Identification of Binding Sites in Copper(II)-Peptide Complexes Using Infrared Spectroscopy.

Complex formation of the copper(II) ion (CuII) with histidine (H) and H-containing peptides plays a crucial role in various metallo-enzymatic reactions. To elucidate the nature of coordinate bonding in CuII complexes, Fourier-transform infrared spectroscopy and 2D IR spectroscopy were employed to investigate the coordination geometries of CuII with diglycine, l-histidylglycine (HG), glycyl-l-histidine (GH), and glycylglycyl-l-histidine. The coordination of CuII to different peptide groups, including the peptide N- and C-termini, the amide group, and the imidazole of the H side chain, exhibits distinct spectral features. The derived molecular structure of the CuII-HG complex based on these spectral features significantly differs from that of CuII-GH, suggesting a preference of the N-terminus and the steric hindrance of the H side chain in CuII chelation.

[Phylogenetic diversity of cultivable bacteria during the brewing process of the luzhou-flavor liquor in Yibin, Sichuan province, China].

OBJECTIVE: In order to better understand the diversity of cultivable bacteria during the brewing process of the Luzhou-flavor liquor in Yibin, and to collect potential microbial resources. METHOD: The cultivable bacteria were isolated by using modified nutrient agar medium and Gogan-I medium, and then analyzed the 16S rRNA gene sequences of the 603 non-redundant isolates separated from the air of fermentation workshop, Pit mud, Zaopei, Chinese Qu and air of Qu workshop sampled from 6 luzhou-flavor liquor production enterprise in Yibin. RESULTS: Phylogenetic analysis based on 16S rRNA gene sequences showed that 599 of them belonged to 101 species of 34 genera, and 4 isolates with < 97% sequence similarities to their closely related members were presumed to be potential novel species. Bacillus is the most dominant genus with 315 strains; Streptomyces, Staphylococcus and Lysinibacillus were dominant genera, with 121, 45 and 35 strains, respectively. The number of isolates belong to the other 31 genera were less than 10 strains, furthermore, only one strain was detected in 16 genera. CONCLUSION: Bacteria during the brewing process of the Luzhou-flavor liquor in Yibin present plentiful diversity and relative stability.