Metabolism of Imidazole by a Pseudomonad

Intermediates formed during the microbial degradation of imidazole, namely 4(5)-imidazolone, formiminoglycine, and possibly glycine, are similar to those formed during metabolism of imidazole derivatives.     

Yeast alcohol dehydrogenase immobilized in a glutaraldehyde–albumin matrix: Kinetics and cofactor diffusional effects*

This study was carried out to define how the overall rate of reaction would be influenced by different degrees of diffusional resistance to cofactor transport within an oxidoreductase membrane matrix. To accomplish this, 0.7–6.6μM yeast alcohol dehydrogenase was immobilized in an albumin matrix crosslinked with 2.5 or 5.0% glutaraldehyde to give 102–1685 μM thick membranes. The enzyme half-life was at least doubled at pH 7.5 or 8.8 on immobilization. Values of the kinetic constants for the soluble and immobilized enzyme were determined at 25°C and pH 8.8 over the range of 0.01–1.0M bulk solution concentration of ethanol as substrate and 140–1000μM bulk solution concentration of nicotinamide adenine dinucleotide (NAD⁺) as cofactor, to give essentially single substrate kinetics in NAD⁺. Equilibrium partitioning of ethanol and NAD⁺ between the solution and membrane was measured and used in the data analysis. The four kinetic constants for the soluble enzyme agreed with literature values; and all increased with immobilization of the enzyme. The Michaelis constants for NAD⁺ and for ethanol were greater for the immobilized enzyme. The diffusional resistance to NAD⁺ transport, presented in terms of the Thiele modulus, showed that the overall rate of reaction was decreased by about 50% even at values of the modulus as low as 2.0.     

Bioelectrochemical fuel cells

In the past 20 years, inorganic fuel cells have been transformed from novelty devices to practical energy transfer-energy storage units. However, the advantage of the high operating efficiency afforded by these fuel cells is partially offset by (a) the limited viability and high cost of the catalysts, (b) the highly corrosive electrolytes, and (c) the elevated operating temperatures. The possibility exists to reduce some of these problems through the development of bioelectrochemical fuel cells. Such biological/electrochemical systems incorporate either microorganisms or enzymes as an active component within the specified electrode compartments. Recent studies with microorganisms as part of the anode compartment have been aimed at defining the mechanism of the observed electrochemical reactions. Recent investigations on the use of cell-free enzyme preparations in the electrode compartments have dealt primarily with developing methodology and defining mechanisms for enhancing the rate of electron transfer from the enzyme-cofactor active site to the solid electrode surface. Applications of this developing technology have been envisioned for analytical chemistry, medical devices, energy transfer, electrochemical synthesis, and detoxification. In this review, the theory and problems of bioelectrochemical fuel cells are described and related to research, both recent and proposed, for the practical development of this area.     

Metabolipidomic profiling reveals an age‐related deficiency of skeletal muscle pro‐resolving mediators that contributes to maladaptive tissue remodeling

Specialized pro‐resolving mediators actively limit inflammation and support tissue regeneration, but their role in age‐related muscle dysfunction has not been explored. We profiled the mediator lipidome of aging muscle via liquid chromatography‐tandem mass spectrometry and tested whether treatment with the pro‐resolving mediator resolvin D1 (RvD1) could rejuvenate the regenerative ability of aged muscle. Aged mice displayed chronic muscle inflammation and this was associated with a basal deficiency of pro‐resolving mediators 8‐oxo‐RvD1, resolvin E3, and maresin 1, as well as many anti‐inflammatory cytochrome P450‐derived lipid epoxides. Following muscle injury, young and aged mice produced similar amounts of most pro‐inflammatory eicosanoid metabolites of cyclooxygenase (e.g., prostaglandin E₂) and 12‐lipoxygenase (e.g., 12‐hydroxy‐eicosatetraenoic acid), but aged mice produced fewer markers of pro‐resolving mediators including the lipoxins (15‐hydroxy‐eicosatetraenoic acid), D‐resolvins/protectins (17‐hydroxy‐docosahexaenoic acid), E‐resolvins (18‐hydroxy‐eicosapentaenoic acid), and maresins (14‐hydroxy‐docosahexaenoic acid). Similar absences of downstream pro‐resolving mediators including lipoxin A₄, resolvin D6, protectin D1/DX, and maresin 1 in aged muscle were associated with greater inflammation, impaired myofiber regeneration, and delayed recovery of strength. Daily intraperitoneal injection of RvD1 had minimal impact on intramuscular leukocyte infiltration and myofiber regeneration but suppressed inflammatory cytokine expression, limited fibrosis, and improved recovery of muscle function. We conclude that aging results in deficient local biosynthesis of specialized pro‐resolving mediators in muscle and that immunoresolvents may be attractive novel therapeutics for the treatment of muscular injuries and associated pain in the elderly, due to positive effects on recovery of muscle function without the negative side effects on tissue regeneration of non‐steroidal anti‐inflammatory drugs.     

Effects of Stress Modifier Biostimulants on Vegetative Growth,Nutrients, and Antioxidants Contents of Garden Thyme (Thymus vulgaris L.) Under Water Deficit Conditions

The aim of this study is to investigate the effect of stress modulators on vegetative growth, antioxidants, and nutrient content of Thymus vulgaris L. under water deficit stress conditions. A factorial experiment was performed in the form of a randomized complete block design with 10 treatments and 3 replications in the 2019–2020 growing season. The factors were stress modulators at 5 levels (ZN: zinc nano-fertilizer, AA: amino acid, SW: seaweed, HA: humic acid and C: control) and irrigation regime at 2 levels [FIrr: full irrigation (100% field capacity) and DIrr: deficit irrigation (50% field capacity)]. The highest plant height, number of branches, and total dry weight of the garden thyme plant were observed in the foliar application of HA and SW under full irrigation conditions. Relative water content, chlorophyll a and b, and uptake of nutrients (N, P, and K) were reduced under water deficit stress, but the foliar application of stress modulators increased relative water content, chlorophyll content, and nutrient uptake of the garden thyme plant significantly compared with control. The water deficit increased proline content, total flavonoid, and phenol content in the garden thyme plant. So, the highest total flavonoid and phenol content was obtained from plants treated with HA, whereas proline content was higher in the control plants. Soluble sugars and essential oil increased significantly under water deficit stress conditions. The foliar application of HA compared to the control plant increased soluble sugars and essential oil in garden thymes. The activities of catalase, superoxide dismutase, and ascorbate peroxidase enzymes were improved in stress modulator treatments such as HA and SW compared to control plants under water deficit stress conditions. The plants of garden thymes showed a good response to stress modulator treatments under water stress conditions, and HA and SW treatments were found to be more effective.

     

Effect of nucleoside 5′-di- and 5′-tri-phosphates on pancreatic ribonuclease activity

1. ADP, ATP and GDP inhibited the phosphotransferase activity, the release of cyclic nucleotides from RNA, of ribonuclease. No significant inhibition was elicited by pyrimidine 5'-nucleoside diphosphates, CDP and UDP. 2. Inhibition by ADP, AMP, adenosine, adenine, NAD and NADP was insignificant at the concentrations tested. Small inhibition was observed with high concentrations of AMP and only when soluble RNA was the substrate. 3. Inhibition by ADP was found to be ;uncompetitive'. 4. Results seem to indicate that at least for optimum inhibition the polyphosphate of the purine nucleoside is essential. They further suggest that the inhibitor acts by combining with the enzyme only when the enzyme is bound to the substrate.     

p-Benzoquinone activation of metal oxide electrodes for attachment of enzymes

The mechanisms by which p-benzoquinone brings about the activation of a metal oxide surface and subsequent coupling of an enzyme has been investigated. Indium-tin oxide (ITO)coated glass plates were derivatized with an aminosilane and then activated with p-benzoquinone. Differential pulse voltammetry was used to distinguish between mono- and disubstitution of the benzoquinone, both for a model system in homogeneous solution and for the aminosilane derivatized plates. Glucose oxidase was attached covalently to the benzoquinone-aminosilane activated ITO plates to give an enzymatically active electrode.     

Salinity Stress in Wheat: Effects,Mechanisms and Management Strategies

Salinity stress is a major threat to global food production and its intensity is continuously increasing because of anthropogenic activities. Wheat is a staple food and a source of carbohydrates and calories for the majority of people across the globe. However, wheat productivity is adversely affected by salt stress, which is associated with a reduction in germination, growth, altered reproductive behavior and enzymatic activity, disrupted photosynthesis, hormonal imbalance, oxidative stress, and yield reductions. Thus, a better understanding of wheat (plant) behavior to salinity stress has essential implications to devise counter and alleviation measures to cope with salt stress. Different approaches including the selection of suitable cultivars, conventional breeding, and molecular techniques can be used for facing salt stress tolerance. However, these techniques are tedious, costly, and labor-intensive. Management practices are still helpful to improve the wheat performance under salinity stress. Use of arbuscular mycorrhizal fungi, plant growth-promoting rhizobacteria, and exogenous application of phytohormones, seed priming, and nutrient management are important tools to improve wheat performance under salinity stress. In this paper, we discussed the effect of salinity stress on the wheat crop, possible mechanisms to deal with salinity stress, and management options to improve wheat performance under salinity conditions.     

Isolation, Identification, and Characterization of a Lipoate-Degrading Pseudomonad and of a Lipoate Catabolite

A strain of bacteria that can degrade lipoic acid was isolated from soil. The bacterium, adapted to use 0.4% dl-lipoate as the sole organic substrate to supply carbon, sulfur, and energy, was identified morphologically and physiologically as a strain of Pseudomonas putida. Degradation of 1,6-(14)C-lipoic acid, synthesized from 1,6-(14)C-adipic acid, was evidenced by: (i) loss of approximately 50% of the total radioactivity from the medium after bacterial growth; (ii) appearance of (14)C-degradation products upon paper and thin-layer chromatography of the culture medium; and (iii) oxygraphically measured utilization of O(2) by cells in the presence of lipoate or other oxidizable substrates. Analyses of the benzene extract of culture medium by infrared, nuclear magnetic resonance, and mass spectrometry, and by gas-liquid chromatography after desulfuration, have characterized bisnorlipoic acid, or 4,6-dithiohexanoic acid, as the major catabolite present in the medium. beta-Oxidation of the side chain is thus proven to be a pathway employed by the pseudomonad to degrade lipoic acid.