Acid Ribonuclease Research Articles

Clinical significance of serum ribonuclease (RNase) assay in acute leukemia

The clinical significance of serum ribonuclease (RNase) assay in acute leukemia was studied. Serum RNases were assayed by the method of Akagi et al. with slight modifications in the serum samples obtained from 50 cases of healthy subjects, 55 cases of acute leukemia before therapy, 18 chronic myelocytic leukemia before therapy, 13 chronic myelocytic leukemia under treatment and 20 reactive leukocytosis. The ratio of acid RNase to alkaline RNase activities (Ac/Al ratio) was statistically increased in acute promyelocytic leukemia, acute myeloblastic leukemia [M2], acute myelocytic leukemia and erythroleukemia (leukemic stage) compared with those in healthy subjects (P less than 0.001). All cases of acute promyelocytic leukemia and most of the acute myeloblastic leukemia [M2], acute myelomonocytic leukemia and erythroleukemia cases had an Ac/Al ratio of above 1.0. In remission of acute leukemia, it is noteworthy that acid and alkaline activities showed no substantial difference from those of healthy subjects. While, on relapse of acute leukemia cases, showing Ac/Al ratio above 1.0 in pretreatment state, Ac/Al ratio increased to above 1.0. Thus, the assay of serum RNases and the calculation of Ac/Al ratio might be an additional method for diagnosing acute leukemia and for assessing their remission and recurrence in some type of acute leukemia.

Serum alkaline ribonuclease derived from vascular endothelial cells is raised in patients with rheumatoid vasculitis.

We investigated the mechanisms of the marked increase of alkaline ribonuclease (RNase) in the sera of patients with rheumatoid arthritis associated with vasculitis. Among various tissues examined, blood vessels contained higher levels of alkaline RNase than acid RNase. Cultured human endothelial cells contained significantly higher amounts of alkaline RNase than acid RNase. In contrast, acid RNase was predominant in most other tissues and cells. Endothelial cells cultured with sera from patients with vasculitis released alkaline RNase into the extracellular medium. The phosphocellulose chromatographic profile of these sera differed from that of sera from healthy subjects. These results imply that the alkaline RNase in sera of patients with vasculitis is derived from blood vessels, probably from endothelial cells.

Expression of ?-amylase and other gibberellin-regulated genes in aleurone tissue of developing wheat grains

Aleurone tissue from freshly harvested immature wheat grains (Triticum aestivum L. cv. Sappo) which is normally unresponsive to gibberellic acid can be made responsive by subjecting the tissue to a pre-incubation treatment in a simple buffered medium prior to the addition of the growth substance. The effectiveness of this treatment is dependent on grain age, with grains less than 15-20 days post anthesis failing to become converted to a responsive state whilst tissue from grains older than this become increasingly susceptible. Tissue from grains of a certain age (approx. 25-28 days post anthesis) produce small amounts of α-amylase following this treatment even in the absence of exogenously applied growth substance. Using different (32)-labelled complementary-DNA probes for α-amylase in wheat it was demonstrated that the failure of freshly harvested tissue to produce α-amylase was correlated with the absence of the appropriate mRNA species. Inability to accumulate α-amylase mRNA in response to gibberellic acid was removed by the pre-iccubation treatment and also by enforced drying. The gibberellin-regulated expression of other unidentified genes also responds to pre-incubation or drying. Induction of gibberellin-responsiveness in immature aleurone cells did not extend to the secretion of acid phosphatase, protease and ribonuclease.

Supplementary material to Acid ribonuclease from the insect C. capitata

European Journal of BiochemistryVolume 158, Issue 2 p. 370-372 Free Access Supplementary material to Acid ribonuclease from the insect C. capitata Juan M. GARCÍA-SEGURA, Juan M. GARCÍA-SEGURASearch for more papers by this authorM. Mar OROZCO, M. Mar OROZCOSearch for more papers by this authorJesús M. FOMINAYA, Jesús M. FOMINAYASearch for more papers by this authorJosé G. GAVILANES, José G. GAVILANESSearch for more papers by this author Juan M. GARCÍA-SEGURA, Juan M. GARCÍA-SEGURASearch for more papers by this authorM. Mar OROZCO, M. Mar OROZCOSearch for more papers by this authorJesús M. FOMINAYA, Jesús M. FOMINAYASearch for more papers by this authorJosé G. GAVILANES, José G. GAVILANESSearch for more papers by this author First published: July 1986 https://doi.org/10.1111/j.1432-1033.1986.tb09761.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume158, Issue2July 1986Pages 370-372 RelatedInformation

Purification, molecular and enzymic characterization of an acid RNase from the insect Ceratitis capitata.

An acid ribonuclease has been purified from the insect Ceratitis capitata. The specific activity of the purified enzyme is 580 units/mg. This enzyme is a single polypeptide chain of about 35.5 kDa, containing only one disulfide bridge and no free -SH groups. The A0.1%1cm at 280 nm is 1.90. The hydrodynamic radius of the native enzyme is 2.5 nm. The secondary structure of this RNase is composed of 10% alpha-helix, 31% beta-structure and 59% aperiodic conformation with an average number of residues per helical segment of 10, based on circular dichroic measurements. Optimum parameters for the enzyme activity are pH 5.5, 0.15 M ionic strength and 40 degrees C. Divalent cations are not required for the enzymic catalysis. This enzyme has been characterized as cyclizing endoribonuclease.

Biochemical lesions in liver and kidney after caecal amoebiasis in rats byEntamoeba histolytica and their reversal by antiamoebic drugs

Levels of lipid peroxides in rat caecum, blood, liver and kidney and the capacity of tissue homogenates to form lipid peroxidesin vitro was enhanced after caecal amoebiasis in rats produced byEntamoeba histolytica (IB-1). The activity of hepatic drug-metabolizing enzymes in post-mitochondrial fraction and the cytochrome P450 contents in microsomal fraction decreased significantly, while lysosomal enzymes such as acid phosphatase, acid ribonuclease and cathepsin B showed an increase in the liver homogenates of infected animals. These changes were reversed following treatment with the antiamoebic drug, metronidazole

Identification of the glutamyl and histidyl residues involved in the active site of a minor ribonuclease from Aspergillus saitoi.

A glutamyl and two histidyl residues that are suspected to be part of the active site of a base non-specific, guanine-preferential ribonuclease from Aspergillus saitoi (RNase Ms) were located.RNase Ms modified by radioactive iodoacetate was digested by α-chymotrypsin, then separated by paper chromatography and paper electrophoresis. The amino acid composition of the radioactive peptide indicated that the site of the modification was Glu57.A simple procedure to separate three histidyl-residue-containing peptides from RNase Ms was established. The procedure was used on the photooxidized RNase Ms, and the photooxidized histidyl residues were found to be His39 and His91.

The lysosomal distribution of cathepsin B in the rat kidney cortex.

Subcellular distribution of cathepsin B following subfractionation of the kidney cortex mitochondrial/lysosomal fraction by rate sedimentation indicates that this enzyme is mainly associated with the large, fast sedimenting lysosomes (protein droplets). A small proportion of cathepsin B is also present in the small lysosomes which cosediment with mitochondria, peroxisomes, and brush border and other large membrane vesicles. Amongst this broad spectrum of small lysosomes the distribution of cathepsin B, together with other acid hydrolases is associated with the more rapidly sedimenting lysosomes whilst cathepsin D differs in being associated with the slowest sedimenting lysosomes. Equilibrium banding in sucrose gradients shows the large lysosomes band at a density of 1.235 g/ml and that the small lysosomes have two distinct populations at densities 1.20 and 1.235 g/ml. Cathepsin B (and also cathepsin D and acid ribonuclease) appears to be associated only with lysosomes of high density. The various other acid hydrolases assayed are found in all the lysosomal populations. Small and large lysosomes of high density are very rich in a number of proteinases and therefore most probably represent lysosomal populations involved in the catabolism of proteins taken up from the glomerular filtrate.

Ribonuclease from cytosolic fraction of human erythrocytes

Ribonuclease (RNase) activity is detectable in only one third of specimens of human erythrocyte haemolysates. On the other hand, treatment of erythrocytic cytosoles with sulphosalicylic acid reveals an inhibitor-bound RNase activity which is present in all erythrocyte specimens studied. The level of the erythrocyte inhibitor-bound RNase activity is comparable to that in human lymphocytes. Isolated RNase from the cytosolic fraction of human erythrocytes is poly-C avid RNase with maximum activity at pH 6.5. The enzyme is resistant to treatment with strong acids and heating up to 95°C. Molecular filtration of the erythrocyte RNase shows that it is composed of two fractions differing in molecular mass, 19 000 and 15 000. No difference in enzymic properties between these fractions was found. The general properties of erythrocyte cytosolic RNase are much like those of acid RNases of human granulocytes and lymphocytes. As the erythrocytes do not metabolize RNA no function for the inhibitor-bound RNase can be suggested. Assuming that the observed erythrocyte RNase is the residual enzyme, persisting in the cell since it was functioning in the nucleated erythrocyte precursors, one may surmise that levels of free and inhibitor-bound erythrocyte RNase activity may be related to the normality or abnormality of erythrocyte maturation.

Three-dimensional structure of the ribonuclease t 1 · 3'-guanylic acid complex at 2.6 Å resolution

The mother enzyme of RNase T 1 was co-crystallized with its natural product, 3'-GMP at pH 4.0. The X-ray structure of this complex was refined with 2432 reflections in the 5.4-2.6 Å range using a stereochemical restrained method (conventional R = 27.4%). The overall polypeptide chain folding is very similar in the secondary structure elements to the RNase T 1 in the complex with 2'-GMP crystallized also at pH 4.0, but larger conformational changes occur in the loop regions. The base recognition scheme is identical in both complexes but in RNase T 1 · 3'-GMP, the ribose phosphate is not seen in the electron density, probably due to static disorder. X-ray crystallography Ribonuclease T 1 3'-Guanylic acid Ribonuclease T 1 · 3'guanylic acid complex Specific recogniton Disordered ribose

The modification of tyrosyl residues of a minor ribonuclease from Aspergillus saitoi.

The role of tyrosyl residues in the enzymatic activity and the state of tyrosyl residues of guanine preferential ribonuclease (RNase Ms) from Aspergillus saitoi were studied. 1) The solvent perturbation difference spectra of RNase Ms measured with ethylene glycol and polyethylene glycol as perturbants indicated that ca. 5 tyrosyl residues and one tryptophan residue were exposed to solvents. 2) The spectrophotometric titration of RNase Ms indicated that ca. 5 tyrosyl residues were titrated first, giving an apparent pKa value of 10.5, and the rest of the tyrosine residues gave higher pKa values. 3) About 8 tyrosine residues in RNase Ms were acetylated by excess N-acetylimidazole and about 6 of them were reactive towards a relatively low concentration of the reagent. Extrapolation of the curve showing the relation between the tyrosyl residues modified and the remaining activity indicated that the enzyme was inactivated when 4-5 tyrosyl residues were modified. 4) The chemical modification of RNase Ms with diazonium 1 (H)-tetrazole was also studied. The plot of the relationship between the residual activity and the tyrosyl residues modified showed that 1-1.5 tyrosyl residue (s) was responsible for the loss in enzymatic activity. 5) The enzymatic activities of RNase Ms modified by the two kinds of tyrosine-modifying reagents were measured with ribonucleic acid (RNA) and guanyl (3'→5') cytidine (GpC) as substrates at pH 5.0. The loss in enzymatic activity was more marked when RNA was used as a substrate than with GpC as a substrate. 6) Based on the reported (Heinemann and Saenger, Nature, 299, 27 (1982)) three-dimensional structure of RNase T1, which is about 60% sequence-homologous with RNase Ms, the possible site of the diazotization is discussed.

Acid hydrolases during Artemia development: A role in yolk degradation

1. 1. A broad group of acid hydrolytic activities have been determined during Artemia development including cathepsin B acid ribonuclease, acid deoxyribonuclease, acid phosphatase, acid phosphodiesterase, β-glucosidase, β- N-acetylgalactosaminidase and acid lipase. These enzymes present maximum activity in nauplii, when yolk degradation is maximum. 2. 2. Artemia cathepsin B proteinase is able to degrade lipovitellin in vitro with a pattern similar to that found in vivo. These results suggest the involvement of acid hydrolases in the degradation of yolk. 3. 3. In cryptobiotic embryos, acid hydrolases were found associated with structures of buoyant density 1.18. The structures appeared at the electron microscope as 0.4 μm dia. vesicles when revealed by acid phosphatase cytochemistry.

Latency differences of lysosomal enzymes in cardiac and skeletal muscles of male and female mice

1. 1. The purpose of this study was to compare the latencies of lysosomal enzymes (β-glucuronidase, β- N-acetylglucosaminidase, arylsulphatase and acid ribonuclease) in heart and in red and white skeletal muscle of male and female mice ( Mus musculus). The unsedimentable, free activities together with releasable (Triton X-100, hypotonie shock and freeze-thawing treatments) and unreieasable, bound activities were assayed. 2. 2. The distribution of acid hydrolases to different fractions was strikingly heterogeneous. The most distinct differences occurred between the distributions of β-glucuronidase and β- N-acetylglucosaminidase. 3. 3. The differences between muscle types occurred in the activity levels of lysosomal enzymes, rather than in the fractional distributions. 4. 4. Sex-related differences were small and occurred mainly in the activity levels of heart muscle (higher in female mice). 5. 5. The results suggest that the heterogeneous distribution of lysosomaS enzymes originates in the compartimentai differences of lysosomal enzymes in muscle cells, rather than the differences in cell populations of different muscle types.

The breakdown of Tetrahymena ribosomes by lysosomal enzymes: Inhibition by cytosol

1. 1. Extracts from Tetrahymena lysosomes contained acid RNase and proteinase. At pH 7.4 there was appreciable proteinase activity which was inhibited by a heat-stable protein present in cell sap. 2. 2. Lysosomal enzymes rapidly converted 80S ribosomes to subunits at pH 7.4. Hydrolysis of ribosomal RNA was very slow at pH 7.4 but rapid at pH 5.0. 3. 3. These reactions were inhibited by proteinase inhibitors and by cell sap, but the latter was relatively ineffective at pH 5.0. 4. 4. It seems unlikely that ribosome breakdown in vivo is initiated by the release of lysosomal enzymes into the cytosol.

The activities of ribosome-degrading enzymes and of a proteinase inhibitor in Tetrahymena pyriformis during starvation

1. 1. In starved Tetrahymena acid RNase decreased but acid proteinase and a heat-stable proteinase inhibitor both increased. 2. 2. A greater proportion of proteinase than RNase was released from the lysosomes of growing cells by homogenization, but progressively less proteinase was released during starvation. 3. 3. Inhibitors of protein synthesis enhanced the decrease in RNase and prevented the increase in proteinase and proteinase inhibitor. Chloroquine caused a large increase in both enzymes. 4. 4. Proteinase and RNase may be located in different lysosomes which together participate in ribosome destruction, but this process is unlikely to be limited by the total amount of these lysosomal hydrolases.

Purification and properties of three cytosolic ribonucleases of mouse liver.

The ribonucleolytic activity of mouse liver cytosol is due to at least three different enzymes, whose purification is reported. Two of these enzymes, an alkaline and a neutral RNase, have specificities practically identical with that of pancreatic RNase. The third enzyme, an acid RNase, is highly specific for NpU bonds where N is A, G or C and also cleaves ApG bonds provided they are part of a GpApG sequence and preferentially a GpApGpA repeat.

Effects of T-2 toxin on glucose and tryptophan uptake and intestinal mucosal enzymes

We studied the uptake of d-glucose and l-tryptophan by the small intestine and estimated the activities of the intestinal brush border enzymes (sucrase, lactase, Na +-K +-ATPase and alkaline phosphatase) and lysosomal enzymes in rats receiving T-2 toxin orally. Considerable decrease occurred in glucose and tryptophan uptake and in brush border sucrase, lactase and (Na + - K +)-ATPase. Alkaline phosphatase activity and release of lysosomal enzymes (acid phosphatase and acid ribonuclease) was unchanged.

Purification of chicken liver ribonucleases by affinity chromatography with UMP-Sepharose (nucleosides and nucleotides. LII).

A procedure for the preparation of chicken liver ribonucleases (RNases) is described, involving affinity chromatography on Sepharose coupled with 5'-amino-5'-deoxyuridine 2'(3')-phosphate. Two kinds of RNases having acidic pH optima were obtained. One RNase exhibited preferential nucleolytic activity toward poly C rather than poly U and the other was specific for poly U. The former RNase may be identical to that reported by Levy et al. and the latter resembles acid RNase detected in several mammalian tissues.

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.

Effects of Chrysotile on a Lysosomal Enzyme Preparation and on the Hydrolytic Enzyme Activity of Cultured Alveolar Macrophages

The interaction between chrysotile and three lysosomal enzymes (acid phosphatase, acid RNase and acid protease) in isolated lysosomal enzyme-rich preparations (LEP), from sheep alveolar macrophages maintained in the presence and absence of serum components or pulmonary surfactant at pH 5.0 and pH 7.0 for up to 22 days, is investigated. It is concluded that chrysotile does not inhibit or enhance lysosomal enzyme activity at either pH but may preferentially absorb specific enzymes and that the binding reaction between any given enzyme and mineral can be dependent on the presence of other organic compounds. The release of three hydrolytic enzymes (beta-galactosidase, acid RNase and protease) from cultured rabbit alveolar macrophages, in the presence of different concentrations of bovine serum (5-20%) and in the presence and absence of chrysotile for 72 hr, was also studied. Chrysotile enhances early differential release of each hydrolytic enzyme, but after 72 hr both control and chrysotile-treated cultures (maintained in 10-20% serum) have very similar intra- and extracellular levels of hydrolytic activity. The apparent differential release of lysosomal enzymes by untreated macrophages, which is dependent on serum concentration and time in vitro, is discussed.