Barley malt is essential for beer production. In the present study, the nonprolamin fractions including proteins with structural functions or metabolic activities were extracted from barley malts of the widely used cultivars Gangpi and Baudin in China. The metabolic proteomes (pI 4-7) were constructed and compared using two-dimensional electrophoresis (2DE) followed by matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry (MALDI-TOF/TOF) identification. There were 333 and 354 spots detected in the 2DE gels of Gangpi and Baudin malts, respectively, and about 90% of these spots were shared by the two malts. For all, 377 were successfully identified to 192 proteins, most of which were enzymes and enzyme inhibitors, suggesting important roles in barley malting and the mashing stage of brewing. The Baudin malt was found to contain more spots representing amylases, pathogen-related proteins, and chaperones than the Gangpi malt. In addition, enzymes involved in glycolysis and redox pathways showed significantly different profiles between the two malts, permitting a more in-depth elucidation of the relationship between differential proteins and malt qualities.
Mycoplasma bovis(Mb) is one of the major pathogens which can induce pneumonia,arthritis,mastitis and otitis media in cattle.Diseases caused by Mycoplasma bovis have caused huge economic losses and widely spread in Europe as well as America.It is reported that Mb was first isolated from pneumonia of cattle in 2008 in our country,so at present,due to lack understanding of Mb,this article briefly overview on biological properties and membrane proteins of Mb,with a view to provide a frame of reference for prevention and treatment of diseases caused by Mycoplasma bovis in our country.
This study presents the development and validation of a fast and high throughput method based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique followed by gas chromatography quadrupole time-of-flight mass spectrometry (GC-QTOF/MS) for the simultaneous determination of 21 organophosphorus flame retardants (OPFRs) in rice samples. The factors that impact sample pretreatment and GC-QTOF/MS were optimized and isotope dilution mass spectrometry (IDMS) was established for accurate quantification. The recoveries of OPFRs were in the ranges of 82.3%-110.4% and the relative expanded uncertainties ranged from 1.52% to 11.98%. The limit of quantification (LOQ) ranged from 0.05 ng/g to 1.07 ng/g, which is lower than or comparable to that reported in previous works. The developed method was successfully applied to the analysis of real rice samples and 14 OPFRs were detected, with contents ranging from 0.05 ng/g to 10.43 ng/g.
In this study, we investigated the effects of ohmic heating (OH) on the structural properties and allergenicity of parvalbumin (PV). High purity PV was obtained from eel meat via salting, dialysis and column chromatography. Western boltting, ELISA, the simulated gastric fluid (SGF) assay, and the simulated intestinal fluid (SIF) assay, showed that the digestive stability of PV improved to some extent with an increase in OH time. The time and energy required for OH significantly decreased compared to other heating methods (water bath heating (WH), OH combined with WH, and OH combined with air thermostatic heating (AH)). SDS-PAGE and tricine-SDS-PAGE analyses showed that the molecular weight of PV was approximately 12 kDa and that the molecular weight of PV did not change, however the protein bands became shallower with prolonged OH time. The amino acid content, secondary structure, microstructure and dielectric properties of PV changed significantly with prolonged OH exposure.
Main text The CCQM-K154.b comparison was coordinated by the Bureau International des Poids et Mesures (BIPM) and the Chinese National Institute of Metrology (NIM) on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA) and/or have participated in the BIPM's Mycotoxin Metrology Capacity Building and Knowledge Transfer (MMCBKT) project as part of its "Metrology for Safe Food and Feed in Developing Economies" Capacity Building Programme. Gravimetrically-prepared solutions having an assigned mass fraction of specified organic analytes are routinely used to calibrate measurement processes for the quantification of the same analytes in matrix samples. Appropriate assignments of the property value and associated uncertainty of calibration solutions thus underpin the traceability of routine analysis and are critical for accurate measurements. Evidence of successful participation in relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes and designated institutes. In total, eleven NMIs/DIs participated in the Track C, Model II, Key Comparison CCQM-K154.b [Gravimetric preparation and value assignment of aflatoxin B1 (AfB1) in acetonitrile (ACN)] for emerging areas of global interest and innovation. Participants were requested to gravimetrically prepare calibration solutions and value assign the mass fractions, expressed in mg/kg, of aflatoxin B1 (AfB1) in the acetonitrile (ACN) solution. Study samples, with assigned values and associated uncertainties were prepared by the comparison participants and sent to the coordinating laboratory for comparison. The Key Comparison Reference Values (KCRVs), calculated form values measured by the coordinating laboratory based on calibrations obtained from independent gravimetrically prepared calibrant solutions, agreed with participants reported values, within their stated uncertainties. AfB1 was selected to be representative of polar aflatoxins. Aflatoxins are a class of mycotoxins generally produced by fungi of the genus Aspergillus. It was anticipated to provide a challenge representative for the gravimetrical preparation and value assignment of calibration solutions in the mass fraction range of 2 mg/kg to 50 mg/kg of mycotoxins with broadly similar structural characteristics. Nine participants of the MMCBKT programme were provided with a stock solution having a known AfB1 mass fraction and expanded uncertainty to use to gravimetrically prepare and value assign a calibration solution. Three NMIs/DIs also participated using their own calibration solutions. The use of in-house solutions required an additional capacity to undertake a fit-for-purpose purity assessment. NIM was the only NMI participating using both the MMCBKT based and their own in-house assigned solutions in order to connect the two different groups. It was decided to propose separate KCRVs for each of the two ampoules provided by the participating NMIs/DIs based on the AfB1 mass fraction. This allowed participants to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibration solutions and to assess the AfB1 mass fraction. The majority of the AfB1 mass fraction KCRVs (wKCRV) for CCQM-K154.b spanned a mass fraction range of 2.02 mg/kg to 31.57 mg/kg. The relative expanded uncertainties U(wKCRV) ranged from 0.69 % to 2.93 %. Inspection of the degree of equivalence plots for the AfB1 mass fraction assignments in CCQM-K154.b indicated that there was an excellent agreement of results. Solely, the AfB1 mass fraction assignments of INRAP did not agree with the KCRVs. It was found that the samples were altered as a result of an acid contamination. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Abstract The synthetic pathway for Etiracetam depends on alpha‐ethyl‐2‐oxo‐1‐pyrrolidineacetic acid (AEOPA) as a crucial intermediate. This paper presents an enzymatic synthesis approach for producing ( R )‐AEOPA. Through database mining, we discovered a tauriopine dehydrogenase capable of catalyzing the reaction between γ‐aminobutyric acid and 2‐oxobutyric acid, resulting in the synthesis of ( R )‐4‐(carboxypropylamino) butyric acid with a specific activity of 6.74 U/mg. By enhancing substrate affinity and catalytic efficiency of Cg TaDH through protein engineering, we achieved a 5.9‐fold increase in enzyme activity compared to the wild type. Further optimization led to a space‐time yield (STY) of 3.95 g/L/h for ( R )‐4‐(carboxypropyl amino) butyric acid and a high yield of 73.0 % for the final product, ( R )‐AEOPA. This study demonstrates a novel synthesis method for ( R )‐AEOPA and highlights the potential of biocatalysis in improving the production of Etiracetam through successful enzymatic processes.
The combined effects of succinic anhydride (SA) succinylation and linear dextrin (LD) glycation on whey protein hydrolysates (WPH) and their stabilized emulsions were evaluated. Degree of succinylation (DS), degree of glycation (DG), and degree of browning of samples suggested that a competitive displacement of reactive groups existed when WPH reacted with SA and LD in different orders. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and far-UV circular dichroism (CD) indicated that the order of modification methods had a significant effect on secondary structures of WPH. Succinylation combined with glycation effectively reduced the surface hydrophobicity and increased the molecular flexibility of WPH. Meanwhile, the total free -SH content decreased, and the exposed free -SH content increased. Results of storage stability and gastrointestinal fate of the curcumin-loaded emulsion revealed that the modified WPH with higher DS was more effective for improving the curcumin bioaccessibility, while that with higher DG was more effective for enhancing the stability of the emulsion.
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