Lumazine protein is believed to serve as an optical transponder in bioluminescence emission by certain marine bacteria. Sequence arguments suggest that the protein comprises two similarly folded riboflavin synthase-type domains, but earlier work also suggested that only one domain binds 6,7-dimethyl-8-ribityllumazine (DMRL). We show that the replacement of serine-48 or threonine-50 in the N-terminal domain of lumazine protein of Photobacterium leiognathi modulates the absorbance and fluorescence properties of bound DMRL or riboflavin. Moreover, the replacement of these amino acids is accompanied by reduced ligand affinity. Replacement of serine-48 by tryptophan shifts the (13)C NMR signal of the 6-methyl group in bound DMRL upfield by 2.9 ppm as compared to the wild-type protein complex. Replacement of threonine-50 causes a downfield shift of approximately 20 ppm for the (15)N NMR signal of N-5, as well as an upfield shift of 3 ppm for the (13)C NMR signal of C-7 in bound DMRL, respectively. The replacement of the topologically equivalent serine-144 and proline-146 in the C-terminal domain had no significant impact on optical properties, chemical shifts and apparent binding constants of bound DMRL. These data show that the N-terminal domain is the unique site for ligand binding in lumazine protein.

While a mixture of residential and non-residential uses in urban development has advantages in reducing transportation energy consumption and improving efficiency of land utilization, the patterns of energy consumption in mixed-use buildings are largely unknown. To understand associations between the built environment and energy consumption and to find effective strategies for energy saving, this study aims to examine how the gas and electricity energy consumption of mixed-use properties is influenced by the characteristics of the immediate surroundings of the building as well as by the building's attributes. The sample for this study is 22,109 mixed-use buildings in Seoul, Korea and the main source of outcome is electricity and gas energy consumption data retrieved from the open system of building data in 2015 and 2016. The regression results showed that a higher proportion of non-residential uses in mixed-use buildings was positively associated with higher electricity consumption overall but that it reduced gas energy use during the winter. In particular, increased restaurant and service use significantly influenced electricity consumption in the buildings. With regard to surrounding built environment, higher impervious surfaces and dense development near the buildings increased the electricity consumption of the buildings but it reduced gas energy consumption. Our results imply that, through the mediating effects of UHIs, the built environment characteristics of immediate surroundings may have indirect effects on energy consumption in mixed-use buildings.

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