A stability study of the esterase D isoenzymes

A study of the changes in electrophoretic patterns of EsD 1 and 2--1 phenotypes in progressively aging bloodstains was carried out and resulted in the establishment of criteria for the proper interpretation of such patterns. With these criteria, the EsD isoenzymes in dried bloodstains were found to have a maximum stability of four weeks. While degradation of the isoenzyme in fluid blood at 37 degrees C was complete by the third day, instability was not detected until the sixth week in fluid samples stored at 3 degrees C; the presence or type of anticoagulant had no observable effect on the 3 degrees C samples. When fluid blood was stored at room temperature, the presence of anticoagulant and preservative did not enhance the stabilityof EsD. Critrate-fluoride did not produce any observable effect; heparin, oxalate, and EDTA increased the rate of degradation, with EDTA being the most detrimental, reducing the stable period to three days.