Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of different calcium-entry blockers, sialidase and caffeine on the biphasic contraction induced by prostaglandin (PG) F2 alpha in the feline basilar artery (BA) were studied in calcium-free medium. After incubation in calcium-free solution, PGF2 alpha induced a contraction of the BA amounting to 87% of the contraction in calcium-containing solution. The response was biphasic in 41 out of 42 vessel segments. PGF2 alpha-induced contractions were markedly attenuated in TRIS-buffered solutions as compared to contractions in Krebs solution. PGF2 alpha failed to induce a biphasic contraction (8 out of 9 preparations) in calcium-free HEPES-buffered solution. Calcium entry blockade with 1 mM manganese or 10(-5) M diltiazem abolished the second and major phase of the PGF2 alpha-induced contraction in calcium-free Krebs solution. The second contraction phase was also eliminated in four out of five preparations pretreated with sialidase (1 unit/ml for 30 min.), but was unaffected by a brief exposure to 20 mM caffeine in calcium-free medium. The present findings strongly support previous suggestions that a major part of the PGF2 alpha-induced contraction in calcium-free medium is mediated via the release of calcium bound to the exterior aspect of the cell membrane.
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PMID:Cellular calcium and the contraction induced by prostaglandin F2 alpha in feline cerebral arteries. 392 1

Sialidases (EC 3.2.1.18) are commonly found in viruses, bacteria, fungi, protozoa, and vertebrates, but not in invertebrates. We have previously reported the presence of a new sialidase activity in the gut of exclusively hematophagous insects of the Triatoma genus, which transmit Chagas' disease (Amino, R., Acosta, A., Morita, O. M., Chioccola, V. L. P., and Schenkman, S. (1995) Glycobiology 5, 625-631). Here we show that this sialidase is present in the salivary gland of Triatoma infestans, and it is released with the saliva during the insect bite. The sialidase was purified to homogeneity (>5000 times) to a specific activity of more than 20 units/mg. It elutes from a gel filtration column with a volume corresponding to the size of 33 kDa, and it migrates as a single 26-kDa band in SDS-polyacrylamide gel electrophoresis, which is unusually smaller when compared with other known sialidases. T. infestans sialidase hydrolyzes preferentially alpha2-->3-linked sialic acids at pH 4-8, with maximal activity between pH 5.5 and 6.5, which is compatible with the optimal pH of secreted sialidases. The sialidase is competitively inhibited by 2-deoxy-2, 3-dehydro-N-acetyl-neuraminic acid (Ki = 0.075 mM) and differently from many sialidases, with exception of Salmonella typhimurium sialidase, it is inhibited competitively by HEPES (Ki = 15 mM). The fact that T. infestans sialidase is released with the saliva and can hydrolyze sialyl-LewisX blood groups, which are the ligands for selectins, suggests that it might have a role in the blood feeding.
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PMID:Identification and characterization of a sialidase released by the salivary gland of the hematophagous insect Triatoma infestans. 973 52