Deoxyribonuclease I phenotyping from saliva stains

Good typing results were obtained using a newly developed method for extrac tion and purification of deoxyribonuclease I(DNase I) from saliva stains. P reviously, DNase I phenotyping from saliva stains has been unsuccessful bec ause of low enzyme activity and heavy contamination. Salivary DNase I was e xtracted from stains using phosphate buffer containing Nonidet P-40. Extrac ts were purified using Phenyl Sepharose CL-4B gel. Electrophoresis was perf ormed, and DNase I was successfully phenotyped. All of the DNase I phenotyp es, which were obtained from saliva stains using this new method, were iden tical to the phenotypes determined from urine samples. Moreover, DNase I wa s correctly phenotyped from saliva stains that had been stored for over thr ee months at room temperature or at 37 degrees C. These results suggest tha t DNase I polymorphisms provide valuable information for forensic character ization of saliva stains.