Heparin: Determination with Ribonuclease

Abstract

Publisher Summary This chapter describes the enzymatic determination of heparin using ribonuclease. Heparin inhibits several enzyme reactions. It is most suitably determined by its inhibition of pancreatic ribonuclease. Like the coagulation of blood, the inhibition of ribonuclease is sensitive to small changes in the heparin molecule. This method permits the estimation of small amounts of heparin and the kinetics of the inhibition can be measured. Some “heparinoids,” for example, thrombocide and sulfonated polysaccharides with heparin-like activity, are estimated as heparin. As all the other existing methods can only be used for the estimation of “heparin-like activity,” this disadvantage is not very important. In contrast to the analytical methods, employing the effect of heparin on blood coagulation, the use of ribonuclease inhibition has the advantage of simple experimental conditions with a precisely defined reaction mixture and a linear relationship between the values obtained experimentally and the heparin concentration. Proteins that bind heparin or high salt concentrations interfere with the determination. The enzymatic method is based on the principle that heparin inhibits the breakdown of ribonucleic acid and cyclic pyrimidine nucleotides by ribonuclease. This inhibition is probably competitive and can be represented by the formula that is presented in this chapter.