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)

Gastric and intestinal phenotypic expression in 37 surgically obtained primary signet ring cell carcinomas, five of their metastases to lymph nodes, and three signet ring cell carcinomas transplanted into nude mice were determined by biochemical, mucin, histochemical, and ultrastructural studies. Crude extracts of cancer tissues were used for measurements of pepsinogen isozymes, sucrase, aminopeptidase (microsomal), and alkaline phosphatase. Histochemical staining of mucin by paradoxical concanavalin A, the galactose oxidase-Schiff sequence and sialidase-galactose oxidase-Schiff, and the periodate-borohydride technique/potassium hydroxide/periodic acid-Schiff procedure was performed. The procedures allowed clear definition of pyloric gland, surface mucous, small and large intestinal goblet, and intestinal absorptive cell types. Of 40 specimens examined, 19 consisted entirely of gastric-type cells, and three entirely of intestinal-type cells. The others consisted of mixtures of gastric and intestinal-type cells. The observed high incidence of intestinal-type cells in signet ring cell carcinomas suggested that intestinal-type cells develop independently from intestinal metaplasia within signet ring cell carcinomas (diffuse-type gastric cancers), which probably originate from nonmetaplastic gastric mucosa.
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PMID:Gastric and intestinal phenotypic expressions of human signet ring cell carcinomas revealed by their biochemistry, mucin histochemistry, and ultrastructure. 301

An acid sialidase [EC 3.2.1.18], partially purified from human placenta by Con A-Sepharose adsorption and p-aminophenyl thio-beta-D-galactoside-CH-Sepharose (PATG-Sepharose) affinity chromatographies, was activated by incubation at 37 degrees C. This activation showed both time and temperature dependencies, with the most effective activation observed at 37 degrees C in the pH range between 4.3 and 5.2. The influence of various protease inhibitors on its activation was investigated. Among the protease inhibitors tested, amastatin, an inhibitor of aminopeptidase A, significantly inhibited activation. The partially purified enzyme preparation contained aminopeptidase activity, which was inhibited by amastatin. Zinc ions inhibited either the activation of sialidase or the aminopeptidase activity in the enzyme preparation. These results suggest the possibility of participation of aminopeptidase function in the activation process of sialidase.
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PMID:Activation of human lysosomal sialidase. 813 49

1. Aminopeptidase Ey from hen's egg yolk contains 1.0 g atom of zinc/mol of a subunit having molecular weight of 150 kDa. The inactive, Zn(2+)-free apoenzyme was reactivated by Co2+, Mn2+, Ca2+, Cd2+, Cu2+ and Ni2+ in addition to Zn2+, whereas Mg2+ and Fe2+ were ineffective. 2. The enzymatical properties of reconstituted enzymes, except for Zn(2+)-reconstituted enzyme, differed from native enzyme. The values for the activation energy were calculated by aminopeptidase Ey and Co(2+)-reconstituted enzyme. 3. The isoelectric point of the enzyme was about 2.8 as determined by isoelectric focusing. An asialo form of the enzyme, obtained by treatment with Arthrobacter sialidase, had an isoelectric point of 4.4. 4. The amino terminal sequence of aminopeptidase Ey was determined to be acyl-Xaa-Xaa-Pro-Glu-Ala-Ala-Ser-Leu-Pro-Gly. There was no identity with any known sequences of aminopeptidase.
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PMID:Molecular properties of aminopeptidase Ey as a zinc-metalloenzyme. 828 37

A 1.4-kb gene encoding the "small" sialidase isoenzyme of Clostridium perfringens A99, including its own promoter, was previously cloned in and expressed by Escherichia coli JM 101. Since all attempts to purify this enzyme to homogeneity were unsuccessful, a new strategy was developed. The structural gene was amplified by means of a PCR technique and inserted into the plasmid vector pQE-10, transferring a six-histidine affinity tag (His6) to the N-terminus of the protein. In order to minimize proteolytic degradation of the sialidase protein, the gene was subcloned into the Escherichia coli strain BL21(DE3)pLys S with reduced protease activity. The sialidase production was increased about 2.5-fold when compared with that of the original clone. The enzyme, released by lysozyme treatment of the bacterial cells, was purified by metal chelate chromatography on Ni-nitrilo-triacetic acid agarose to apparent homogeneity in SDS-PAGE. The 42-kDa protein was enriched 62-fold with a yield of 82% and a specific activity of 280 U mg-1. A total amount of 1 mg sialidase was obtained from 1 liter of bacterial culture. For future studies, including crystallization experiments, the histidine affinity tag was removed from the sialidase enzyme by aminopeptidase K. The sialidase was then separated from aminopeptidase K by ion-exchange chromatography, resulting in an overall yield of 83% and a specific activity of 305 U mg-1 using 4-methylumbelliferyl- alpha-D-N-acetylneuraminic acid under standard conditions. The two forms (with or without the histidine tag) of sialidase exhibited similar kinetic properties when compared to the wild-type enzyme.
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PMID:Expression and purification of a recombinant "small" sialidase from Clostridium perfringens A99. 877 61