Activities of neutral RNase in ascitic fluid of patients with non-tumorous simple ovarian cyst and with serous cystadenocarcinoma were determined and compared to investigate whether ascitic neutral RNase activities were changed in ovarian eitherial carcinomas. Neutral RNase in ascitic fluid of serous cystadenocarcinona seen most frequently among the ovarian epitherial carcinomas were isolated and analyzed by DEAE-cellulose column chmatography, and properties of the enzyme isolted were studied.
1. A slight but significant increase in neutral RNase activities againse polycytidylat (poly C) was observed in asctic fluid of serous cystadenocarcinoma as compared with that of non-tumorous simple ovarial cyst.
2. Neutral RNases in ascitic fluid of the ovarian epitherial cancer were isolated by DEAE-cellulose column chromatography into two peaks (peak Ⅰand Ⅱ) active against poly C.
3. The pH-activity curves for and influence of Mg²on both peak Ⅰand Ⅱ neutral RNases were studied in the present study. While the pH-activity curves for the two peak enzymes appeared to be similar to each other, the influence of Mg² on the two peak enzymes showed diffrently with one another.
4. Neither peakⅠand Ⅱ neutral RNases in ascitic fluid of the ovarian epitherial cancer were inhibited by para-hydroxymercuribenzotae(PHMB), a selective inkibitor of sulfhydryl(SH) compounds, nor activated by reduced glutathione (GSH). These results suggested tht the catalytic sites for both peakⅠand Ⅱ neutral RNases were not composed of SH groups.
5. Substrate specificities in order of decreasing activity were poly C, polyuridylate(poly U) and RNA for ascitic peak Ⅰneutral RNase and poly C, RNA and poly U for ascitic peak Ⅱ enyem. Birtually no activity against polyadenylate (poly A) or polyguanylate (poly G) were observed in both ascitic peak Ⅰand Ⅱ neutral RNases. These results showed tht very high affinity to cytidine internucleotide linkagesof RNA of polyribouncleotides was observed in both peakⅠand Ⅱ neutral RNases, but substrate specificities were different form peak Ⅰneutral RNase from peakⅡ enzyme.
The present sutdy suggested that at least two different neutral RNases might be present in ascitic fluid of the ovarian epitherial cancer. It is unclear, however, whether neutral RNase specific to the cancer is present in the ascitic fluid.
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