Investigation of liver alcohol dehydrogenase catalysis using an NADH biomimetic and comparison with a synthetic zinc model complex

We have compared the catalytic activity of horse liver alcohol dehydrogenase (LADH) with a synthetic zinc model complex in the presence of N-benzyl-1,4-dihydronicotinamide (BNAH), a cofactor which serves as a biomimetic for the natural cofactor NADH. We have used five different substrates (benzaldehyde, p-anisaldehyde, 4-nitrobenzaldehyde, 2-pyridine carboxaldehyde, and 5-pyrimidine carboxaldehyde) in this study. These substrates vary in their substituent inductive effect, which is the ability to donate or withdraw electron density away from their carbonyl-functional group. Our results reveal that in the presence of NADH, geometric factors (induced fit of the substrate and cofactor in the enzyme active site) are vital. However, reactivity assays show that in the presence of BNAH, there is a strong correlation between substrate electronic environment and the observed catalytic rate, i.e. the more electron withdrawn the substrate, the greater the speed at which the reduction reaction occurs. NMR spectroscopy reveals that a synthetic zinc model complex catalyzes the reduction of substrates in a manner consistent with LADH enzyme

Contributions of active site residues to substrate binding and catalysis of 5-nitroanthranilic acid aminohydrolase

Synthetic and naturally occurring nitroaromatic compounds are recalcitrant to degradation and they are toxic/mutagenic. The symbiont Bradyrhizobium sp. JS329 is the first microbe found to degrade a biological nitroaromatic compound, 5-nitroanthralinic acid (5NAA), which is secreted by the bacterium responsible for potato scabs, Streptomyces scabies. The first enzyme in the degradation pathway is 5NAA-aminohydrolase (5NAA-A), a metalloprotease family member that has evolved to hydrolyze 5NAA to 5-nitrosalicylic acid. 5NAA-A is the first characterized metalloenzyme to utilize nucleophilic aromatic substitution. Here, I used isothermal titration calorimetry, enzyme activity assays, and X-ray crystallography to dissect contributions of individual active site and second-shell residues for assisting substrate transport. My studies demonstrate the interplay between substrate binding and catalysis requirements for this unusual metalloenzyme. Knowledge of the 5NAA-A structure and mechanism informs potential bioremediation and biocatalytic approaches to mitigate the environmental and ecological impact of nitroaromatic and other challenging substrates.M.S

In vitro Interactions between RNA and Ruthenium/Ferrocene Metal Complexes

RuL2 is a potentially new inorganic anti-cancer drug that contains both Ruthenium (III) & Iron (II) metal centers. The synergistic action of the two metal centers has the potential to combine the therapeutic effects of current drugs, Cisplatin and NAMI-A, and could potentially increase the overall efficacy of the drug. Previous work on RuL2 has demonstrated that it interacts with DNA and RNA, suggesting that it may share similar molecular targets as Cisplatin. RNA has emerged as our molecular target for metal therapeutics not only due to its chemical similarity with DNA, but also due to its essential role in cellular function. My project centered on a main question: what is the binding strength of RuL2 to RNA? How does its binding strength compare to Cisplatin and NAMI-A? The in vitro binding affinity of Cisplatin, NAMI-A, and RuL2 complexes with RNA was investigated using DHFR enzyme activity assay, and electrophoretic mobility shift assay (EMSA). The in vitro translation studies using DHFR assay showed that all three complexes inhibited the enzymatic activity of DHFR in catalyzing dihydrofolic acid to tetrahydrofolic acid, as the concentrations of drugs were increasing. On the other hand, electrophoretic mobility shift assay (EMSA) studies using SRL RNA incubated with Cisplatin, NAMI-A, and RuL2 indicated a concentration-dependent tendency for the RNA sample to migrate in increasingly diffuse streaks. So we can conclude that Cisplatin, NAMI-A, and RuL2 are all interacting with RNA. The accurate binding location and ration of each drug to RNA can be further investigated by running reverse transcriptase and ICP-OES assays, respectively

Correlation between Different Types and Intensities of Physical Activity and Children’s Sports Performance

This study used the literature method to systematically review correlation studies on the sports performance of school-aged children aged 7–12 years. Twenty related studies were summarized and sorted out. The results showed that most of the studies used the motion sensor method to measure the intensity of physical activity, and few used the observation and survey methods. Most studies measured sports performance on the basis of changes in various physical fitness indicators to reflect differences in sports performance. Moderate- and high-intensity comprehensive sports were beneficial in improving the sports performance of school-aged children. At present, differences in the positive effects of various physical activities on children’s sports performance need to be further compared. The research results can provide theoretical scientific guidance for the selection of children’s physical activities and sports methods and the development of comprehensive courses such as school sports activities, as well as help children’s sports performance improvement and effective development of physical and mental health

Emission characteristics of kerosene-air spray combustion with plasma assistance

A plasma assisted combustion system for combustion of kerosene-air mixtures was developed to study emission levels of O2, CO2, CO, and NOx. The emission measurement was conducted by Testo 350-Pro Flue Gas Analyzer. The effect of duty ratio, feedstock gas flow rate and applied voltage on emission performance has been analyzed. The results show that O2 and CO emissions reduce with an increase of applied voltage, while CO2 and NOx emissions increase. Besides, when duty ratio or feedstock gas flow rate decreases, the same emission results would appear. The emission spectrum of the air plasma of plasma assisted combustion actuator was also registered to analyze the kinetic enhancement effect of plasma, and the generation of ozone was believed to be the main factor that plasma makes a difference in our experiment. These results are valuable for the future optimization of kerosene-fueled aircraft engine when using plasma assisted combustion devices to exert emission control

Hepatic Transcriptome Analysis Provides New Insight into the Lipid-Reducing Effect of Dietary Taurine in High–Fat Fed Groupers (Epinephelus coioides)

A transcriptome analysis was conducted to provide the first detailed overview of dietary taurine intervention on liver lipid accumulation caused by high–fat in groupers. After an eight-week feeding, the fish fed 15% fat diet (High–fat diet) had higher liver lipid contents vs. fish fed 10% fat diet (Control diet). 15% fat diet with 1% taurine (Taurine diet) improved weight gain and feed utilization, and decreased hepatosomatic index and liver lipid contents vs. the High–fat diet. In the comparison of the Control vs. High–fat groups, a total of 160 differentially expressed genes (DEGs) were identified, of which up- and down-regulated genes were 72 and 88, respectively. There were 49 identified DEGs with 26 and 23 of up- and down-regulated in the comparison to High–fat vs. Taurine. Several key genes, such as cysteine dioxygenase (CDO1), ADP–ribosylation factor 1/2 (ARF1_2), sodium/potassium–transporting ATPase subunit alpha (ATP1A), carnitine/acylcarnitine translocase (CACT), and calcium/calmodulin–dependent protein kinase II (CAMK) were obtained by enrichment for the above DEGs. These genes were enriched in taurine and hypotaurine metabolism, bile secretion, insulin secretion, phospholipase D signaling pathway, and thermogenesis pathways, respectively. The present study will also provide a new insight into the nutritional physiological function of taurine in farmed fish

Digestion Performance and Microbial Metabolic Mechanism in Thermophilic and Mesophilic Anaerobic Digesters Exposed to Elevated Loadings of Organic Fraction of Municipal Solid Waste

Mesophilic and thermophilic anaerobic digestion reactors (MR and TR) for the organic fraction of municipal solid waste (OFMSW) were tested to reveal the differential microbial responses to increasing organic loading rate (OLR). MR exhibited faster adaptation and better performance at an OLR range of 1.0–2.5 g VS·L−1·d−1, with average profiles of a biogas yield of 0.38 L/gVSadded*d at 0.5 g/L*d OLR and 0.69 L/gVSadded*d at 2.5 g/L*d OLR, whereas TR had a biogas yield of 0.07 L/gVSadded*d at 0.5 g/L*d OLR and 0.44 L/gVSadded*d at 2.5 g/L*d OLR. The pyrosequencing results of amplicons revealed the microbial mechanisms of OFMSW anaerobic digestion. Larger shifts in the bacteria composition were observed in the TR with OLR elevation. For methanogens in both reactors, Methanothrix dominated in the MR while Methanosarcina was favored in the TR. Moreover, analysis of the mode and efficiency of metabolism between the MR and TR demonstrated different performances with more efficiency related to the limiting hydrolytic acid step