Studies on the Role of Sialic Acid in Fibrinogen: Determination of the Sialic Acid in Fibrinogen by High Performance Liquid Chromatography

Abstract

Fibrinogen,the coagulation factor I,is a plasma glycoprotein capable of clotting, which leads to stoppage of bleeding from damaged tissues.Much of the role of carbohydrate moiety of fibrinogen in the fibrinogen-fibrin conversion through the action of thrombin remains to be clarified yet. Fibrinogen in patients with certain liver diseases contains more sialic acid residues than in normal subjects1-5).In such patients, clotting time through the action of thrombin tends to be prolonged.There are fibrinogens that have hereditary abnormalities in their molecular structure. Some of such abnormal fibrinogen molecules,including Fibrinogen-Nancy6), Fibrinogen-Copenhagen7)and FibrinogenParis II8),result from an abnormality in the number of sialic acid residues,hindering fibrins in polymerization.These findings strongly suggest that sialic acid present in fibrinogen may affect the polymerization mechanism involved in the formation of blood clots following hemorrhage. Colorimetry by the thiobarbituric acid method of Warren9)has been used for the determination of sialic acid,which is liberated from fibrinogen by acid or enzymic hydrolysis.This method presents many problems such as leading to errors of measurement resulting from the process of determination that is very complicated,and requiring the use of a toxic chemical agent. In order to elucidate the role of sialic acid *Department of Biochemist ry,Meiji College of Pharmacy,Tokyo