Abstract— A series of retinals with specific structural alterations have been synthesized to probe the bacteriorhodopsin binding site. The 4‐chloro‐, 4‐bromo‐ and 4‐iodoretinals all form pigments with bacterioopsin but undergo an in situ displacement of the allylic halogen to form the 4‐hydroxyretinal pigment. Several naphthyl retinals were prepared which effectively extend the polyene chain and/or add bulk to the ring portion of the chromophore. All the naphthyl retinals form pigments with bacterioopsin but only the pigment containing the derivative with a polyene side chain identical to that of retinal pumps protons efficiently. The 12‐butyl‐13‐desmethylretinal was also synthesized but this analogue did not form a pigment with bacterioopsin. These results confirm the nonspecificity at the ring portion of the chromophore binding site and the importance of the role of the polyene chain in the proton pumping function of bacteriorhodopsin.

Improper use of pesticides on food plants can result in significant toxicity. In spite of regulations, enforcement, and prior episodes of poisonings, poisonings from misapplication of pesticides continues to occur. The objective of this study was to present a case series of toxicity resulting from ingestion of watermelon inappropriately treated with the carbamate insecticide aldicarb. A restrospective review of medical records, impounding the suspected watermelons, and chemical analysis of the watermelon samples using liquid chromatography and mass spectroscopy were carried out. Seven farm workers shared a watermelon and presented to a rural emergency department with symptoms of cholinergic poisoning. They were treated empirically with atropine and pralidoxime. The farmer denied use of insecticides other than rat poison on the watermelon patch. Chemical analyst verified aldicarb in the watermelon samples from the field, but none in control samples. Despite government regulations, application of restricted pesticides such as aldicarb continues to occur and cause significant poisonings.

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