title: Purification and identification of two carnosine-cleaving enzymes, carnosine dipeptidase I and Xaa-methyl-His dipeptidase, from Japanese eel (Anguilla japonica).
abstract: Three enzymes, carnosine dipeptidase I (EC 3.4.13.20, CNDP1), carnosine dipeptidase II (EC 3.4.13.18, CNDP2), and Xaa-methyl-His dipeptidase (or anserinase: EC 3.4.13.5, ANSN), are known to be capable of catalyzing the hydrolysis of carnosine (β-alanyl-l-histidine), in vertebrates. Here we report the purification and identification of two unidentified carnosine-cleaving enzymes from Japanese eel (Anguilla japonica). Two different dipeptidases were successfully purified to homogeneity from the skeletal muscle; one exhibited a broad substrate specificity, while the other a narrow specificity. N-terminal amino-acid sequencing, deglycosylation analysis, and genetic analysis clearly revealed that the former is a homodimer of glycosylated subunits, encoded by ANSN, and the latter is another homodimer of glycosylated subunits, encoded by CNDP1; that is, Xaa-methyl-His dipeptidase, and carnosine dipeptidase I respectively. This is the first report on the identification of carnosine dipeptidase I from a non-mammal. Database search revealed presence of a CNDP1 ortholog only from salmonid fishes, including Atlantic salmon and rainbow trout, but not from other ray-finned fish species, such as zebrafish, fugu, and medaka whose genomes have been completely sequenced. The mRNAs of CNDP1 and ANSN are strongly expressed in the liver of Japanese eel, compared with other tissues, while that of CNDP2 is widely distributed in all tissues tested.
authors.affiliation: Science of Marine Resources, United Graduate School of Agricultural Science, Kagoshima University, Kagoshima, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Oku
authors.forename: Seiichi
authors.initials: S
authors.lastname: Ando
authors.forename: Hsin-Chun
authors.initials: HC
authors.lastname: Tsai
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiozaki
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Nishi
authors.forename: Shoji
authors.initials: S
authors.lastname: Yamada
mesh_terms: D000595:Amino Acid Sequence; D000811:Anguilla; D000818:Animals; D002336:Carnosine / Q000378:metabolism*; D004150:Dipeptidases / Q000302:isolation & purification* / Q000378:metabolism*; D029941:Fish Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D029941:Fish Proteins; D002336:Carnosine; D004150:Dipeptidases