Vertebrate venoms

Neurotoxins from Sea Snake and Other Vertebrate Venoms... 

Neurotoxins present in sea snake venoms are summarized. All sea snake venoms are extremely toxic, with low LD5Q values. Most sea snake neurotoxins consist of only 60-62 amino acid residues with 4 disulOde bonds, while some consist of 70 amino acids with 5 disulfide bonds. The origin of toxicity is due to the attachment of 2 neurotoxin molecules to 2 a subunits of an acetylcholine receptor that is composed of a2 6 subunits. The complete structure of several of the sea snake neurotoxins have been worked out. Through chemical modification studies the invariant tryptophan and tyrosine residues of post-synaptic neurotoxins were shown to be of a critical nature to the toxicity function of the molecule. Lysine and arginine are also believed to be important. Other marine vertebrate venoms are not well known. 

Since sea snake venoms are discussed here, it is appropriate to review other vertebrate venoms also. Unfortunately, very few investigations have been done on the venoms of other marine vertebrates. It is known that some fish secrete venoms from their spines. The fishes known to have venoms are the scorpion fish (family Scorpaenidae), weever fish (family Trachinidae), catfish (order Siluriformes there are 31 families), stargazers (family Uranoscopidae), toad fish (family Batrachoidi-dae), and stingrays (suborder Myliobatoidea). 

From this brief review of marine vertebrate venoms, it is obvious that very few biochemical investigations have been done. The technology to study marine vertebrate venom components is available. There are simply not enough scientists interested enough to enter the field. The first task is to isolate the toxic principles and identify the amino acid sequences. Pharmacological investigation should be done on the purified toxic principle and not on the crude venom, which is a mixture of many proteins and nonproteins. 

Tu, A. T. (1990). Neurotoxins from sea snake and other vertebrate venoms. In Marine Toxins Origin, Structure, and Molecular Pharmacology (S. Hall and G. Strinchartz, eds.). ACS Symp. Ser. 418 336-346. 

The presence of toxins in C. geographus venom which block the response of vertebrate skeletal muscle to direct electrical stimulation was first detected by Endean et al. (14). A toxic component which reversibly blocked the generation of action... 

There are many venomous marine vertebrates in the seas, notably sea snakes and fishes. Venoms of sea snakes have been studied much more thoroughly than fish venoms. In this chapter, sea snake venom is described in greater detail than fish venoms simply because there is much more scientific information available. 

Unless the last-mentioned product is removed by the inclusion of catalase, the oxoacid is liable to react further, undergoing oxidative decarboxylation to the carboxylic acid. An attractive feature of this group of enzymes in the present context is that there exist readily available representatives of both enantiospecificities. The well-studied and commercially available AAOs from vertebrate sources, such as l-AAO from snake venom and D-AAO from pig kidney, are expensive, however, and are increasingly being replaced by enzymes from microbial sources. 

Nucleotidase (5 -ribonucleotide phosphohydrolase, EC 3.1.3.5) is widely distributed in nature and a voluminous literature has appeared in the past decade on the enzyme from vertebrate tissues, seminal fluid, snake venoms, yeasts, and bacteria. Studies regarding the discovery and early investigations of the enzyme have been reviewed by Heppel (1) and... 

Abstract a-Latrotoxin (a-LTX) from black widow spider venom induces exhaustive release of neurotransmitters from vertebrate nerve terminals and endocrine cells. This 130-kDa protein has been employed for many years as a molecular tool to study exocytosis. However, its action is complex in neurons, a-LTX induces massive secretion both in the presence of extracellular Ca2+ (Ca2+e) and in its absence in endocrine cells, it usually requires Ca2+e. To use this toxin for further dissection of secretory mechanisms, one needs an in-depth understanding of its... 

Alkaloid parsimony has also been detected in animals that produce alkaloids. Fire ants in the genus Solenopsis produce venoms dominated by novel 2,6-dialkylpiperidines that are delivered into vertebrates subcutaneously. The venoms constitute outstanding examples of alkaloid parsimony as they provide their ant producers with a diversity of deterrents. The alkaloids cause dermal necrosis in humans and are very algogenic in addition to being very lytic. The piperidines also perturb enzymatic pathways and block neuromuscular junctions. Fire ants have obviously adapted their piperidines to function as extreme exanples of alkaloid parsimony. 

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