Investigation of ribonuclease isozymes by an electrophoretic ultra-violet method

Acid ribonuclease and alkaline ribonuclease isoenzymes in plasma of patients with decreased glomerular filtration rate

Removal of low molecular weight proteins from plasma by kidneys depends on glomerular filtration rate (GFR), protein-glomerular membrane electric charge, steric interactions and a number of functionally active nephrons present in the kidneys. There is a well documented relationship between the concentration of low molecular weight proteins in plasma and GFR value in patients with impaired renal function. Accumulation of low molecular weight proteins in plasma along with a decrease in GFR value may in the long run enhance formation of protein tissue deposits known as various forms of amyloidosis. In this paper we present studies on plasma concentrations of acid leukocyte-type ribonuclease (RNase) and alkaline pancreatic-type RNase and GFR value in 54 patients with renal failure. RNase isoenzymes' activities were assayed by measuring their enzyme activities manifested as ability to decompose yeast RNA and assay of digestion products' concentration by spectrophotometry. The studies show that decreasing filtration rate produces an increase in serum activities of both acid and alkaline RNases, which is proportional to the logarithm of GFR value. However, the increase rate vs. GFR value is by four times higher for acid RNase then for alkaline RNase. Acid RNase in human plasma is mostly of leukocytic origin and differs from pancreatic-type alkaline RNase, which is of pancreatic origin. The obtained results may suggest that leukocyte originating proteins essentially contribute to low molecular weight protein accumulation in plasma of patients with chronic renal insufficiency.

Sialic acid residues contribute to the heterogeneity of human serum ribonuclease: demonstration by isoelectric focusing and neuraminidase treatment of serum

Ribonuclease (RNase) activity from human serum appears as multiple zones of activity following isoelectric focusing in thin layer polyacrylamide gel. At least one but not all of these zones is cross reactive with rabbit antibovine pancreatic RNase A antiserum. Treatment of serum or partially purified serum RNase with neuraminidase reduces the complexity of the serum RNase banding pattern to a major band which focuses at a pH of 9.5 or greater and a minor zone of activity which focuses at about pH 6.0-6.2. Trypsin does not affect the pattern. Thus, sialic acid residues account for a large portion of the heterogeneity of human serum RNase. Neuraminidase treatment is requisite for evaluating RNase from serum and certain other sources.

Purification and characterization of ribonucleases from human seminal plasma

Four ribonucleases (RNAases I-IV) have been purified to homogeneity from human seminal plasma by precipitation with 40-75%-satd. (NH4)2SO4, followed by chromatographies on concanavalin A-Sepharose 4B, DEAE-cellulose phosphocellulose, agarose-5'-(4-aminophenylphospho)uridine 2'(3')-phosphate (RNAase affinity column) and Sephadex G-75 or G-100. The homogeneity of these RNAases was confirmed by polyacrylamide-gel electrophoresis. Mr values for these purified RNAases were 78 000, 16 000, 13 300 and 5000 as estimated by gel filtration. Enzyme activities of RNAases I, III and IV were inhibited by Mn2+, Zn2+ and Cu2+ and activated by Na+, K+, Ba2+, Mg2+, Fe2+ and EDTA, whereas that of RNAase II was inhibited by Ba2+, Mg2+, Fe2+, Mn2+, Zn2+ and Cu2+ and activated by Na+, K+ and EDTA. RNAases I, II and IV demonstrated a higher affinity for poly(C) and poly(U) or yeast RNA, whereas RNAase III preferentially hydrolysed poly(U) over poly(C) and yeast RNA. In the presence of 5 mM-spermine, RNAase I was dissociated to a low-Mr (5000) enzyme with an increase in total RNAase enzymic activity. Xenoantiserum to each RNAase was raised and evaluated by immunoprecipitation and immunohistochemical methods. Anti-(seminal RNAase III) antiserum showed no immunological cross-reaction with RNAases of other human origin, whereas anti-(seminal RNAase I), -(RNAase II) and -(RNAase IV) antisera exhibited indistinguishable immunological reactions with serum RNAase and other human RNAases, except that anti-(seminal RNAase I) and -(RNAase antisera IV) did not react with pancreatic RNAases. Seminal RNAases I and IV were identical immunologically as shown by anti-(RNAase I) and anti-(RNAase IV) in immunodiffusion. Immunohistochemical study revealed that, among human tissues examined, only prostate expressed seminal RNAase III. These results suggested that human seminal RNAase I may be an aggregated molecule of RNAase IV and that seminal RNAases II and IV are similar to serum RNAases, whereas seminal RNAase III is a prostate-specific enzyme.

Activities of serum acid ribonuclease in patients with malignant neoplasms or with renal failure

The activities of serum acid ribonuclease (RNase) were determined in patients with malignant neoplasm or with renal failure. The levels were markedly increased in myelogenous leukemia and renal failure, and only slightly increased in solid cancers, lymphoid malignancies and multiple myeloma. These increases correlated significantly with serum LDH activity in myelogenous leukemia and with creatinine levels in other malignancies or renal failure. The acid RNase content of granulocytes was 22.7-fold higher than that of lymphocytes. The increase of serum acid RNase may suggest an increased granulocyte destruction in myelogenous leukemia and a reduced glomerular filtration in other malignant neoplasms and renal failure.

Purification, characterization and development of radioimmunoassay of human liver ribonuclease

Human liver ribonuclease (RNase) was purified 36000-fold into an electrophoretically homogeneous state by column chromatography on phosphocellulose, gel filtration, poly(G) affinity chromatography, and heparin affinity chromatography. The molecular weight of the RNase estimated by SDS disc electrophoresis was 19,500. RNase was a heat- and pH-stable protein, and optimum activity was obtained at pH 7.0. The radioimmunoassay (RIA) for human liver RNase has been developed and the assay was shown to be sensitive (20 ng/ml), reproducible and specific. A good parallel relationship was observed between the standard curve and the dilution curves for serum and urine. No cross-activity was demonstrated between human liver and pancreatic RNase (less than 1%). In 44 normal subjects, the mean serum concentration of liver RNase determined by the RIA was found to be 99.4 ng/ml (SD +/- 66.3).

Isozymes of ribonuclease in human serum and urine. I. Methodology and a survey of a control population

Methods are presented for the electrophoretic analysis of ribonuclease (RNase) enzymes in human serum and urine. Protocols for sample treatment, electrophoresis, and the RNase zymogram technique are described. With the application of these methods, RNase from serum and urine was separated into components differing on the basis of charge (charge isomers or "isozymes"), but not differing with respect to hydrolyzable sialic acid residues. Preliminary characterization of the electrophoretically separated components showed that some of the RNase species have different properties (pH optima and substrate preference). The major urine RNase isozymes appeared to be distinct from the major serum RNase isozymes. A survey of a control population indicated that the major serum and urine RNase enzymes are not genetically polymorphic.

Assessment of the clinical usefulness of serum ribonuclease assays: an indicator for the detection of pancreatic cancer

To evaluate diagnostic usefulness for pancreatic cancer, serum ribonuclease (RNase) level was determined in three groups of subjects; 1) normal volunteers as control, 2) patients with histologically determined pancreatic cancer, and 3) patients with miscellaneous diseases other than pancreatic cancer. A small increase of RNase values was recognized with age in the normal subjects and in the patients with nonpancreatic diseases, if renal function was normal. The mean RNase level in the control subjects was 97 +/- 41.2 units. A marked elevation of serum RNase level was demonstrated in the patients with pancreatic cancer (p less than 0.001) and in the patients with renal dysfuction, but no significant rise was noticed in the patients with pancreatitis. Mean values of RNase in the patients with pancreatic cancer and renal dysfuncton were 368 +/- 146 units and 342 +/- 78.1 units respectively. RNase values above 300 units were recognized in 15(71%) out of 21 patients with pancreatic cancer. Seven cases with elevated RNase over 300 units other than non-pancreatic malignancy and renal dysfunction were noticed in 6 instances of obstructive jaundice and in one instance of early gastric cancer (an 84-year-old male). The above-stated findings indicate that serum RNase determinations can be utilized as a diagnostic indicator for pancreatic cancer.

Alteration of human serum ribonuclease activity in malignancy

A review of the literature and current biochemical studies is presented which provides significant evidence of alteration in the level of the enzyme ribonuclease activity in cancer. Current studies reveal that 80% of all cancer patients have alteration in ribonuclease activity and that individuals known to be at high risk for the development of cancer also demonstrate significant alteration of ribonuclease activity. It is noted that while elevation of serum ribonuclease exists within the cancer state and appears to be independent of clinical status (relapse, remission, or cured), diminished activity is found within the tumor itself. Animal models are reviewed which demonstrate that ribonuclease activity becomes elevated in the murine species subsequent to the transplantation of tumor and following the infection of the host with oncogenic virus. The occurrence of elevated ribonuclease activity in high tumor incidence strain mice long before the development of overt tumor is alos discussed. To date it is not possible to assign a specific function to the changes in the level of ribonuclease in connection with the cancer state. However, evidence indicating that tumor chemotherapy is generally associated with early elevation of ribonuclease activity within the tumor cell suggests that increased ribonuclease activity may play a role in the process by which the host restricts neoplastic transformation. The potential of this enzyme as a biochemical marker in cancer is discussed.

Plasma ribonuclease: a marker for the detection of ovarian cancer

There were no significant differences between the mean blood plasma (leukocyte-free) RNAase activity among 128 healthy women volunteers age 13-70 and 49 women with benign gynecological tumors. Exceptions to this finding were three apparently healthy women volunteers who had plasma enzyme activity which was higher than two standard deviations from the mean of the control subjects. Increased plasma RNAase activity was also demonstrated for 21 of 22 patients with ovarian carcinomas of differential histological types. This group included two patients with Stage IA, two patients with Stage IC ovarian carcinoma, and 17 patients with advanced ovarian carcinoma. The one exception was a patient with a well encapsulated, mucinous cystadenocarcinoma, Stage IA. The plasma RNAase activity returned to normal values in all of the cancer patients who had no clinical evidence of residual malignant tissue after surgical treatment. However, the enzyme activity also returned to a normal value in one of the 17 women in whom all of the malignant tissue was not removed. These data indicate that plasma RNAase activity can be utilized as a tumor marker for the presence of ovarian malignancies of various histological types, and to differentiate between malignant and benign neoplasms.

Purification and properties of alkaline ribonuclease from human serum

1. Five alkaline ribonucleases (EC 3.1.4.22) were purified about 140- to 1900-fold from human serum by phosphocellulose and DEAE-cellulose chromatographies and Sephadex G-75 filtration, with a total recovery of 22%. These were designated as RNAases 1-5. 2. Optimum activities were observed at pH 8.5-8.7 for RNAases 1-4, and at pH 7.5 for RNAase 5. The molecular weights of these enzymes were estimated by gel filtration as 45 000, 32 000, 20 000, 13 000 and 8500, respectively. 3. These RNAases were found to be heat-labile proteins but are markedly stabilized with bovine plasma albumin. The reaction was activated by Na+, K+, Mg2+ and Ca2+, and inhibited by Co2+, Fe2+, Cu2+ and Zn2+. EDTA had little effect on the velocity of the reaction. Spermine caused 2- to 7-fold activation. 4. Among the substrates examined, these RNAases preferentially hydrolyzed pyrimidine bodies and except for RNAase 5 had a higher affinity for poly(C) than poly(U) as substrate. Each enzyme was free from other nucleolytic enzymes and hydrolyzed only RNA.

Purification and properties of human acid-thermostable ribonucleases, and diagnosis of childhood pancreatic fibrosis

Acid-thermostable ribonucleases were isolated from human pancreas, duodenal contents, liver, spleen, serum and urine, and purified 15--1000-fold. The pH optima, ionic requirements, and some of the specificity requirements, of these enzymes were investigated. The isolated enzymes formed two distinct groups: (a) The ribonucleases of the pancreas, duodenal contents and fraction A of serum and urine exhibit a pH optimum of 8.5, are inhibited by An2+ and Cu2+, and relatively rapidly hydrolyze the synthetic substrate uridine 3'-(alpha-naphthylphosphate); (b) the ribonucleases of the liver and spleen, and of fractions B of the serum and urine, with a pH optimum of 7, are less sensitive to An2+ and Cu2+, and exhibit negligible activity versus uridine 3'-(alpha-naphthylphosphate). Determination of the serum level of pancreatic-type ribonuclease activity, with the use of uridine 3'-(alpha-naphthylphosphate) or RNA as substrates, appears to be a valid diagnostic tool for pancreatic fibrosis in children.