title: In vitro activation of the hemolysin in Prevotella nigrescens ATCC 33563 and Prevotella intermedia ATCC 25611.
abstract: Hemolytic activity was evaluated in the putative periodontopathogens Prevotella intermedia and Prevotella nigrescens. Whole cells of both species present weak hemolytic activity evidenced only by solid media assays after 48 h of bacterial growth or after 5 h of interaction with erythrocytes at 37 degrees C in liquid assays. In this work we show that the use of crude extract allowed the detection of a higher hemolytic activity for P. intermedia, but surprisingly not for P. nigrescens. Incubation at 37 degrees C for 9 h, or treatment with trypsin or proteinase K, increased or exposed the hemolytic activity of P. intermedia and P. nigrescens crude extract, respectively. The activation process was inhibited by TLCK and PMSF but not by EDTA, E-64 or pepstatin A, indicating the serino-protease nature of the factor involved in activation of P. intermedia and P. nigrescens hemolysins. Both the buffer and the pH employed for cell fractionation influenced the activation of hemolysin, and the best results were obtained with Universal buffer at pH 8.0. The activated hemolysins acted optimally at pH 6.5 at 37 degrees C and the maximum hemolytic activity was detected at the early log phase of growth. The results of this study show for the first time a strong hemolytic activity for P. nigrescens and evidence of proteolytic activation of hemolysins produced by periodontopathogens.
authors.affiliation: Laboratório de Microbiologia Oral e Anaeróbios, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 Pampulha, CEP 31 270-901, Belo Horizonte, MG, Brazil.
authors.forename: Tarcília Aparecida
authors.initials: TA
authors.lastname: Silva
authors.forename: Fátima Soares M
authors.initials: FS
authors.lastname: Noronha
authors.forename: Luiz
authors.initials: L
authors.lastname: de Macêdo Farias
authors.forename: Maria Auxiliadora R
authors.initials: MA
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D004492:Edetic Acid / Q000494:pharmacology; D019286:Endopeptidase K / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D006460:Hemolysin Proteins / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010436:Pepstatins / Q000494:pharmacology; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D018713:Prevotella intermedia / Q000254:growth & development / Q000378:metabolism*; D045242:Prevotella nigrescens / Q000254:growth & development / Q000378:metabolism*; D011817:Rabbits; D013696:Temperature; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D006460:Hemolysin Proteins; D010436:Pepstatins; D014107:Tosyllysine Chloromethyl Ketone; D010664:Phenylmethylsulfonyl Fluoride; D004492:Edetic Acid; D010450:Endopeptidases; D014357:Trypsin; D019286:Endopeptidase K; D007930:Leucine; C024974:E 64; C031375:pepstatin