Seroreactivity to Pep19 of P. gingivalis HSP60, an oral pathogen, was predominant in patients with autoimmune disease with ongoing periodontal disease.
The xyl1 gene encoding xylose reductase was cloned from Saccharomyces cerevisiae and expressed in Escherichia coli. The purified enzyme readily carried out xylose reduction in vitro. It prefers NADPH as the co-enzyme by about 80-fold over NADH. Compared to the native enzyme purified from S. cerevisiae (Kuhn et al., 1995), the recombinant xylose reductase displayed slightly higher (about two-fold) affinities (K(m)) for the substrate (xylose) and co-factor (NADPH), as well as a 3.9-fold faster turnover number (K(cat)) and 7.4-fold greater catalytic efficiency (K(cat)/K(m)). The reason for the apparent discrepancies in kinetic constants between the recombinant and native S. cerevisiae xylose reductases is not known. Replacement of Tyr49 by Phe in the recombinant enzyme led to greater than 98% loss of activity, suggesting that this residue plays a critical role in catalysis. Intrinsic enzyme fluorescence spectroscopic analysis showed that the wild-type and the Y49F variant both bound the co-enzyme NADPH with similar affinity. This supports the view that Tyr49 is involved in interaction with the substrate and not the co-factor during catalysis.
Taken together, epitope spreading to Hu19, Hu9 and ox-LDL provoked by Pep19 could be proposed as a solid phenomenon observed in P. gingivalis-induced chronic periodontitis and infection-induced autoimmune diseases in a reproducible and predictable manner. T-cell proliferative activity to these peptides and cross-reactivity of anti-Pep19 antibodies to multiple human autoantigens could be proposed as cellular and molecular mechanisms responsible for this phenomenon.
The synthesis of dimethyl carbonate (DMC) was investigated through the transesterification of propylene carbonate (PC) with methanol using quaternary ammonium salt catalysts. The reaction was carried out in an autoclave at 120-140 o C under carbon dioxide pressure of 250-400 psig. The main by-product was propylene glycol. The quaternary salts of larger alkyl group and more nucleophilic counter anion exhibited higher catalytic activity. Kinetic studies were also performed to better understand the reaction mechanism. Quaternary ammonium chlorides immobilized on polystyrene supports were also tested for their possible uses as heterogeneous catalysts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.