The use of sperm-specific lactate dehydrogenase isoenzyme for the identification of semen in dried stains

The sperm-specific lactate dehydrogenase (LDH) isoenzyme (Blanco and Zinkham, 1963; Goldberg, 1963) separated from other LDH isoenzymes of semen by Polyacrylamide gel electrophoresis has been found to be suitable for specific differentiation of human semen from other human body fluids and semen of commonly encountered animals. Seminal isoenzymes were found to be stable even 4 weeks after storage in tropical conditions. The method gave substantially more positive results than microscopic identification of spermatozoa when applied to a large number of relatively old stains on actual crime articles. It is therefore valuable in a large number of cases involving normal males and also in interpreting results of immunological and enzymological individualisation of semen stains.