br Conclusion P gingivalis expresses various exopeptidases i

Conclusion P. gingivalis expresses various exopeptidases, i.e., DPP4, DPP5, DPP7, DPP11, PtpA, and AOP, in periplasmic space, which produce di- and tri-peptides from most oligopeptides. This oligopeptide processing step is important as an extracellular event in the HBX 41108 of asaccharolytic P. gingivalis. Rgp and Kgp are also involved in dipeptide production. An organized subcellular localization of various exopeptidases and gingipains is a rational explanation for processing of proteinaceous nutrients present in the subgingival environment, thus providing a means of efficient survival for the bacterium.
Additional note To activate studies of DPPs of P. gingivalis and other oral bacteria, we contacted the Peptide Institute (Osaka, Japan) to produce DPP substrates. As a result, Leu-Asp- and Met-Leu-MCA, substrates for DPP11 and DPP7, respectively, have recently become available (The Peptide Institute, Supplemental Product List 28-3, 2015).
Conflict of interest
Acknowledgements We thank Dr. R. Kamijyo (Showa University) for providing us the opportunity to present this article. This study was conducted in collaboration with Drs. T. Ono, T.T. Baba, and T. Kobayakawa (Nagasaki University), Dr. S.M.A. Rouf (Faculty of Applied Sciences, Islamic University, Bangladesh), and Drs. Y. Shimoyama and S. Kimura (Iwate Medical University). This study was supported by Grants-in-aid for Scientific Research from the Japan Society for the Promotion of Science (to T.K.N. and Y.O.-N.), a grant from the Institute for Fermentation, Osaka (to T.K.N.), and grants from the Joint Research Promotion Project of Nagasaki University Graduate School of Biomedical Sciences in 2013 and 2014 (to Y.O.-N.).
Introduction Ginseng (Panax ginseng Meyer), which belongs to the genus Panax in the Araliaceae family, has long been used as a traditional herbal medicine [1–3]. Wild ginseng is grown in wild environments without artificial intervention, while the growth conditions of cultivated ginseng are artificially controlled. The medicinal components of ginseng reach stable levels only when the ginseng has matured. Because of their different genotypes and growth environments, wild ginseng and cultivated ginseng have different ages of maturity. Wild ginseng takes a long time to mature (> 30 yrs), and cultivated ginseng only needs 5–6 yrs to mature [4]. Thus, cultivated ginseng has been widely employed to meet the market demand for wild ginseng. Ginseng has a wide range of pharmacological activities, including stress reduction, homeostasis, immunomodulation, antifatigue, antiaging, and anticancer effects [5–9]. However, there are some significant differences in the medicinal functions between wild and cultivated ginseng. The biologically active components of ginseng mainly include ginsenosides, polysaccharides, fatty acids, and amino acids [10]. A recent study showed that the amino acids of ginseng are candidate therapeutic agents with antidepressant, blood pressure reduction, immunity strengthening, and myocardium- and liver-protective activities. Previous studies have indicated that the total and essential amino acid contents of wild ginseng are 2.4- and 1.9-fold higher compared with cultivated ginseng. Thus, there are notable differences between wild ginseng and cultivated ginseng at the amino acid level. However, the mechanism of these differences and their effect on the medical functions of ginseng are not well understood. Proteomics can directly address many biological questions by revealing the abundance of specific proteins within organisms. Traditionally, two-dimensional polyacrylamide gel electrophoresis (2DE) has been the gold standard for proteomic analysis. However, this platform is limited by protein identification and quantification capabilities [11]. Isotope tags for relative and absolute quantification (iTRAQ) reagent coupled with matrix-assisted laser desorption/ionization-time of flight/time of flight (MALDI-TOF/TOF) MS analysis can identify proteins that 2DE fails to separate, such as membrane proteins and low abundance proteins [12]. Thus, iTRAQ could be a good complement to 2DE. Recently, proteomic analysis has been performed to reveal the regulatory mechanism of plant amino acid metabolism. The 2DE approach has been used to study amino acid metabolism between different genotypes of Arabidopsis[13]. Amino acid metabolism has been found to play an important role in the protein synthesis, photosynthesis, and development of Arabidopsis. Moreover, proteomic analysis of the differential molecular responses of rice and wheat coleoptiles to anoxia has revealed the potential role of amino acid biosynthesis in cellular anoxia tolerance [14]. Thus, a proteomic approach could be used to examine the mechanism underlying the difference in amino acid metabolism between wild ginseng and cultivated ginseng.