Osteocalcin, or bone Gla protein (BGP), is the major non-collagenous protein of bone matrix. It has a molecular weight of approximately 5800 Dalton and consists of 49 amino acids, including three residues of gamma-carboxyglutamic acid.
Osteocalcin is synthesised in bone by osteoblasts. After production, it is partly incorporated into the bone matrix and partly delivered to the circulatory system.
The precise physiological function of osteocalcin is still unclear. A large number of studies have shown that the circulating level of osteocalcin reflects the rate of bone formation.
The N-MID® Osteocalcin ELISA is based upon the application of two highly specific monoclonal antibodies (mAbs) against human osteocalcin. An antibody recognising the mid-region (amino acids 20-29) is used as the capture antibody, and for detection a peroxidase conjugated antibody recognising the N-terminal region (amino acids 10-16) is used. In addition to intact osteocalcin (amino acids 1-49) the N terminal mid-fragment (amino acids 1-43) is also detected.
