Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A pyrimidine base-specific ribonuclease was purified from bullfrog (Rana catesbeiana) liver by means of CM-cellulose column chromatography and affinity chromatography on heparin-Sepharose CL-6B, which gave single band on SDS-slab electrophoresis. The primary structure of the bullfrog liver RNase was determined. It consisted of 111 amino acid residues, including 8 half-cystine residues. From the sequence, it was concluded that three disulfide bridges in RNase A were conserved in the bullfrog RNase, that a disulfide bridge in RNase A [Cys65-Cys126 (RNase A numbering)] was deleted, and that a new disulfide bridge was created in the C-terminal part of the enzyme. In this frog RNase, the amino acid residues thought to be essential for catalysis in bovine pancreatic RNase A were conserved except for Asp121 (RNase A numbering). The sequence homology of the bullfrog liver RNase with bovine pancreatic RNase A was 30.6%. The sequence of bullfrog liver RNase was very similar to those of lectins obtained from bullfrog egg by Titani et al. [Biochemistry (1988) 26, 2189-2194] and R. japonica egg by Kamiya et al. [Seikagaku (in Japanese) (1989) 60, 733; and personal communication from Kamiya, Y., Oyama, F., Oyama, R., Sakakibara, F., Nitta, K., Kawauchi, H., and Titani, K.]. The sequence homology between the bullfrog liver RNase and the two lectins was 70.2 and 64.8%, respectively.
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PMID:Primary structure of a ribonuclease from bullfrog (Rana catesbeiana) liver. 261 82

Beef liver membranes were shown to have different kinds of 3,5,3'-triiodo-L-thyronine binding proteins including the 55-kDa protein which had been reported to have this activity in many cells by affinity labelling with N-bromoacetyl-3,5,3'-[125I]triiodo-L-thyronine. In order to characterize the molecular features of these binding proteins, the 55-kDa protein was purified from a beef liver membrane fraction abundant in the plasma membrane. The protein was solubilized with 0.5% Chaps and purified by chromatography on gel filtration, hydroxyapatite, and Mono Q anion-exchange columns. The purity was confirmed with reversed-phase HPLC and SDS/PAGE. Consequently, 0.4% of the total proteins in the membrane fraction was recovered as the 55-kDa protein. One fourth of the amino acid composition of this protein was Glx (14.6%) plus Asx (11.7%) and the pI of this protein was 4.5. The purified protein has triiodothyronine-binding activity with a Kd of 57 nM which is similar to the high-affinity binding site of the membranes. The anti-(55-kDa protein) sera specifically recognized the 55-kDa protein of beef, rat and human cells. The immunoglobulin G fraction of the anti-(55-kDa protein) sera inhibited triiodothyronine binding to the beef liver membrane fraction. The purified protein also showed the activity of protein disulfide-isomerase (EC 5.3.4.1) as determined by reactivating scrambled ribonuclease. These data strongly suggested that the multi-functional 55-kDa protein which has triiodothyronine-binding activity and the activity of protein disulfide-isomerase, which is also reported to be the beta subunit of prolyl-4-hydroxylase, glycosylation-site-binding protein of oligosaccharyl transferase and iodothyronine 5'-monodeionidase, could be significant in the action of triiodothyronine towards the target cells.
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PMID:Purification and characterization of 55-kDa protein with 3,5,3'-triiodo-L-thyronine-binding activity and protein disulfide-isomerase activity from beef liver membrane. 277 49

Protein disulfide-isomerase was isolated as a homogeneous protein from 15-day-old chick embryos. The enzyme has a molecular weight of 56,000 in SDS-polyacrylamide gel electrophoresis. Its Km value for randomly cross-linked ribonuclease, a protein used as a substrate for the enzyme, was 0.3 microM, and the Km value for DTT was 1.0 microM. Its optimum pH was 7.5 and its optimum temperature, 33 degrees C. The maximal velocity of pure protein disulfide-isomerase from chick embryos under optimal conditions was about 29,000 units/g. Protein disulfide-isomerase was able to activate purified prolyl 4-hydroxylase 2- to 3-fold, the activation being higher for enzyme stored for a longer time. This activation is probably due to the repairing of disulfide exchanges occurring in the prolyl 4-hydroxylase structure during purification and storage. Prolyl 4-hydroxylase activity was very stable in microsomes, however, and protein disulfide-isomerase was unable to increase the microsomal prolyl 4-hydroxylase activity, suggesting that prolyl 4-hydroxylase retains its native conformation in microsomes. Protein disulfide-isomerase was able to reactivate prolyl 4-hydroxylase inactivated by mild H2O2 treatment. The activity obtained after this treatment and protein disulfide-isomerase incubation corresponded to the amount of prolyl 4-hydroxylase tetramer found after H2O2 treatment. The data suggest that protein disulfide-isomerase is able to activate only the tetramer part of the enzyme preparation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protein disulfide-isomerase retains procollagen prolyl 4-hydroxylase structure in its native conformation. 302 99

A soluble ATP/Mg2-dependent proteolytic system from rabbit cardiac muscle has been identified (m ca. 310 kDa) and purified ca. 9-fold. This enzyme which splits the substrate [3H]globin and 125I-bovine serum albumin (125I-BSA) has many similarities to the ATP-dependent proteolytic enzyme system from reticulocytes which utilizes ubiquitin: 1) The specific activities in reticulocyte lysates and cardiac muscle extracts are of the same magnitude (0.5-1 arb. unit/mg). 2) The binding and elution behavior on DEAE-cellulose is similar. 3) In both cases the pH optimum (substrate 125I-BSA) is pH 7.6. 4) Both enzymes are inhibited by hemin, NEM and iodoacetate but not e.g. by leupeptin, or inhibitors of serine proteases. 5) Neither enzyme system can utilize ATP-analogs such as AMP-CPP, AMP-PCP, AMP-PNP or ATP-gamma-S. There are however also significant differences: 1) The enzyme system from cardiac muscle is fully active in the absence of ubiquitin and cannot be activated by this peptide. 2) The enzyme from cardiac muscle can degrade methylated BSA. 3) The cardiac muscle enzyme can be further purified on Sepharose 4B; the enzyme from reticulocytes is inactivated by this procedure. 4) The cardiac enzyme cannot be inactivated by ribonuclease as the reticulocyte counterpart. Although ubiquitin does not appear to play a role in the isolated ATP/Mg2-dependent proteolytic system from cardiac muscle, it is demonstrated for the first time that 125I-ubiquitin can be conjugated to a wide variety of cardiac muscle proteins in vitro in an ATP-dependent manner. Apparent molecular masses of major conjugates were: 185 kDa, 140 kDa, 85 kDa, 65 kDa, 46 kDa, 38 kDa and 36 kDa as estimated by discontinuous SDS gel electrophoresis. Addition of purified phosphorylase kinase to cardiac muscle extract changed the ubiquitination pattern by the appearance of two novel protein bands. It is concluded that the ATP/Mg2-dependent proteolytic system of cardiac muscle must be differentiated from the proteolytic system of reticulocytes mainly because of its ubiquitin-independence. Nevertheless the conjugation of 125I-ubiquitin to many muscle proteins is a strong indication for a crucial role of this interesting peptide in striated muscle.
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PMID:ATP-dependent proteolysis and the role of ubiquitin in rabbit cardiac muscle. 304 36

The major secretory ribonuclease (RNase) of human urine (RNase HUA) was isolated and sequenced by automatic Edman degradation and analysis of peptides and glycopeptides. The isolated enzyme was shown to be free of other urine RNase activities by SDS/polyacrylamide-gel electrophoresis and activity staining. It is a glycoprotein 128 amino acids long, differing from human pancreatic RNase in the presence of an additional threonine residue at the C-terminus. It differs from the pancreatic enzyme in its glycosylation pattern as well, and contains about 45 sugar residues. Each of the three Asn-Xaa-Ser/Thr sequences (Asn-34, Asn-76, Asn-88) is glycosylated with a complex-type oligosaccharide chain. Glycosylation at Asn-88 has not been observed previously in mammalian secretory RNases. Preliminary sequence data on the major RNase of human seminal plasma have revealed no difference between it and the major urinary enzyme; their similarities include the presence of threonine at the C-terminus. The glycosylation pattern of human seminal RNase is very similar to that of the pancreatic enzyme. The structural differences between the secretory RNases from human pancreas, urine and seminal plasma must originate from organ-specific post-translational modifications of the one primary gene product. Detailed characterization of peptides and the results of gel filtration of tryptic and tryptic/chymotryptic digests of performic acid-oxidized RNase have been deposited as Supplementary Publication SUP 50146 (4 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1988) 249, 5.
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PMID:Differences in glycosylation pattern of human secretory ribonucleases. 320 29

A ribonuclease (RNAase) was isolated and purified from the urine of a 45-year-old man by column chromatographies on DEAE-Sepharose CL-6B, cellulose phosphate and CM-cellulose followed by gel filtrations on Bio-Gel P-100 and Sephadex G-75, and finally to a homogeneous state by SDS-polyacrylamide gel electrophoresis. The enzyme was designated RNAase 1. It was possible to detect RNAase 1 isozymes in urine and serum without difficulty using isoelectric focusing electrophoresis followed by immunoblotting with a rabbit antibody specific to RNAase 1. The existence of genetic polymorphism of RNAase 1 was detected in human serum utilizing this technique (Yasuda, T. et al. (1988) Am. J. Hum. Genet., in press). RNAase 1 in serum and urine seemed to exist in multiple forms with regard to molecular weight and pI value. Genetically polymorphic RNAase 1 was a glycoprotein, containing three mannose, one fucose, four glucosamine and no sialic acid residues per molecule, with a molecular weight of 16,000 and 17,500 determined by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively. The enzyme was most active at pH 7.0 on yeast RNA substrate and inhibited remarkably by Cu2+, Hg2+ and Zn2+. It also showed definite substrate preference for poly(C) and poly(U), but much less activity against poly(A) and poly(G). Thus, the enzyme is a pyrimidine-specific RNAase.
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PMID:Purification and characterization of a human urine ribonuclease (RNAase 1) showing genetic polymorphism. 336 53

The brain ribonucleases of rabbit, guinea pig, rat, mouse and gerbil were investigated by histochemical and biochemical methods. For the localization, the ribonucleases were electrophoretically transferred from cryostat sections to polyacrylamide gels. Elevated ribonuclease activities were found in the cortex, the basal ganglia, the hippocampal formation and the ventricles, whereas the corpus callosum and the internal capsule exhibited lower activities. The total RNA degrading activities of the brain extracts of the different species varied in a wide range. However, a pre-requisite for the measurement of acid soluble degradation products in the test system was the inactivation of endogeneous ribonuclease inhibitors, present in all extracts. Molecular weight analysis by means of SDS-polyacrylamide gel electrophoresis revealed a characteristic set of ribonucleases for each species, consisting of enzymes with different pH-optima.
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PMID:Comparison of brain ribonucleases of rabbit, guinea pig, rat, mouse and gerbil. 336 57

A ribonuclease was isolated and purified to homogeneity from cobra venom. The enzyme was found to be homogeneous on SDS and non-SDS polyacrylamide gel electrophoreses, and high performance liquid chromatography. The purified enzyme hydrolysed poly(rC), but not poly(rA), poly(rU), poly(rG), poly(rI), or poly(rI).poly(rC). The presence of magnesium was found to be an essential requirement for the nucleolytic activity of this enzyme.
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PMID:A new ribonuclease from cobra venom (Naja naja) showing specificity towards cytidylic acid. 359 67

An intracellular effect of nickel(II) which may be involved in its carcinogenic action is the alteration of normal DNA-protein binding. This effect of ionic nickel was studied in Chinese hamster ovary cells using several chromatin isolation methods in combination with SDS-polyacrylamide gel electrophoresis. DNA from cells incubated with (35S)-methionine or (35S)-cysteine to radiolabel protein was prepared by three methods: (solation of nuclei or nucleoids followed by chloroform-isoamyl alcohol (24:1 v/v) extraction and in some cases an additional extraction in the absence or presence of 2M NaCl, 40 mM EDTA or SDS; by isopycnic centrifugation through Cs2SO4 gradients containing 0.8% sarkosyl, 2.2 MCs2SO4, 1 mM NaCl and 10 mM EDTA; or by chromatin disaggregation and denaturation using 9 M urea, 2% 2-mercaptoethanol, 4% Nonidet P-40 +/- 2 M NaCl. DNA from nickel-treated cells consistently had more (35S)-methionine radioactivity associated with it than did DNA from untreated cells. This radioactivity was resistant to ribonuclease but sensitive to protease. Differential extraction using denaturing agents and high ionic strength followed by SDS-polyacrylamide gel electrophoresis revealed that most of the tightly bound proteins were nonhistone chromosomal proteins, and possibly histone 1. The enhancement of DNA-protein binding from nickel-treated cells was disrupted by SDS, suggesting that nickel ions do not function as classical bifunctional crosslinking agents. Since regulation of DNA replication and gene expression is dependent upon DNA-protein interactions, the effect of nickel in altering the extent of DNA-protein binding may interfere with this regulation and may contribute to the carcinogenic activity of nickel compounds.
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PMID:Effects of nickel(II) on nuclear protein binding to DNA in intact mammalian cells. 362 Nov 37

A protein was isolated from plasma of partially (70%) hepatectomized rats that, injected in mice, increases the uptake of [3H]thymidine by liver DNA by 200-300% over that by injected control saline. The purification procedure consists essentially of three chromatography steps, employing Sephadex G-75, DEAE-cellulose and hydroxyapatite. The hepatic promoter (HP) preparation shows a single band in SDS/polyacrylamide (15%)-gel electrophoresis (silver stained), with an Mr of 64 000; its activity is suppressed by trypsin or pepsin and is unaffected by deoxyribonuclease or ribonuclease. On injection into mice (150 ng/mouse), it increases the mitotic index of the liver. It shows organ-specificity, acting on liver but not on spleen, kidney, lung or brain. In primary liver cultures, it produces an increase in uptake of [3H]thymidine into DNA in the range 1-10 ng/ml. In this system in vitro, it increases the uptake of 22Na+ immediately after addition.
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PMID:Purification of a liver DNA-synthesis promoter from plasma of partially hepatectomized rats. 374 89


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