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| Anéas,M.A.F.; Portaro,F.C.V.; Lebrun,I.; Juliano,L.; Palma,M.S.; Fernandes,B.L.. |
| The opportunistic bacterium Proteus mirabilis secretes a metalloprotease, ZapA, considered to be one of its virulence factors due to its IgA-degrading activity. However, the substrate specificity of this enzyme has not yet been fully characterized. In the present study we used fluorescent peptides derived from bioactive peptides and the oxidized ß-chain of insulin to determine the enzyme specificity. The bradykinin- and dynorphin-derived peptides were cleaved at the single bonds Phe-Ser and Phe-Leu, with catalytic efficiencies of 291 and 13 mM/s, respectively. Besides confirming already published cleavage sites, a novel cleavage site was determined for the ß-chain of insulin (Val-Asn). Both the natural and the recombinant enzyme displayed the same broad... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Proteus mirabilis; Metalloprotease; Substrate specificity; Fluorogenic peptides; IgA; Insulin ß-chain. |
| Ano: 2001 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2001001100004 |
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| Fernandes,B.L.; Anéas,M.A.F.; Juliano,L.; Palma,M.S.; Lebrun,I.; Portaro,F.C.V.. |
| The protease ZapA, secreted by Proteus mirabilis, has been considered to be a virulence factor of this opportunistic bacterium. The control of its expression requires the use of an appropriate methodology, which until now has not been developed. The present study focused on the replacement of azocasein with fluorogenic substrates, and on the definition of enzyme specificity. Eight fluorogenic substrates were tested, and the peptide Abz-Ala-Phe-Arg-Ser-Ala-Ala-Gln-EDDnp was found to be the most convenient for use as an operational substrate for ZapA. A single peptide bond (Arg-Ser) was cleaved with a Km of 4.6 µM, a k cat of 1.73 s-1, and a catalytic efficiency of 376 (mM s)-1. Another good substrate for ZapA was peptide 6... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Metalloprotease; Substrate specificity; Quenched fluorescence peptides; Proteus mirabilis. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000700006 |
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| Kaur,Jatinder; Chadha,Bhupinder S; Kumar,Badhan A; Kaur,Ghatora, S; Saini,Harvinder S. |
| This study reports the purification and characterization of ß-glucosidase from a newly isolated thermophilic fungus, Melanocarpus sp. Microbial Type Culture Collection (MTCC) 3922. The molecular weight of ß-glucosidase was determined to be ~ 92 and 102 kDa with SDS PAGE and gel filtration, respectively, and pI of ~ 4.1. It was optimally active at 60ºC and pH 6.0, though was stable at 50ºC and pH 5.0 - 6.0. The presence of DTT, mercaptoethanol and metal ions such as Na+, K+, Ca2+, Mg2+and Zn2+ positively influenced the activity of ß-glucosidase but the activity was inhibited in the presence of CuSO4. ß-Glucosidase recognized pNP- ß-glucopyranoside (pNPG) as the preferred substrate, and showed very low affinity for pNP- ß-D-cellobioside. Km and Vmax for the... |
| Tipo: Journal article |
Palavras-chave: SS-glucosidase; Melanocarpus sp; Purification; Substrate specificity; Transglycosylation. |
| Ano: 2007 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000200010 |
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