Fluorescence kinetics of flavin adenine dinucleotide in different microenvironments

Fluorescence kinetics of flavin adenine dinucleotide was measured in a wide time and spectral range in different media, affecting its intra- end extramolecular interactions, and analyzed by a new method based on compressed sensing

Improved system for heterologous expression of cytochrome c mutants in Escherichia coli

We improved an already existing cytochrome c expression system to a reliable, tightly controllable one to achieve a higher expression yield for single cysteine mutants of horse cytochrome c. The protein is heterologously overexpressed in E. coli together with the maturation coordinating enzyme heme lyase from yeast. Various plasmid constructs and host strains were tested for protein expression yield and routinely around 35 mg/L yield was achieved, which is a good result for a post-translationally modified enzyme. The purpose of producing cysteine mutants is to position accessible cysteine residues on the surface of cytochrome c which can be labeled with a photoactive redox dye, 8-thiouredopyrene-1,3,6-trisulfonate, TUPS. TUPS labeled proteins have been used for intramolecular and intermolecular electron transfer measurements. Here, we initiate the photoreduction of cytochrome c oxidase, the natural electron acceptor partner of cytochrome c by an appropriate cytochrome c mutant labeled with TUPS. The electron transfer from cytochrome c to the first cytochrome oxidase redox cofactor, copper A, is shown to be very fast

Utilization of keratin-containing biowaste to produce biohydrogen.

A two-stage fermentation system was constructed to test and demonstrate the feasibility of biohydrogen generation from keratin-rich biowaste. We isolated a novel aerobic Bacillus strain (Bacillus licheniformis KK1) that displays outstanding keratinolytic activity. The isolated strain was employed to convert keratin-containing biowaste into a fermentation product that is rich in amino acids and peptides. The process was optimized for the second fermentation step, in which the product of keratin fermentation--supplemented with essential minerals--was metabolized by Thermococcus litoralis, an anaerobic hyperthermophilic archaeon. T. litoralis grew on the keratin hydrolysate and produced hydrogen gas as a physiological fermentation byproduct. Hyperthermophilic cells utilized the keratin hydrolysate in a similar way as their standard nutrient, i.e., bacto-peptone. The generalization of the findings to protein-rich waste treatment and production of biohydrogen is discussed and possible means of further improvements are listed

Overlaps between the various biodegradation pathways in Sphingomonas subarctica SA1

A bacterium capable to grow on sulfanilic acid as sole carbon, nitrogen and sulfur source has been isolated. A unique feature of this strain is that it contains the full set of enzymes necessary for the biodegradation of sulfanilic acid. Taxonomical analysis identified our isolate as Sphingomonas subarctica SA1 sp. The biodegradation pathway of sulfanilic acid was investigated at the molecular level. Screening the substrate specificity of the strain disclosed its capacity to degrade six analogous aromatic compounds including p -aminobenzoic acid. Moreover, the strain was successfully used for removal of oil contaminations. S. subarctica SA1 seemed to use distinct enzyme cascades for decomposition of these molecules, since alternative enzymes were induced in cells grown on various substrates. However, the protein patterns appearing upon induction by sulfanilic acid and sulfocatechol were very similar to each other indicating common pathways for the degradation of these substrates. Cells grown on sulfanilic acid could convert p -aminobenzoic acid to some extent and vice versa. Two types of ring cleaving dioxygenases were detected in the cells grown on various substrates: one preferred protocatechol, while the other had higher activity with sulfocatechol. This latter enzyme, named as sulfocatechol dioxygenase was partially purified and characterized