Purification of lactate dehydrogenase isoenzymes one, two, and three from human erythrocytes

Lactate dehydrogenase (LD) isoenzymes 1, 2, and 3 were prepared from human erythrocytes by sequential ion-exchange chromatography followed by general-ligand (AMP analog) affinity chromatography. Respective yields, purification factors, and specific activities (kU per gram of protein) were 25%, 4394-fold, and 209.7; 40% 4385-fold, and 199.1; and 18%, 7565-fold, and 192.9. The respective preparations contained less than 0.5% of contaminating LD isoenzyme activity as judged from electrophoresis on thin-layer agarose, were homogeneous as judged by electrophoresis on polyacrylamide gel (both in the presence and absence of sodium lauryl sulfate), and showed minor contamination by other LD isoenzymes as judged by analytical isoelectric focusing. We think that these preparations would be useful as human-based calibrating or reference materials. Their purity is such that these preparations could also be used as antigens for the development of suitable antisera.