Role of conserved arginine in solar energy conversion: Infrared spectroscopy of bacteriorhodopsin, proteorhodopsin, and model compounds

Time-resolved Fourier transform infrared (FT-IR) difference spectroscopy has been used to investigate the photocycles of two membrane proteins, bacteriorhodopsin and proteorhodopsin, that serve as light-driven H + pumps. In the initial studies presented, two programs important for time-resolved FT-IR experiments are described. The first program divides automatically a 9-hour time-resolved FT-IR measurement into any specified sub-measurements; while the second global multi-exponential fit program can extract intermediate spectra and their time constants from time-resolved FT-IR spectra. Further studies have concentrated on understanding the molecular mechanisms of active H + transport in these systems. A characteristic positive band at 1556 cm -1 in the bR[arrow right]M difference spectra, which shows isotopic downshift and pH dependence, is assigned to arg-82 in M; making it likely that arg-82 itself functions as the fast H + -release group in bacteriorhodopsin. Time-resolved FT-IR spectra of proteorhodopsin under conditions that allow so-called fast H + -release suggest that the released H + cannot originate from the Schiff base or asp-97. Since pR lacks homologs of residues glu-194/-204 of bacteriorhodopsin, the highly conserved arg-94 (analog of arg-82 in bacteriorhodopsin) is the strongest candidate for the fast H + -release group in proteorhodopsin. In the last chapter, the vibrational spectra of arg-82 side chain in the M state of bR (arg-94 for pR) is modeled by a deprotonated alkylguanidine group in a nonpolar solvent; and the deprotonated arg-82 at physiological pH is modeled as being stabilized by an indirect H-bond with tyr-83 (tyr-95 for pR)

TIN OXIDE BASED COMPOSITE ANODES FOR LITHIUM ION BATTERIES

Master'sMASTER OF ENGINEERIN

Path Analysis on Environmental Factors Controlling Runoff and Sediment Yields in Shelter Forests in Three Gorges Reservoir Region

Effects of environmental factors such as climate, topography, vegetation and soil in shelter forests in Three Gorges Reservoir Region on runoff and sediment yields were monitored to identify dominant environmental factors controlling runoff and sediment yields in 15 runoff plots in study area by soil sampling, laboratory analysis, stepwise regression analysis and path analysis, and to establish the main control environmental factors that affect runoff and sediment yields. The results showed that soil bulk density, herbaceous cover, slope, and canopy density were the significant factors controlling runoff, and the direct path coefficient of each factor was ranked as canopy closure (-0.628) > litter thickness (-0.547) > bulk density (0.509) > altitude (0.289). The indirect path coefficient was ranked as soil bulk density (0.354) > litter thickness (-0.169) > altitude (0.126) > canopy closure (-0.104). Therefore, canopy closure and litter thickness mainly had direct effects on runoff, while soil bulk density mainly had indirect effects through their contributions to other factors. Herbaceous cover, litter thickness, slope, canopy density, and altitude were the significant factors controlling sediment yields. The direct path coefficient of each factor was ranked as herbaceous cover (-0.815) > litter thickness (-0.777) > canopy closure (-0.624) > slope (0.620). The indirect path coefficient was ranked as slope (0.272) > litter thickness (-0.131) > canopy closure (-0.097) > herbaceous cover (-0.084). Therefore, herbaceous cover and litter thickness mainly had direct effects on sediment yields, while slope mainly had indirect effects through their contributions to other factors. All the selected environmental factors jointly explained 85.5% and 78.3% of runoff and sediment yield variability, respectively. However, there were large values of remaining path coefficients of other factors influencing runoff and sediment yields, which indicated that some important factors are not included and should be taken into account

A novel multiplex assay of SNP-STR markers for forensic purpose.

Like DIP-STR markers (deletion/insertion polymorphism-short tandem repeat combinations), SNP-STR markers (single nucleotide polymorphism-STR combinations) are also valuable in forensic DNA mixture analysis. In this study, eight SNP-STRs were selected, and a stable and sensitive multiplex polymerase chain reaction (PCR) assay was developed for amplifying these SNP-STRs and the Amelogenin gender marker according to the principle of amplification refractory mutation system (ARMS). This novel multiplex set allows detection of the minor DNA contributor in a DNA mixture of any gender and cellular origin with high resolution (beyond a DNA ratio of 1:20). In addition, SNP-STR haplotype frequencies were estimated based on a survey of 350 unrelated individuals from Chinese Han population, and the combined power of discrimination (PD) and power of exclusion (PE) of the eight SNP-STRs were calculated as 0.99999999965 and 0.9996, which were obviously higher than that of the eight STR loci: 0.9999999954 and 0.9989 respectively. The results indicated that the SNP-STR compound markers have higher application value in forensic identification compared to standard autosomal STRs, especially in the analysis of imbalanced DNA mixtures