An enzyme specific method for estimation of pyruvic acid radioactivity in biological samples

A method for the estimation of pyruvate radioactivity in complex biological samples is presented. After perchloric acid deproteinization, the samples were divided in two aliquots. All pyruvate was removed from the first aliquot with lactate dehydrogenase and NADH; the other was left undisturbed. Then all hydrophilic components of the sample were removed through an Amberlite XAD-7 column. The samples were treated with dinitrophenylhydrazine to obtain the corresponding hydrazones, which were retained in an Amberlite XAD-7 column and then were eluted with acetone and their radioactivity counted. The difference between both aliquots corresponded to the pyruvate radioactivity in the sample. No contamination by lactate, glycerol, glucose or amino acids was observed. The mean recovery of 5 determinations of pyruvate radioactivity was 91.3% +/- 1.0.