The Purification Of Biliary Protein And The Simulation Biomineralization Of Calcium Carbonate In Vitro

Gallstone is a worldwide common disease and an abnormal biomineralization. It is unclear about the formation mechanism of gallstone. Matrix proteins are known to be essential for biomineralization and may be an important factor in the formation and growth of gallstone. In this paper, we extracted a kind of protein from pig bile by chromatography. We studied the interaction between this protein and Mg2+, calcium carbonate in order to find the possible interaction mechanism between biomacromole -cule and inorganic salt.The dissertation consists of three parts. (1) Biliary protein was purified and determined;(2) The interaction between Mg2+ and biliary protein was studied by spectroscopy;(3) The simulation biomineralization of calcium carbonate was studied.1 Biliary protein was isolated and purified by ammonium sulfate fraction and Sephadex G-75 gel filtration column chromatograph from complex pig bile. FT-IR showed the biliary protein was a glycoprotein. Its molecular weight was determined as 34.7 KD by MS. Both sodium dodecylsulphate-polyacrylamide gel electrophoresis and MS proved the protein is pure.2 The interaction between Mg2+ ion and biliary protein was studied by fluorescence spectroscopy and UV-Visible spectroscopy. The decrease of fluorescence intensity and UV-vis absorption showed that there is interaction between the Mg2+ ion and biliary protein. The Stern -Volmer constant showed the stable coordination compound was formed by Mg2+ ion and biliary protein. This study will shed light on further exploring the formation mechanism of gallstone.3 There are abundant calcium salts in gallstones, especially calcium carbonate. In the present work, we employed calcium-binding proteins (CBP) in order to assess its capability to induce the formation of CaCO3 in biological circumstance in vitro. The effect of CBP on kinetic of the growth of calcium carbonate was examined by determination of conductivity and pH value. The results showed that CBP inhibited the growth of CaCO3.The appearance and morphology of CaCO3 which obtainedfrom the system with and without CBP were observed by FT-IR, XRD and SEM. From the result we learned that they were all calcite regardless of the different appearance. The possible formation mechanism of CaCO3 was discussed. At the same time the calcium carbonate was induced by pepsin in dilute bile in order to simulate the bile. The result shows that the biomacromolecule conformation varied with the concentration of biomacromolecule and the morphology of CaCO3 was different when the concentration of biomacromolecule was different.