Studies on forensic applications of human ribonucleases

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Although there are many nucleolytic enzymes in human body fluids, these enzymes have not been used in the field of forensic sciences at all. So, this study was designed in order to make a wider variety of applications of these enzymes in this field. (1) Two types of deoxyribonuclease, DNases I and II, were purified separately from human urine, and then characterized in detail. By means of the combined technique of isoelectric focusing and immunoblotting or the newly devised zymogram method, at least ten distinct phenotypes could be detected in human urinary or serum DNaseI. From the genetic surveys, it has been known that DNase I was controlled by four codominant alleles at a single autosomal locus with the favorable distribution of its gene frequencies. Therefore, the genetic polymorphism of human DNase I was found to be useful as an effective tool for forensic individualization. Next, we discovered the existence of genetic polymorphism in the activity levels of urinary and leukocytic DNase IIs : the Japanese study population could be classified into two distinct types, high-activity and low-activity. From the family study, DNaseII. was found to be controlled by two alleles at a single autosomal locus the low activity type was due to an recessive allele. (2) We succeeded in purification and characterization of different sibonucleases (RNasea) from human erythrocytes, spleen and kidney. The enzymological and immunological properties of the RNases were very similar but there was a wide difference among their carbohydrate compositions. The organ- or tissue-specificities of human RNases may be due to the differences in their carbohydrate moieties. (3) We discovered the existence of genetic polymorphism in human protein C inhibitor, a factor in the system of blood coagulation and fibrinolysis, using isoelectric focusing electrophoresis and immunoblotting with specific antibodies.