Here we present a demonstration of the proof of principle that absolute concentration of a protein within a mixture of other proteins can be measured with SI traceability. The method used was based on tryptic digestion of a protein followed by quantification using double exact matching isotope dilution mass spectrometry (IDMS) of the peptides released. To provide full SI traceability to measurements of protein concentration we demonstrated a method of SI traceable peptide quantification in which the peptide standards used were quantified by an amino acid analysis method that incorporated double exact matching IDMS and amino acid standards of known purity. The concentration of the protein was therefore determined based upon the concentration of tryptic peptides, which in turn had been quantified based upon amino acid standards. This allowed fully SI-traceable measurements of protein concentration to be made. Important caveats in the implementation of this approach are also discussed and examples of how these can have detrimental effects on the measurements are shown.
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http://dx.doi.org/10.1016/j.ab.2008.02.010 | DOI Listing |
Plant Cell Environ
January 2025
College of Resources and Environmental Sciences, Department of Plant Nutrition, China Agricultural University, Beijing, Haidian, China.
The occurrence of external L-glutamate at the Arabidopsis root tip triggers major changes in root architecture, but the mechanism of -L-Glu sensing is unknown. Members of the family of GLUTAMATE RECEPTOR-LIKE (GLR) proteins are known to act as amino acid-gated Ca-permeable channels and to have signalling roles in diverse plant processes. To investigate the possible role of GLRs in the root architectural response to L-Glu, we screened a collection of mutants with T-DNA insertions in each of the 20 AtGLR genes.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Shanghai Jiao Tong University, Chemistry, 800 Dongchuan Road, Minhang, 200240, Shanghai, CHINA.
Hydrogen sulfide (H2S) plays crucial inflammatory modulating roles, representing a promising candidate for anti-inflammatory therapies. However, current H2S delivery approaches lack sufficient specificity against inflammatory response. Herein, regarding the overexpressed aminopeptidase N (APN) at the inflammation sites, an APN-activated self-immolative carbonyl sulfide (COS)/H2S donor (AlaCOS) was developed for inflammatory response-specific H2S delivery.
View Article and Find Full Text PDFOrg Lett
January 2025
Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, China.
Here, we present a three-component successive radical addition strategy for the preparation of complex noncanonical α-amino acids from easily available glycine derivatives, alkenes, and aryl sulfonium salts via a copper-catalyzed photoredox-neutral catalytic cycle. The utility of this method is further demonstrated by its application in late-stage site-selective modifications of glycine residues in short peptides. It is worth noting that only 1 mol % copper catalyst is required in this reaction, demonstrating high catalytic efficiency.
View Article and Find Full Text PDFNatl Sci Rev
January 2025
Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai 200031, China.
Defining metabolic health is critical for the earlier reversing of metabolic dysfunction and disease, and fasting-based diagnosis may not adequately assess an individual's metabolic adaptivity under stress. We constructed a novel Health State Map (HSM) comprising a Health Phenotype Score (HPS) with fasting features alone and a Homeostatic Resilience Score (HRS) with five time-point features only ( = 30, 60, 90, 180, 240 min) following a standardized mixed macronutrient tolerance test (MMTT). Among 111 Chinese adults, when the same set of fasting and post-MMTT data as for the HSM was used, the mixed-score was highly correlated with the HPS.
View Article and Find Full Text PDFTheranostics
January 2025
Department of Pharmacology, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea.
Adenovirus-based therapies have encountered significant challenges due to host immunity, particularly from pre-existing antibodies. Many trials have struggled to evade antibody response; however, the efficiency of these efforts was limited by the diversity of antibody Fv-region recognizing multiple amino acid sequences. In this study, we developed an antibody-evading adenovirus vector by encoding a plasma-rich protein transferrin-binding domain.
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