A new criminologic procedure: study of L-cystine-aminopeptidase activity for the detection of seminal stains

L-Cystine-aminopeptidase (CAP) enzyme cleaves L-cystine-di-beta-naphthylamide substrate to beta-naphthylamine. The final product of this process is a violet azostain. CAP enzyme determination was developed for criminological procedures. CAP shows almost 100 times greater activity in human semen than in other body fluids. Samples taken at different time intervals (1 week, 1-3-6 months, 1 year, and 5-10 years) were investigated; they were dried on cloth and filter paper and then stored at room temperature for various time periods. The enzyme was also shown to be specific in the comparative studies performed with other human secretions (nasal discharge, saliva, vaginal secretion, feces, urine, breast milk) and fruit juices (raspberry, strawberry, apple, pear, plum, tomato, etc.).