ABSTRACT In order to reduce the health risks associated with red meat as listed by the World Health Organization, the work presented in this article aimed to elucidate the interaction between 5′-CMP–supplemented feed and N -glycolylneuraminic acid (Neu5Gc) in experimental animals in vivo. 5′-CMP was added to the diet of 90-, 180-, and 270-day-old Xiang pigs, and after 30 days, the Neu5Gc contents, physicochemical parameters, and free amino acid contents of muscle and internal viscera were measured by high-performance liquid chromatography coupled with fluorescence detection. The mechanism by which 5′-CMP affects Neu5Gc contents was investigated using molecular docking. Results show that 5′-CMP significantly decreased the Neu5Gc content in 180-day-old Xiang pigs ( P < 0.05) but had no effect on the Neu5Gc contents in 90- and 270-day-old Xiang pigs. Umami amino acids were significantly increased in 180-day-old Xiang pigs. In the 90- and 270-day-old pigs, histidine increased by 10.38 and 17.87%, respectively. The other free amino acids were either reduced or not affected. Moreover, the 5′-CMP–supplemented diet did not affect the physicochemical parameters of the longissimus muscle in the Xiang pigs. 5′-CMP could occupy almost all the sialyltransferase active-site residues but not His302 and showed inhibition of the sialyltransferase activity. The results provided an experimental basis for the subsequent reduction of Neu5Gc in red meat before slaughter.
Nucleotides, such as uridine 5′-monophosphate (5′-UMP) and cytidine 5′-monophosphate (5′-CMP), are heavily demanded as food additives, dietary supplements, and medicinal intermediates. Although enzymatic phosphorylation is an effective approach to producing these nucleosides, its practical application is challenging due to the need for the expensive enzymes and coenzyme guanosine-5′-triphosphate (GTP). Here we prepared biocompatible calcium-based nanoflowers incorporated with cascade enzymes, uridine-cytidine kinase (UCK) and acetate kinase (ACK), for the production of nucleotides. The spatial distribution of these enzymes was optimized to maximize their catalytic performances. The most active nanoflowers (Ca 3 (PO 4 ) 2 & ACK)& UCK that display the rate-limiting enzyme UCK on the outer layer were used in a packed-bed reactor for continuous synthesis of 5′-UMP and 5′-CMP. The catalytic performance of the catalyst retained over 80% within 10 h, showing good operational stability.
危险品化学品经营许可证（带存储）