title: Identification of novel proteolytic forms of osteocalcin in human urine.
abstract: In this study, we report the isolation and characterization of osteocalcin in human urine using mass spectrometry and N-terminal sequencing. Multiple proteolytic forms of osteocalcin were found, which consisted of 16-27 residues from the middle region of the molecule. Several fragments had residue Gly7 at the N-terminus and the most predominant was fragment 7-31. Additional fragments starting from residue Asp14 were detected in the samples of children and young adults. Immunochemical detection of urine osteocalcin fragments had a statistically significant negative correlation to bone mineral density in evaluation of urine samples from 75-year-old women. Thus, the measurement of osteocalcin fragments in urine may have potential applications in diagnostics related to disorders of bone metabolism.
authors.affiliation: Department of Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland. kaisa.ivaska@utu.fi
authors.forename: Kaisa K
authors.initials: KK
authors.lastname: Ivaska
authors.forename: Jukka
authors.initials: J
authors.lastname: Hellman
authors.forename: Johanna
authors.initials: J
authors.lastname: Likojärvi
authors.forename: Sanna-Maria
authors.initials: SM
authors.lastname: Käkönen
authors.forename: Paul
authors.initials: P
authors.lastname: Gerdhem
authors.forename: Kristina
authors.initials: K
authors.lastname: Akesson
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Obrant
authors.forename: Kim
authors.initials: K
authors.lastname: Pettersson
authors.forename: H Kalervo
authors.initials: HK
authors.lastname: Väänänen
mesh_terms: D000368:Aged; D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry; D015519:Bone Density; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005998:Glycine / Q000737:chemistry; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015675:Osteocalcin / Q000737:chemistry / Q000652:urine*; D017434:Protein Structure, Tertiary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors; D014556:Urine / Q000737:chemistry
chemical_list: D015675:Osteocalcin; D001224:Aspartic Acid; D005998:Glycine