Accession Number : ADA193994

Title :   Structure-Function Relationship of Hydrophiidae Postsynaptic Neurotoxins.

Descriptive Note : Annual rept. 1 Mar 87-28 Feb 88,

Corporate Author : COLORADO STATE UNIV FORT COLLINS DEPT OF BIOCHEMISTRY

Personal Author(s) : Tu, Anthony T

PDF Url : ADA193994

Report Date : 29 Feb 1988

Pagination or Media Count : 30

Abstract : This annual report is comprised of two main parts: A. The major neurotoxin from the venom of Acalyptophis peronii captured in the Gulf of Thailand was isolated. Although there are two toxic fractions in the venom, the most toxic and abundant fraction was selected for purification and chemical characterization. The LD50 of the major toxin is 0.125 micrograms/g mice, indicating an extremely toxic nature. The toxin consists of 60 amino acid residues with methionine as the amino-terminal and asparagine as the carboxy-terminal end. It contains nine half-cystine residues. There is 1 mol each of tryptophan, tyrosine, methionine, valine, aspartic acid, leucine, and alanine, and there is no phenylalanine. The molecular weight calculated from the amino acid sequence determination was 6600. The toxin replaces alpha-bungarotoxin in binding with the acetylcholine receptor, indicating that the A. peronii major neurotoxin competes with alpha-bungarotoxin for the same binding site of the acetylcholine receptor. B. The acetylcholine receptor connects the nerve impulse from the axon to the muscle by receiving a nerve transmitter, acetylcholine. The receptor consists of five subunits of which two are identical. It is known that the subunit is the site for the acetylcholine binding and also for its antagonist, snake postsynaptic neurotoxin. It is generally recognized that the subunits beta, gamma and alpha are also essential to maintain the integrity of the acetylcholine receptor. In order to further understand the role of the subunits in the acetylcholine receptor function, the subunits were cross-linked with dimethyl suberimidate.

Descriptors :   *TOXINS AND ANTITOXINS, ACETYLCHOLINE, ALANINES, AMINO ACIDS, ASPARTIC ACID, CNS DEPRESSANTS, DETERMINATION, LEUCINE, METHIONINE, MOLECULAR WEIGHT, MUSCLES, NERVE FIBERS, NERVES, PHENYLALANINE, SENSE ORGANS, SEQUENCES, SITES, TRYPTOPHAN, TYROSINE, VENOMS, SNAKES

Subject Categories : Toxicology

Distribution Statement : APPROVED FOR PUBLIC RELEASE