Use of a snake venom toxin to characterize the cholinergic receptor protein

alpha-Bungarotoxin, a polypeptide of mol wt 8000 purified from the venom of Bungarus multicinctus, blocks irreversibly and specifically the excitation by cholinergic agonists on the isolated electroplax and on purified membrane fragments in vitro. The toxin also blocks the in vitro binding of decamethonium to a protein recently isolated from electric tissue. This observation strengthens our earlier conclusion that this protein is the cholinergic receptor macromolecule.

Gas Chromatographic Determination of Pyrrolidonecarboxylic Acid

An analytical method is described for analysis of 2-pyrroIidone-5-carboxylic acid (PCA) in foods. PCA was extracted with ethyl acetate, using a modified Widmark extraction apparatus, and then silylated with trimethylchlorosilane and hexamethyldisilazane in the presence of pyridine. The trimethylsilylated PCA derivative was separated by gas-liquid chromatography on a 6′ × 1/4″ °d stainless steel column of 3% SE-30 on Gas Chrom Q and detected with a flame ionization detector. Recovery of PCA was 94-108%. This procedure is a relatively simple and rapid analytical method as compared to the conventional methods.