Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Single-chain toxin is enzymatically converted into two-chain isotoxins which differ from the precursor by their higher pharmacological activity, acidity and hydrophilicity. The interchain disulfide bridge and the disulfide loop within fragment C have been located at the amino acid level. 2. Independent of the enzymes used, the nicking sites are positioned within a region spanning no more than 17 amino acids. The N- and C-termini of the primary gene product are preserved in the two-chain toxin. The chains have been separated by isoelectric focussing and can be reconstituted to functionally intact toxin. 3. Light chain inhibits neurotransmitter release on different systems. First, permeabilized bovine adrenal chromaffin cells and rat pheochromocytoma (PC 12) cells release catecholamines when exposed to micromolar [Ca2+]. Inhibition is achieved with light chain or reduced two-chain toxin, but not with single-chain toxin or heavy chain. Washing away the light chain does not restitute the Ca2(+)-evoked release. The light chains of tetanus and botulinum A toxin act in a apparently similar, however not identical manner. Second, light but not heavy chain inhibits the release of acetylcholine when injected into Aplysia neurones. 4. The pharmacology of heavy chain is quite different. Ganglioside binding is mediated by its fragment C moiety, and modulated by the adjoining beta 2 piece and by light chain. Heavy chain and to a lesser degree its N-terminal beta 2-fragment promote the loss of calcein from liposomes indicating pore formation. Its C-terminal fragment C is inactive in this respect.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Chains and fragments of tetanus toxin, and their contribution to toxicity. 207 46

Sea hares such as Aplysia californica, gastropod molluscs lacking a protective shell, can release a purple cloud of chemicals when vigorously attacked by predators. This active chemical defense is composed of two glandular secretions, ink and opaline, both of which contain an array of compounds. This secretion defends sea hares against predators such as California spiny lobsters Panulirus interruptus via multiple mechanisms, one of which is phagomimicry, in which secretions containing feeding chemicals attract and distract predators toward the secretion and away from the sea hare. We show here that ink and opaline are highly acidic, both having a pH of approximately 5. We examined if the acidity of ink and opaline affects their phagomimetic properties. We tested behavioral and electrophysiological responses of chemoreceptor neurons in the olfactory and gustatory organs of P. interruptus, to ink and opaline of A. californica within their natural range of pH values, from approximately 5 to 8. Both behavioral and electrophysiological responses to ink and opaline were enhanced at low pH, and low pH alone accounted for most of this effect. Our data suggest that acidity enhances the phagomimetic chemical defense of sea hares.
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PMID:Acidity enhances the effectiveness of active chemical defensive secretions of sea hares, Aplysia californica, against spiny lobsters, Panulirus interruptus. 1791 33