{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nThe enzymatic activity detailed in the first study (citing"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "describes a protein originally unidentified in chicken pectoral muscle that was later recognized as ATPGD1—a member of the ATP‐grasp family. This enzyme catalyzes the synthesis of carnosine and homocarnosine by ligating β-alanine (with an efficiency 15–25-fold higher compared to γ-aminobutyrate) with histidine derivatives. The reaction mechanism involves ATP conversion into ADP rather than AMP as originally thought, providing critical insight into its catalytic chemistry and substrate specificity in vertebrate tissues."}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nThe second study (citing"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "extends these biochemical findings to a physiological context. Here, a mouse model deficient in carnosine synthase (Carns1) reveals that the complete loss of carnosine and related histidine-containing dipeptides does not impair skeletal muscle contraction or pH buffering. However, with aging, these mice develop olfactory deficits, which are associated with a decline in olfactory receptor neurons and elevated protein carbonylation in the olfactory bulb. These results imply that the dipeptides synthesized by this enzyme play a protective, likely antioxidant, role in preserving neuronal integrity, particularly during aging."}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nTogether, the studies underscore the dual biochemical and protective functions of the carnosine synthase gene product. By efficiently generating dipeptides such as carnosine and homocarnosine, this enzyme not only contributes to muscle performance and metabolism but also supports the long-term maintenance of neural tissue integrity against oxidative damage. Although the query mentions MIR6860, the abstracts focus on the functions of carnosine synthase, suggesting that any association with MIR6860 would be indirect, perhaps through broader regulatory networks governing dipeptide homeostasis.\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Jakub Drozak, Maria Veiga-da-Cunha, Didier Vertommen, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1)."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M109.095505"}], "href": "https://doi.org/10.1074/jbc.M109.095505"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20097752"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20097752"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Lihua Wang-Eckhardt, Asisa Bastian, Tobias Bruegmann, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2020)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.RA120.014188"}], "href": "https://doi.org/10.1074/jbc.RA120.014188"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "33040025"}], "href": "https://pubmed.ncbi.nlm.nih.gov/33040025"}]}]}]}