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关键词： Acid phosphatase activity   Contamination   Dehydrogenase activity   Kunai grass biochar   Soil respiration rate  

摘要： Waste disposal, metal plating, refineries, and mining operations frequently contaminate soils with nickel (Ni). We explored the effects of artificial Ni contamination (0, 56, and 180 mg Ni kg(-1)) on the soil biochemical indices. The lab experiment also investigated the possible use of kunai grass (Imperata cylindrica) biochar at a 0.75% dry weight basis to alleviate contamination effects. The biochemical indices such as dehydrogenase enzyme activity, acid phosphatase enzyme activity, and soil respiration rates were monitored in three replications. High level of Ni (180 mg kg(-1)) suppressed soil respiration rate by 37% and dehydrogenase activity by 62% up to 15 days. The acid phosphatase activity was not affected by Ni levels and was insensitive to Ni contamination. Biochar application to the Ni contaminated soil did not improve the soil's key biological properties. The beneficial effects of biochar could be limited to improvements in soil chemical properties and not on index biological properties.

关键词： Biotin   Biotin protein ligase   Fungal pathogens   Saccharomyces cerevisiae   Botrytis cinerea   Zymoseptoria tritici  

摘要： Biotin protein ligase (BPL) is an essential enzyme in all kingdoms of life, making it a potential target for novel anti-infective agents. Whilst bacteria and archaea have simple BPL structures (class I and II), the homologues from certain eukaryotes such as mammals, insects and yeast (class III) have evolved a more complex structure with a large extension on the N-terminus of the protein in addition to the conserved catalytic domain. The absence of atomic resolution structures of any class III BPL hinders structural and functional analysis of these enzymes. Here, two new class III BPLs from agriculturally important moulds Botrytis cinerea and Zymoseptoria tritici were characterised alongside the homologue from the prototypical yeast Saccharomyces cerevisiae. Circular dichroism and ion mobility-mass spectrometry analysis revealed conservation of the overall tertiary and sec-ondary structures of all three BPLs, corresponding with the high sequence similarity. Subtle structural differ-ences were implied by the different thermal stabilities of the enzymes and their varied Michaelis constants for their interactions with ligands biotin, MgATP, and biotin-accepting substrates from different species. The three BPLs displayed different preferences for fungal versus bacterial protein substrates, providing further evidence that class III BPLs have a 'substrate validation' activity for selecting only appropriate proteins for biotinylation. Selective, potent inhibition of these three BPLs was demonstrated despite sequence and structural homology. This highlights the potential for targeting BPL for novel, selective antifungal therapies against B. cinerea, Z. tritici and other fungal species.

关键词： Bialaphos   2-Phosphinomethylmalate synthase   DRE-TIM metallolyase Superfamily   Enzyme function   Sequence similarity network  

摘要： 2-Phosphinomethylmalate synthase (PMMS) from Streptomyces hygroscopicus catalyzes the first step in the biosynthesis of the herbicide bialophos using 3-phosphinopyruvic acid and acetyl coenzyme A as substrates to form 2-phosphinomethylmalic acid and coenzyme A. PMMS belongs to the Claisen condensation-like (CC-like) subgroup of the DRE-TIM metallolyase superfamily, which uses conserved active site architecture to catalyze a functionally-diverse set of reactions. Analysis of a sequence similarity network for the CC-like subgroup identified PMMS and the related R-citrate synthase in an early-diverging cluster suggesting that this group of sequences are more distinct in relation to other Claisen-condensation subgroup members. To better understand the structure/function landscape of the CC-like subgroup PMMS was recombinantly expressed in Escherichia coli, purified, and characterized with respect to its enzymatic properties. Using oxaloacetate as a substrate analog, the recombinantly-produced enzyme exhibited improved Michaelis constants relative to the previously reported natively-produced enzyme. Results from pH rate profiles and kinetic isotope effects were consistent with results from other members of the CC-like subgroup supporting acid-base chemistry and hydrolysis of the direct Claisencondensation product as the rate-determining step. Results of site-directed mutagenesis experiments indicate that PMMS uses an active-site architecture similar to homocitrate synthase to select for a dicarboxylic acid substrate.

关键词： Clams   Metal contamination   Safety consumption   Seasons   Biochemical performance  

摘要： Shellfish farming and shellfish harvesting have been practiced for a long time in the Ria de Aveiro coastal lagoon (Portugal). Among commercial bivalves, Manila clam Ruditapes phillippinarum represents one of the most important species inhabiting this coastal system. Introduced in Portugal in 1984, naturalised R. philippinarum clam populations have been subjected to several pressures that may threaten this resource sustainable management: illegal fishing, harvesting in chemically polluted sites with impacts on human health and lack of control in terms of productivity with the risk of a progressive decline of the biomass. On behalf of the ASARISAFE project (with the title Safety and sustainable management of valuable clam product in Portugal and China) the environmental quality of Manila clam harvesting sites was evaluated, focusing on inorganic pollution and health status of clams in terms of bioaccumulation as well as biochemical performance. Seasonal sampling campaigns were conducted in six R. philippinarum harvesting areas evaluating inorganic pollution levels, in clam's tissues, sediment and water. Clams biochemical performance in terms of metabolism, energy reserves and oxidative stress was also assessed. The results obtained showed that mercury (Hg) and arsenic (As) were the elements with the highest BAF (Bioaccumulation factor) values, but contamination levels in tissues and sediments varied among sampling areas and seasonal campaigns. The amount of clams consumed per week to exceed Provisional Tolerable Week Intake (PTWI, kg) was the lowest for As, revealing that less 0.05 kg of clams was enough to exceed PTWI. However, the results obtained further demonstrated that the clam's biochemical performance was not responding to tissues contamination levels but were closely related to seasons, with distinct metabolic capacity and oxidative stress levels among distinct sampling periods during the year.

关键词： bioanalytical chemistry   CRISPR   electrochemistry   genetic circuits   primer exchange reaction  

摘要： A heterogeneous multi‐function biochemical circuit that can identify, transform, translate, and amplify biological signals into physicochemical signals was constructed and integrated into an electrochemistry‐based sensing platform for genetic analysis. Details of this research are described by Y. Dai, A. I. Caplan, C. C. Liu, and co‐workers in their Research Article on page 20545.

关键词： bioanalytical chemistry   CRISPR   electrochemistry   genetic circuits   primer exchange reaction  

摘要： Ein heterogener multifunktioneller Schaltkreis, der biologische Signale identifizieren, verstärken und in physikochemische Signale übersetzen kann, wurde in eine elektrochemische Sensorplattform für die Genanalyse integriert. Einzelheiten dieser Forschung werden im Forschungsartikel von Y. Dai, A. I. Caplan, C. C. Liu et al. auf S. 20726 präsentiert.

关键词： Azides   Hydrocarbons   Antimicrobial agents   Ketones   Cells  

摘要： A pathogenic bacterium has its own mechanisms for not only pathogenic attack but also exogenous invasion defense, in which the bacterial cell wall is the front line of attack and defense. We developed a biochemical lanthanide-encoding approach to quantify the uncanonical d-amino acid (d-X) that was edited in a small proportion into the terminal acyl-d-Ala-d-X of nascent peptidoglycan UDP-MurNAc-pentapeptides in the bacterial cell wall. This approach overcomes the difficulties regarding quantification and accuracy issues encountered by the popular optical imaging and traditional high-performance liquid chromatography-based methods. Newly synthesized -d-Leu and -d-Met were used together with -d-Ala for their metabolic assembly and then bioorthogonally encoded by the correspondingly fabricated -DOTA-Gd, -DOTA-Eu, and -DOTA-Sm tags. This approach allows direct quantification of the d-X in situ in the cell wall using Gd, Eu, and Sm species-unspecific isotope dilution inductively coupled plasma mass spectrometry, avoiding any tedious and complex "cell-broken" pretreatment procedures that might induce racemization of the d-X. The obtained site-specific and accurate in situ information about the d-X enables quantitative monitoring of the bacterial response when meets vancomycin, showing that the amounts of -d-Leu and -d-Met assembled are more important after determining the structure- and composition-dependent bacterial antibiotic resistance mechanisms. In addition, we found that the combined use of vancomycin and d-Ala restores the efficacy of vancomycin and might be a wise and simple way to combat vancomycin intermediate-resistant .

关键词： METAL-organic frameworks   MATERIALS analysis   ENZYMES   NANOSTRUCTURED materials  

摘要： In recent years, there has been rapid growth of enzyme-mimicking catalytic nanomaterials (nanozymes). Compared with biological enzymes, nanozymes exhibit several superiorities, including robust activity, easy production, and low cost, which endow them with promising applications in biochemical analysis. As an emerging member of nanozymes, metal-organic framework (MOF) nanozymes are attracting growing attention because of their composition and structural characteristics. Rationally designing MOFs with enzyme-like catalytic ability is opening up a new avenue for biochemical detection. In this Feature Article, we summarize the latest developments of MOF nanozymes and their applications in biochemical sensing. First, the types of nanozymes derived from MOFs are categorized, and effective strategies to improve the weak activity inherent in MOF nanozymes are introduced. Then, the multi-functionalization of MOFs with enzyme mimic activity and other attractive properties is emphasized. After that, the typical applications of MOF nanozymes in the detection of various analytes are rigorously reviewed. Finally, the current challenges and some development directions in this field are discussed. It is believed that the versatile nature of MOFs will bring a bright future for MOF nanozymes in biochemical analysis.

关键词： 高职高专   生物化学   生物科学史   意义  

摘要： 作为高职高专院校药学及护理专业的重要基础性课程,生物化学是基于分子水平对生命现象化学本质进行研究的学科,涉及内容广泛、理论性强,教学过程中普遍存在学习积极性不高、课堂氛围沉闷等问题。将生物科学史教育引入生物化学课程教学一方面能够丰富课堂内容、活跃课堂气氛;另一方面能够增进学生对生物科学的认识与理解。