THE INFLUENCE OF PRELIMINARY GLYCEROL TREATMENT ON SUCCINIC DEHYDROGENASE ACTIVITY OF SKIN CONSERVED THROUGH FREEZING

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AUTORADIOGRAPHIC INVESTIGATION OF METHIONINE S35 INCLUSION IN VARIOUS METHODS OF SKIN CONSERVATION

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CYTOCHEMICAL INVESTIGATIONS OF SKIN WITH A VIEW TO ITS STORAGE : III. Investigations on Protein amino-groups of Skin Preserved in Solutions

No abstract

AN EFFECT OF STORAGE AND TRANSPORTATION TEMPERATURE ON QUANTITATIVE AND QUALITATIVE COMPOSITION OF MICROFLORA OF PLANT PRODUCTS

The results of the study on changes in the composition and quantity of epiphytic and endophytic microorganisms of plant products during storage and transportation are presented. For the investigation, the authors took apple fruits and leafy spicy green products that had biological peculiarities and allowed investigating processes of the long-term and short-term main stages (cold storage, transportation by refrigerated transport, presales storage) of the continuous cold chain on the way to a consumer. Apple fruits were placed in storage in cold chambers with the temperature regimes of plus (2–3)°C and minus (1–2)°C, where they were stored for 90 days. The vegetative organs of dill and parsley were transported during 8 hours by a refrigerated truck and placed in the commercial refrigeration equipment at two temperature regimes (4–5) C and (0–1) C for 72 hours for presales storage. The results of the microbiological analysis showed that the number of endophytic microorganisms (bacteria, yeasts and molds) was lower by 1–3 orders of magnitude in apple fruits and by 2–3 times in green vegetables compared to the number of epiphytic microorganisms. It was established that the regime of storage at negative temperatures completely inhibited the development of epiphytic bacteria on fruits, significantly delayed the multiplication of epiphytic yeasts and molds; while at a positive temperature the number of bacteria increased approximately by 10–17 times, yeasts by 180 times and molds by 3 times. The dynamics of changes in the number of endophytic microorganisms during storage showed the same trend that was observed for epiphytic microorganisms. Analysis of the microbial quantity after transportation of green products showed an increase in abundance of the revealed groups of epiphytes and endophytes by 1.5–3 times upon absolute prevalence of bacteria. After short-term storage, a significant growth of the revealed microbial groups was found; with that, their quantity was 1.5–6.5 times higher at (4–5) C than at (0–1) C. The authors experimentally confirmed the conclusion that with respect to reduction of losses due to microbiological spoilage and extension of shelf life, the cold storage regime of the studied plant products at near-zero temperatures is preferable compared to the regimes of storage at higher positive temperatures.The results of the study on changes in the composition and quantity of epiphytic and endophytic microorganisms of plant products during storage and transportation are presented. For the investigation, the authors took apple fruits and leafy spicy green products that had biological peculiarities and allowed investigating processes of the long-term and short-term main stages (cold storage, transportation by refrigerated transport, presales storage) of the continuous cold chain on the way to a consumer. Apple fruits were placed in storage in cold chambers with the temperature regimes of plus (2–3)°C and minus (1–2)°C, where they were stored for 90 days. The vegetative organs of dill and parsley were transported during 8 hours by a refrigerated truck and placed in the commercial refrigeration equipment at two temperature regimes (4–5) C and (0–1) C for 72 hours for presales storage. The results of the microbiological analysis showed that the number of endophytic microorganisms (bacteria, yeasts and molds) was lower by 1–3 orders of magnitude in apple fruits and by 2–3 times in green vegetables compared to the number of epiphytic microorganisms. It was established that the regime of storage at negative temperatures completely inhibited the development of epiphytic bacteria on fruits, significantly delayed the multiplication of epiphytic yeasts and molds; while at a positive temperature the number of bacteria increased approximately by 10–17 times, yeasts by 180 times and molds by 3 times. The dynamics of changes in the number of endophytic microorganisms during storage showed the same trend that was observed for epiphytic microorganisms. Analysis of the microbial quantity after transportation of green products showed an increase in abundance of the revealed groups of epiphytes and endophytes by 1.5–3 times upon absolute prevalence of bacteria. After short-term storage, a significant growth of the revealed microbial groups was found; with that, their quantity was 1.5–6.5 times higher at (4–5) C than at (0–1) C. The authors experimentally confirmed the conclusion that with respect to reduction of losses due to microbiological spoilage and extension of shelf life, the cold storage regime of the studied plant products at near-zero temperatures is preferable compared to the regimes of storage at higher positive temperatures

SOME ULTRASTRUCTURAL ASPECTS OF ENDOTHELIAL REACTIVITY

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Different phenotypic outcome due to site-specific phosphorylation in the cancer-associated NQO1 enzyme studied by phosphomimetic mutations

Protein phosphorylation is a common phenomenon in human flavoproteins although the functional consequences of this site-specific modification are largely unknown. Here, we evaluated the effects of site-specific phosphorylation (using phosphomimetic mutations at sites S40, S82 and T128) on multiple functional aspects as well as in the structural stability of the antioxidant and disease-associated human flavoprotein NQO1 using biophysical and biochemical methods. In vitro biophysical studies revealed effects of phosphorylation at different sites such as decreased binding affinity for FAD and structural stability of its binding site (S82), conformational stability (S40 and S82) and reduced catalytic efficiency and functional cooperativity (T128). Local stability measurements by H/D exchange in different ligation states provided structural insight into these effects. Transfection of eukaryotic cells showed that phosphorylation at sites S40 and S82 may reduce steady-levels of NQO1 protein by enhanced proteasome-induced degradation. We show that site-specific phosphorylation of human NQO1 may cause pleiotropic and counterintuitive effects on this multifunctional protein with potential implications for its relationships with human disease. Our approach allows to establish relationships between site-specific phosphorylation, functional and structural stability effects in vitro and inside cells paving the way for more detailed analyses of phosphorylation at the flavoproteome scale

Allosteric Communication in the Multifunctional and Redox NQO1 Protein Studied by Cavity-Making Mutations

Allosterism is a common phenomenon in protein biochemistry that allows rapid regulation of protein stability; dynamics and function. However, the mechanisms by which allosterism occurs (by mutations or post-translational modifications (PTMs)) may be complex, particularly due to long-range propagation of the perturbation across protein structures. In this work, we have investigated allosteric communication in the multifunctional, cancer-related and antioxidant protein NQO1 by mutating several fully buried leucine residues (L7, L10 and L30) to smaller residues (V, A and G) at sites in the N-terminal domain. In almost all cases, mutated residues were not close to the FAD or the active site. Mutations L\u2192G strongly compromised conformational stability and solubility, and L30A and L30V also notably decreased solubility. The mutation L10A, closer to the FAD binding site, severely decreased FAD binding affinity ( 4820 fold vs. WT) through long-range and context-dependent effects. Using a combination of experimental and computational analyses, we show that most of the effects are found in the apo state of the protein, in contrast to other common polymorphisms and PTMs previously characterized in NQO1. The integrated study presented here is a first step towards a detailed structural-functional mapping of the mutational landscape of NQO1, a multifunctional and redox signaling protein of high biomedical relevance