-andß-chainsandseveral fragmentsbelowthea-chains.Theobserved differences in electrophoreticpatterns betweenthe two venom preparations indicate that at least two enzymatic activities contribute to the reduction inviscosity of collagen solutions.

W.K

TOXICON 1972 Vol. 10 .