Identification of semen in stain by determination of the specific activity of L-tartrate-inhibitable acid phosphatase.

For identification of semen in stain the specific activity of L-tartrate-inhibitable acid phosphatase (ACP) was determined. With each stain extract, both enzyme activity and protein concentration were determined, and the specific activity (enzyme activity/protein concentration) was calculated. Seminal stains showed a value of 23.8 +/- 15.2 (mean +/- SD) IU/mg protein, while vaginal fluid stains showed a value of 0.088 +/- 0.049 IU/mg protein. Stains of other body fluids did not show any L-tartrate-inhibitable ACP activity. Furthermore, only eight of 30 plant juice stains showed any levels of L-tartrate-inhibitable ACP, although all plants tested showed ACP activity. As the present method enables us to analyze forensic samples quantitatively, it seems to be useful for forensic practice.