RESUMO
Two SDS-resistant endochitinases, designated as ASCHI53 and ASCHI61, were isolated from Aeromonas schubertii in a soil sample from southern Taiwan. MALDI-TOF mass measurement indicates the molecular weights of 53,527 for ASCHI53 and 61,202 for ASCHI61. N-terminal and internal amino acid sequences were obtained, and BLAST analysis of the sequences and MS/MS peptide sequencing showed that they were novel proteins. Degradation of chitin by these two endochitinases gave rise to hexameric chitin oligosaccharide, a compound known to have several potent biomedical functions. ASCHI53 and ASCHI61 retained, respectively, 65% and 75%, of their chitinase activity in the presence of 5% SDS and 100% of their activity in the presence of 10% beta-mercaptoethanol. These results demonstrate that they are SDS-resistant endochitinases and probably have a rigid structure.
Assuntos
Aeromonas/enzimologia , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Quitinases/isolamento & purificação , Quitinases/metabolismo , Ativação Enzimática/efeitos dos fármacos , Dodecilsulfato de Sódio/farmacologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrometria de Massas em TandemRESUMO
Cross-talk between TGF-beta and IL-6 has been shown to direct the differentiation of CD4(+) cells into special IL-17-secreting cells, which are termed Th17 cells. In this study, we demonstrated that TGF-beta and IL-6 could stimulate CD8(+) cells to differentiate into noncytotoxic, IL-17-producing cells in MLC. These IL-17-producing CD8(+) cells exhibit a unique granzyme B(-)IFN-gamma(-)IL-10(-) phenotype. The mRNA level of Th2/T cytotoxic 2 (Tc2) transcription factors GATA3 and Th1/Tc1 transcription factors T-box expressed in T cell (T-bet) as well as its target H2.O-like homeobox (Hlx) is decreased in CD8(+) cells from TGF-beta- and IL-6-treated MLC. In addition, these CD8(+) cells display a marked up-regulation of retinoic acid-related orphan receptor-gammat, a key IL-17 transcription factor. These results demonstrate that the existence of an IL-17-producing CD8(+) subset belongs to neither the Tc1 nor the Tc2 subset and can be categorized as a T noncytotoxic 17 (Tnc17) subset.
