title: A novel arginine kinase with substrate specificity towards D-arginine.
abstract: We determined the cDNA-derived amino acid sequences of two arginine kinases (AK1, AK2) from the annelid Sabellastarte indica, cloned the cDNAs into pMAL plasmid and expressed them in E. coli. The phylogenetic analyses suggested that Sabellastarte AKs have evolved from a CK-related gene, not from the usual AK gene. The recombinant Sabellastarte AK1 showed a broad specificity towards various guanidine compounds, while the Sabellastarte AK2 mainly showed stronger activity for both D- and L-arginine, a very unique substrate specificity not seen before in usual AKs. We isolated guanidino compounds from the body wall musculature of Sabellastarte, and found that the major compound is D-arginine with a concentration of 4.85 +/- 0.51 mmol/kg. From these results, we suggest strongly that in Sabellastarte, D-arginine is the major phosphagen substrate and that the AK2 with substrate specificity towards D-arginine, catalyzes the phosphorylation of D-arginine.
authors.affiliation: Laboratory of Biochemistry, Faculty of Science, Kochi University, Kochi, 780-8520, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Uda
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000249:Adenosine Monophosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D001122:Arginine Kinase / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D019791:Guanidine / Q000737:chemistry; D008969:Molecular Sequence Data; D010802:Phylogeny; D011077:Polychaeta / Q000201:enzymology / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013379:Substrate Specificity / Q000235:genetics
chemical_list: D011994:Recombinant Proteins; D000249:Adenosine Monophosphate; D001120:Arginine; D001122:Arginine Kinase; D019791:Guanidine