title: A novel photoprotein from oceanic squid (Symplectoteuthis oualaniensis) with sequence similarity to mammalian carbon-nitrogen hydrolase domains.
abstract: A 60-kDa photoprotein was selectively extracted from squid photogenic organ with 0.6 M KCl solution at pH 6 as luminescence-active forms. The photoprotein with fluorescence chromophore was eluted from size-exclusion HPLC mainly as oligomeric forms (about 200 kDa or more) with a trace amount of monomeric form of about 60 kDa. A limited tryptic digestion of the KCl-extract induced the cleavage into a 40-kDa fragment and a 16-kDa N-terminal fragment and the conversion to the monomeric form which still retained luminescence activity. Under UV light the 60-kDa protein and its 40-kDa fragment emitted fluorescence. Immunoblot analysis using specific antibody showed specific expression of the 60-kDa protein in the photogenic organ. Amino acid sequences of the 60-kDa photoprotein, its 40- and 16-kDa fragments, and six peptides from the Lys-C digest revealed no sequence similarity to known photoproteins but significant similarity to the carbon-nitrogen hydrolase domain found in mammalian biotinidase and vanin (pantetheinase).
authors.affiliation: Laboratory of Organic Chemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Fujii
authors.forename: Jung-Youb
authors.initials: JY
authors.lastname: Ahn
authors.forename: Masaki
authors.initials: M
authors.lastname: Kuse
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mori
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Matsuda
authors.forename: Minoru
authors.initials: M
authors.lastname: Isobe
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D043523:Biotinidase; D002244:Carbon / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D049832:Decapodiformes / Q000378:metabolism; D058851:GPI-Linked Proteins; D006801:Humans; D006867:Hydrolases / Q000737:chemistry; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009792:Oceans and Seas; D010455:Peptides / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D058851:GPI-Linked Proteins; D008164:Luminescent Proteins; D010455:Peptides; D011189:Potassium Chloride; D002244:Carbon; D006867:Hydrolases; D000581:Amidohydrolases; C022314:pantetheinase; D043523:Biotinidase; D009584:Nitrogen