Abstract: The present invention provides synthetic peptide derivatives represented by the formulaP.sup.1 -R.sup.1 -P.sup.2wherein P.sup.1 is a peptide having an amino acid sequence in the SEQ ID NO.:1 of the Sequence Listing, or analogues thereof; P.sup.2 is a peptide having an amino acid sequence in the SEQ ID NO.:2 of the Sequence Listing, or analogues thereof; R.sup.1 denotes a linker with a property that does not interfere with the activity of the each peptide P.sup.1 and P.sup.2 to bind N-terminal end of the peptides P.sup.1 and P.sup.2.The present invention also provides a pharmaceutical composition for the treatment of bone related diseases comprising said peptide derivatives, or a therapeutically acceptable salt thereof, and a pharmaceutically acceptable carrier.The present invention also provides a method of treating bone related diseases in a mammal comprising administering thereto an effective amount of said peptide derivatives, or therapeutically acceptable salts thereof.

Abstract: The present invention provides the sequence of the novel bone-related protein OSF-2 which can be obtained from mammalian bone tissues. The invention further provides a method of production of OSF-2 by recombinant techniques.

Abstract: A bone-related protein named OSF-8 which is obtained from bone tissue of a mammal including mouse or human, and a process for its production. This protein is a novel naturally occurring mammal protein which belongs to a group of sulfatases. OSF-8 degrades the sulfate groups of the sugar chains of proteoglycan, which makes up the cartilage matrix, during the replacement of cartilage into bone tissue at the stage of osteogenesis. OSF-8 can be used as an agent for treating bone metabolic diseases, and its high organ specificity for bones enables its use as a diagnostic reagent for bone metabolic diseases.

Abstract: A method for screening for osteoporosis comprising bone sialoprotein of mammals. Osteoporosis can be screened by bringing the body fluid sample collected from a living body into contact with the above-mentioned diagnostic agent to immunochemically detect the antibody which is present in the said sample and specifically reacts with the said diagnostic agent.