Determination of Vitamin K-dependent Calcium Binding Protein Level in Rat Bone Using Radioimmunoassay and High-Performance Liquid Chromatography

Abstract

Using 20% formic acid extracts of femur cortical bones from 4 to 52 weeks old female rats, the levels of vitamin K-dependent bone γ-carboxyglutamic acid (Gla) containing protein (BGP) were determined by radioimmunoassay (RIA) and high-performance liquid chromatography (HPLC) as ratio of Gla/Glu and the results were discussed in relation with bone density. BGP levels determined by either RIA and HPLC were highly correlated to bone density, which reflects the stage of bone calcification. Moreover, a positive correlation was observed between BGP content determined by RIA and the ratio of Gla/Glu determined by HPLC. BGP content was about 2 μg/mg dry bone powder.