Chemoenzymatic Installation of Site-Specific Chemical Groups on DNA Enhances the Catalytic Activity.

Functional DNAs are valuable molecular tools in chemical biology and analytical chemistry but suffer from low activities due to their limited chemical functionalities. Here, we present a chemoenzymatic method for site-specific installation of diverse functional groups on DNA, and showcase the application of this method to enhance the catalytic activity of a DNA catalyst. Through chemoenzymatic introduction of distinct chemical groups, such as hydroxyl, carboxyl, and benzyl, at specific positions, we achieve significant enhancements in the catalytic activity of the RNA-cleaving deoxyribozyme 10-23. A single carboxyl modification results in a 100-fold increase, while dual modifications (carboxyl and benzyl) yield an approximately 700-fold increase in activity when an RNA cleavage reaction is catalyzed on a DNA-RNA chimeric substrate. The resulting dually modified DNA catalyst, CaBn, exhibits a kobs of 3.76 min-1 in the presence of 1 mM Mg2+ and can be employed for fluorescent imaging of intracellular magnesium ions. Molecular dynamics simulations reveal the superior capability of CaBn to recruit magnesium ions to metal-ion-binding site 2 and adopt a catalytically competent conformation. Our work provides a broadly accessible strategy for DNA functionalization with diverse chemical modifications, and CaBn offers a highly active DNA catalyst with immense potential in chemistry and biotechnology.

Protecting meat color: The interplay of betanin red and myoglobin through antioxidation and coloration.

Myoglobin (Mb) responsible for meat color is easily oxidized resulting in meat discoloration. Here, betanin red (BR), as a natural pigment and antioxidant, was chosen for enhancing redness and inhibiting oxidation. Multiple spectroscopies, isothermal titration calorimetry and molecular docking demonstrated that BR changed the microenvironment of heme group and amino acid residues of Mb, inhibited the oxidation of oxymyoglobin. The main interaction force was hydrogen bond and one variable binding site provided a continuous protective barrier to realize antioxidation. The combination of antioxidation with the inherent red color of BR offered dual color protection effect on processed beef with the addition amount of 0.2 % BR. BR treatment enhanced the redness by 25.59 âˆ¼ 53.24 % and the sensory acceptance by 4.89 âˆ¼ 14.24 %, and decreased the lipid oxidation by 0.58 âˆ¼ 15.92 %. This study paves a theoretical basis for the application of BR and its structural analogues in meat color protection and other quality improvement.

Terminal temperature dominates the gel quality of chicken meat paste: An emphasis on multiple heating-cooling regimes.

A survey of various heating strategies, including terminal temperature (70 and 90 °C), step heating (with or without holding at 50 °C for 10 min) and step cooling (with or without holding at 50 °C for 10 min), on the gelation properties of chicken meat paste was conducted. Compared to 70 °C, 90 °C heating drastically increased (p < 0.05) cooking loss (CL) from 5% to > 15% since more immobilized water was pushed out as free water. Step cooling could mitigate the high-temperature-induced CL. The impact of heating strategies on the textural properties of chicken meat is much lower than that on CL. For both 70 °C and 90 °C cooked samples, step heating reduced (p < 0.05) their whiteness by increasing the yellowness. The storage modulus (G') increase during cooling is mainly driven by cooling leaded lower mobility. Overall, low-temperature ramping heating produced excellent meat gel with low energy consumption.

Effect of multiple freeze-thaw cycles on water migration, protein conformation and quality attributes of beef longissimus dorsi muscle by real-time low field nuclear magnetic resonance and Raman spectroscopy.

Repeated freezing and thawing (F-T) happens during long-term storage and transportation due to the temperature variation, causing quality deterioration of beef products and influencing consumer acceptance. This study was aimed to investigate the relationship between quality attributes, protein structural changes and water real-time migration of beef with different F-T cycles. The results showed that multiply F-T cycles damaged the muscle microstructure and protein structure tended to denature and unfold, led lower population of water reabsorbed, thus triggering the decrease of water capacity, especially a decrease of T21 and A21 of completely thawed beef samples, finally affected the quality, such as tenderness, color and lipid oxidation of beef muscle. Beef should not be abused by F-T cycles >3 times, the quality extremely degraded when subjected to 5 or more F-T cycles, and real-time LF-NMR provided a new aspect to help us control the thawing process of beef.

A Prebiotic Ribosylation of Pyrimidine Nucleobases Enabled by Metal Cations and Clay Minerals.

We report a prebiotically relevant solution to the N1-ribosylation of pyrimidine nucleobases, a well-known challenge to the RNA world hypothesis. We found that the presence of metal cations and clay minerals enable the previously unachievable direct ribosylation of uracil. Spectroscopy and chromatography analyses confirmed the formation of ribosylated uracil. The method can be extended to the ribosylation of 2-pyrimidinone. These findings are also compatible with the metal-doped-clay model, developed by our lab for the unified route of the selection of ribose and subsequent syntheses of nucleotide and RNA.

Phosphoproteome analysis of sarcoplasmic and myofibrillar proteins in stress-induced dysfunctional broiler pectoralis major muscle.

Postmortem changes of sarcoplasmic and myofibrillar protein phosphorylation in pectoralis major (PM) muscle of broilers under pre-slaughter stress were investigated. Broiler chickens were randomly distributed to unstressed control and transport under high environmental temperature groups. PM muscle samples of transport-stressed broilers were classified into normal or pale, soft and exudative (PSE)-like. Sarcoplasmic fraction in PSE-like meat had a higher global phosphorylation level than that in normal meat at the early postmortem stage. The myofibrillar proteins showed diverse phosphorylation patterns at different postmortem times. The stress-induced highly phosphorylated sarcoplasmic proteins were glycometabolic enzymes, which partially contributed to accelerated glycolysis rate. The phosphorylation levels of most sarcomeric proteins identified in the myofibrillar fraction were affected by postmortem time, implying their roles in regulating muscle rigor mortis development. This work contributes to a deeper understanding of the biochemical processes that may lead to stress-induced changes in meat quality.