The dehydroshikimate dehydratase (DSD) from Corynebacterium glutamicum encoded by the qsuB gene is related to the previously described QuiC1 protein (39.9% identity) from Pseudomonas putida. Both QuiC1 and QsuB are two-domain bacterial DSDs. The N-terminal domain provides dehydratase activity, while the C-terminal domain has sequence identity with 4-hydroxyphenylpyruvate dioxygenase. Here, the QsuB protein and its N-terminal domain (N-QsuB) were expressed in the T7 system, purified and characterized. QsuB was present mainly in octameric form (60%), while N-QsuB had a predominantly monomeric structure (80%) in aqueous buffer. Both proteins possessed DSD activity with one of the following cofactors (listed in the order of decreasing activity): Co 2+ , Mg 2+ , Mn 2+. The K m and k cat values for the QsuB enzyme (K m~1 mM, k cat~6 1 s-1) were two and three times higher than those for N-QsuB. 3,4-DHBA inhibited QsuB (K i~0 .38 mM, K i '~0.96 mM) and N-QsuB (K i~0 .69 mM) enzymes via mixed and noncompetitive inhibition mechanism, respectively. E. coli MG1655ΔaroEP lac-qsuB strain produced three times more 3,4-DHBA from glucose in test tube fermentation than the MG1655ΔaroEP lac-n-qsuB strain. The C-terminal domain activity towards 3,4-DHBA was not established in vitro. This domain was proposed to promote protein oligomerization for maintaining structural stability of the enzyme. The dimer formation of QsuB protein was more predictable (ΔG =-15.8 kcal/mol) than the dimerization of its truncated version N-QsuB (ΔG =-0.4 kcal/mol).

We propose a fluorescence method for protein content assessment in fine house dust, which can be used as an indicator of the hygienic state of occupied rooms. The results of the measurements performed with 30 house dust samples, including ultrafiltration experiments, strongly suggest that the fluorescence emission of house dust extracts excited at 350 nm is mainly due to protein fragments, which are presumably keratin hydrolysates. This suggestion is supported by several facts: (i) Spectral band shapes for all the samples under investigation are close and correspond to that of keratin; (ii) fluorescence intensity correlates with the total protein content as provided by Lowry assay; (iii) treatment of the samples with proteinase K, which induces keratin hydrolysis, results in fluorescence enhancement without changing fluorescence band shape; and (iv) Raman spectra of keratin and fine house dust samples exhibit a very similar structure. Based on the obtained results and literature data, we propose a hypothesis that keratin is a major substrate for fluorescence species in fine house dust, which are responsible for emission at 350-nm excitation.

Herein we report about developing new type of Surface Enhanced Raman Scattering (SERS) substrates based on Au-decorated carbon nanowalls. The designed substrates possess high specific surface area and high sensitivity. Chemical stability of Au perfectly blends with electrical properties and high value of specific surface area of carbon nanowalls. Created structures were applied to detect signals of a typical molecule used for SERS substrates testing, rhodamine 6G, which exhibits electronic absorption in the visible area of spectrum, and biomacromolecules such as tryptophan, guanine, bovine serum albumin and keratin hydrolysates, whose electronic absorption is in the ultraviolet region of spectrum and lies far from the Au plasmonic resonance. The obtained signals for these compounds suggest that the developed substrate is a prominent platform for the detection of biological macromolecules. The properties of the substrate, including its morphology and Au film thickness, as well as the analyte deposition method, were optimized to achieve the optimum Raman signal enhancement. Electric field distribution in the designed structures was calculated to describe the observed dependence of SERS activity on the substrate morphology.

Cyanobacteria bloom is a great ecological problem of Curonian Lagoon and Baltic Sea. The development of novel methods for the on-line control of cyanobacteria concentration and, moreover, for prediction of bloom spreading is of interest for monitoring the state of ecosystem. Here, we report the results of the joint application of hyperspectral measurements and remote sensing of Curonian Lagoon in July 2015 aimed at the assessment of cyanobacteria communities. We show that hyperspectral data allow on-line detection and qualitative estimation of cyanobacteria concentration, while the remote sensing data indicate the possibility of cyanobacteria bloom detection using the spectral features of upwelling irradiation.