Purification and Characterization of a Tripeptidase from Lactococcus lactis subsp. cremoris Wg2
AUTOR(ES)
Bosman, Boukje W.
RESUMO
A tripeptidase from a cell extract of Lactococcus lactis subsp. cremoris Wg2 has been purified to homogeneity by DEAE-Sephacel and phenyl-Sepharose chromatography followed by gel filtration over a Sephadex G-100 SF column and a high-performance liquid chromatography TSK G3000 SW column. The enzyme appears to be a dimer with a molecular weight of between 103,000 and 105,000 and is composed of two identical subunits each with a molecular weight of about 52,000. The tripeptidase is capable of hydrolyzing only tripeptides. The enzyme activity is optimal at pH 7.5 and at 55°C. EDTA inhibits the activity, and this can be reactivated with Zn2+, Mn2+, and partially with Co2+. The reducing agents dithiothreitol and β-mercaptoethanol and the divalent cation Cu2+ inhibit tripeptidase activity. Kinetic studies indicate that the peptidase hydrolyzes leucyl-leucyl-leucine with a Km of 0.15 mM and a Vmax of 151 μmol/min per mg of protein.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=184519Documentos Relacionados
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