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

---

Query: EC:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated nuclei incubated with [14C]protein hydrolysate are shown to incorporate labelled amino acids into the acid-insoluble fraction. Purified chromatin and the complex of DNA with firmly bound proteins possess similar ability. The optimum pH of the reaction is 6.5-7.0, 2 mM MgCl2 stimulates incorporation, the temperature optimum is 37-40 degrees C. Chloramphenicol depresses incorporation by 70%, puromycin by 40%, cycloheximide does not affect the chromatin activity. Incorporation does not depend on the presence of ATP or GTP, and is substantially inhibited by deoxyribonuclease but not by ribonuclease treatment of chromatin or of the nuclei. Specific activity of firmly bound chromatin non-histone proteins is higher than that of labile bound ones; histones are not labelled. After pronase treatment of proteins radioactivity changes to an acid-soluble state. The molecular weight of isolated labelled polypeptides is about 6000 as shown by gel filtration and the analysis of NH2-terminal amino acids. Labelled polypeptides firmly bound to DNA consist of 7-10 amino acids. Specific activity of proteins firmly bound to DNA increases linearly with the time of incubation of chromatin with [14C]protein hydrolysate, the activity curve of labile bound non-histone proteins has a distinct sygmoid character. The polypeptide-synthesizing activity of rat liver chromatin increases between 9 h and 21 h after partial hepatectomy. Irradiation with 800 rads 30 min before the operation prevents activation of amino acid incorporation. From nine amino acids studied alanine, methionine, lysine, tyrosine and arginine are not incorporated in the system described. Glutamic acid is polymerized most effectively. Glutamine, asparagine and glycine are incorporated 7-8 times less. The data are given indicating that the incorporation is not random when an amino acid mixture is present. Preincubation of chromatin with NAD+ but not with its analogues increases the polypeptide-synthesizing activity of chromatin. The activation is prevented by thymidine and nicotinamide. Storage (18 h at 2-4 degrees C) brings about a complete loss of the polypeptide-synthesizing activity of chromatin. The ability of 'old' chromatin to incorporate amino acids can be restored by preincubating it with NAD+. Storage of chromatin in the presence of 5 mM adenosine 3',5'-monophosphate (cAMP) does not result in decrease of the polypeptide-synthesizing activity. It is assumed that poly-(ADP-ribose) is the energy source for amino acid activation in the system described.
...
PMID:Polypeptide-synthesizing activity of eukaryotic chromatin. Properties, dependence on poly(ADP-ribose) and connection with the cell cycle. 737 37

The crystal structure of purine-specific ribonuclease (RNase) U2 from Ustilago sphaerogena has been solved by the molecular replacement methods using RNase T1 as a search model. The structure, with 114 amino acid residues, 141 water molecules, and a sulfate ion, is refined to an R factor of 0.143 at 1.8 A resolution. As evidenced by the electron densities, residues 49 and 50 are revised to Glu 49 and Asp 50, respectively, and also Asp 45 is identified as a beta-isomerized form to L-isoaspartate with a beta-peptide linkage. RNase U2 consists of a beta-hairpin at residues from 7 to 14, a 4.4-turn alpha-helix from 16 to 32, a central beta-sheet with five strands, and a protruding beta-turn from 74 to 77. As for the catalytic site residues, His 41, Glu 62, and Arg 85 are located as constituents of the central beta-sheet, and Tyr 39 and His 101 are situated at either end of the beta-sheet. The side chains of Tyr 39, Glu 62, Arg 85, and His 101 are hydrogen-bonded to the sulfate ion which marks the RNA phosphate position. Though the side chain of His 41 is pointing away from the sulfate, small conformational adjustments of His 41 enable the side chain to interact with either the phosphate or the ribose group of RNA. The loop region from Tyr 44 to Asp 50 is ascribed to the base recognition site where Glu 49 is involved in adenine recognition. beta-Isomerized Asp 45 suggests that this region is conformationally flexible and alterable.
...
PMID:Crystal structure of Ustilago sphaerogena ribonuclease U2 at 1.8 A resolution. 749 61

Peptide-water interactions of a ribonuclease C-peptide analogue, RN-24 (Suc-AETAAAKFLRAHANH2), which exhibits significant helicity, have been studied in solution using homonuclear 2D and 3D NMR cross-relaxation experiments. Dipolar peptide proton-water proton interactions are indicated by a large number of NOESY-type cross peaks at the H2O resonance frequency, most of them with opposite sign relative to the diagonal. Some cross peaks arise from intrapeptide cross relaxation to labile protons of histidine, threonine, lysine and arginine side chains. The observed peptide-water interactions are rather uniformly distributed, involving peptide backbone and side chains equally. The data are consistent with rapid fluctuations of the conformational ensemble and the absence of peptide regions that are highly shielded from bulk solvent, even in a peptide that exhibits high propensities for formation of helical secondary structure.
...
PMID:Hydration of the partially folded peptide RN-24 studied by multidimensional NMR. 764 54

Eosinophil cationic protein (ECP) is a toxin secreted by activated human eosinophils that has anti-parasitic, antibacterial, and neurotoxic activities; ECP also has ribonuclease activity and structural homology to other mammalian ribonucleases. To determine the relationship between the ribonuclease activity and cytotoxicity of ECP, a method for producing recombinant ECP (rECP) in a prokaryotic expression system was devised. Periplasmic isolates from induced bacterial transfectants contained enzymatically active rECP; micromolar concentrations of rECP were shown to be toxic for Staphylococcus aureus (strain 502A). In contrast, recombinant eosinophil-derived neurotoxin, with 67% amino acid sequence identity to ECP, had little to no toxicity for S. aureus; these findings are analogous to those obtained with purified, granule-derived ECP and eosinophil-derived neurotoxin. Two single base pair mutations were introduced into the coding sequence of rECP (Lys38 to Arg and His128 to Asp) to convert ribonuclease active-site residues into non-functional counterparts. These mutations eliminated the ribonuclease activity of rECP but had no discernible effect on the antibacterial activity of this protein, demonstrating that ribonuclease activity and cytotoxicity are, in this case, independent functions of ECP.
...
PMID:Recombinant human eosinophil cationic protein. Ribonuclease activity is not essential for cytotoxicity. 771 81

All of the individual carboxyl groups (the side-chain carboxyl groups of Asp and Glu, and the C-terminal alpha-carboxyl group) in Escherichia coli ribonuclease HI, which is an enzyme that cleaves the RNA strand of a RNA/DNA hybrid, were pH-titrated, and their ionization constants (pKa) were determined from an analysis of the pH-dependent chemical shifts of the carboxyl carbon resonances obtained from 1H-13C heteronuclear two-dimensional NMR. The pKa values in the enzyme varied widely among individual residues, for example, in the unusual pKa values for two important catalytic residues, Asp10 (pKa 6.1) and Asp70 (pKa 2.6). Moreover, remarkable two-step titrations were observed for these carboxylates. The binding of Mg2+ ion to the enzyme, which is the cofactor necessary for catalytic activity, caused no significant change in the pKa values of the carboxyl groups, except for that of Asp10. The variations of the pKas that were dependent on the microenvironment in the protein were theoretically reproduced to compare with the experimental results by a numerical calculation, using a continuum electrostatic model. Most of the significant pKa decreases were brought about through strong electrostatic interactions with the neighboring basic amino acids, Arg or Lys. The pKa shifts and the two-step titrations of Asp10 and -70, which are close to each other, were interpreted to be due to the neighboring effect of two functional groups, as observed in the interacting titratable groups of a dicarboxyl compound or in the active site carboxylates of lysozyme and aspartic protease. The role of Asp10 in the catalytic action is either to be the proton donor to the RNA moiety or the binding partner of the Mg2+ ion cofactor. Asp70, on the other hand, is considered to be the proton acceptor from a water molecule.
...
PMID:Individual ionization constants of all the carboxyl groups in ribonuclease HI from Escherichia coli determined by NMR. 790 91

A ribonuclease (RNase) that cleaves specifically on the 3' side of uridine [Shapiro, R., Fett, J. W., Strydom, D. J. & Vallee, B. L. (1986a) Biochemistry 25, 7255-7264] was purified from human plasma and its amino acid sequence was determined. This protein is a 119-residue single-chain polypeptide cross-linked by four disulfide bonds and has an amino-terminal pyroglutaminyl residue. No post-translational modifications were observed during extensive sequence studies on peptide fragments, except for the amino-terminal pyroglutamic acid and a possible deamidation of Asn66. The protein is homologous to the pancreatic ribonucleases and angiogenin, but differs substantially from both of these proteins; the protein sequence has 43% identity with human pancreatic ribonuclease and 39% identity with human angiogenin, as compared to 35% identity between human angiogenin and pancreatic ribonuclease. It is referred to as RNase 4, based on the nomenclature currently used for the genes of pancreatic RNase (RNase 1) and the eosinophil-derived RNases (RNase 2 and RNase 3). Virtually all of the RNase active-site components, including the catalytic residues His12, His119 and Lys41, are preserved. However, some invariant residues of RNase 1 are replaced, e.g. Lys7 by arginine, Asp14 by histidine, and Pro42 by arginine. RNase 4 contains a unique two-residue deletion at the position corresponding to amino acids 77 and 78 of pancreatic RNase, and its carboxyterminal sequence is truncated at position 122. The deletion in angiogenin at position 21 is also found in RNase 4. RNase 4 is very similar to two RNases isolated from bovine and porcine liver, and together they form a new family in the RNase superfamily. The degree of inter-species similarity (90%) is much greater than within the pancreatic RNase and angiogenin families, which suggests that this ribonuclease could possess a physiologically important function other than general RNA catabolism.
...
PMID:The amino acid sequence of human ribonuclease 4, a highly conserved ribonuclease that cleaves specifically on the 3' side of uridine. 822 79

Complete primary structure of an extracellular low molecular mass ribonuclease of Bacillus thuringiensis was determined using Edman degradation and mass-spectrometry analysis of individual peptides obtained after hydrolysis of the protein by cyanogen bromide and staphylococcal protease. The peptides were isolated and purified by HPLC and denaturing PAGE. The enzyme consists of 109 amino acid residues (Asp 8, Asn 6, Thr 6, Ser 10, Glu 3, Gln 1, Pro 3, Gly 9, Ala 12, Val 7, Ile 7, Leu 7, Tyr 7, Phe 4, His 1, Arg 10, Trp 3 and Lys 5) and has a molecular weight of 12182 Da. A single difference was detected between primary structures of the enzyme and an extracellular ribonuclease of B. intermedius.
...
PMID:[Complete primary structure of Bacillus thuringiensis extracellular ribonuclease]. 825 Sep 78

Androgen insensitivity is an X-linked disorder of sexual differentiation resulting from mutations in the androgen receptor (AR) gene. In this paper, we report the clinical phenotype and molecular analysis of two siblings with severe partial androgen insensitivity due to a novel mutation in the ligand-binding domain of the AR gene. Binding studies using cultured genital skin fibroblasts demonstrated reduced AR affinity and binding capacity. Nucleotide sequence analysis of the AR gene of both siblings revealed a point mutation causing a glycine to arginine amino acid substitution at position 907 within a conserved region of the ligand-binding domain. A silent guanine to adenine substitution was also identified in the protein-coding region of exon 1. Using an expression vector in which the identified mutation was recreated by site-directed mutagenesis, the mutant receptor was found to have a reduced binding affinity (Kd = 3.06 nmol/L) for mibolerone compared with that of normal AR (Kd = 1.71 nmol/L) when expressed in COS-7 cells. In cotransfection experiments using CV-1 cells and a mouse mammary tumor virus-chloramphenicol acetyltransferase reporter system, the concentration of dihydrotestosterone required to induce half-maximal chloramphenicol acetyltransferase gene expression was 50-fold higher in cells transfected with the mutant AR complementary DNA than in cells transfected with normal AR complementary DNA. AR messenger ribonucleic acid levels in genital skin fibroblasts determined by both competitive PCR amplification and ribonuclease protection assay were decreased compared with normal values. Our studies demonstrate the importance of this region of the AR gene in normal AR function and AR gene expression.
...
PMID:Partial androgen insensitivity caused by an androgen receptor mutation at amino acid 907 (Gly-->Arg) that results in decreased ligand binding affinity and reduced androgen receptor messenger ribonucleic acid levels. 855 Jul 58

The rne gene of Escherichia coli encodes a 118 kDa protein that has ribonuclease E (RNase E) activity and binds RNA. A functional rne gene product is essential for cell viability and for the processing and/or decay of a variety of RNA species, including 9 S RNA, mRNA and RNAI, the antisense RNA regulator of ColE1-type plasmid replication. By testing the ability of different segments of the Rne protein to catalyze RNA cleavage and to bind RNA, we found that the N-terminal half (residues 1 to 498) of Rne contains a catalytic function sufficient for site-specific cleavage of oligoribonucleotides and complex RNAs. The C-terminal half of the protein, which contains both an arginine-rich region (residues 597 to 684) that we show binds RNA and a segment that is essential for cell viability (residues 844 to 1061), had no detectable endoribonucleolytic activity. Our results, which map the catalytic domain of RNase E, indicate the existence of discrete functional domains within the multifaceted Rne protein.
...
PMID:The N-terminal domain of the rne gene product has RNase E activity and is non-overlapping with the arginine-rich RNA-binding site. 856 79

We describe an 18-year-old with moderate hereditary spherocytosis. The condition was associated with a 35% decrease in band 3. The underlying mutation was Arg to stop at codon 150 (CGA-->TGA) and was designated R150X, which defined allele Lyon of the EPB3 gene. The inheritance pattern was dominant. However, the mother, who also carried the allele Lyon, had a milder clinical presentation and only a 16% decrease of band 3. We suggested that the father had transmitted a modifying mutation that remained silent in the heterozygous state. Nucleotide sequencing after single strand conformation polymorphism analysis of the band 3 cDNA and promoter region revealed a G-->A substitution at position 89 from the cap site in the 5'-untranslated region, designated 89G-->A, which defined allele Genas. A ribonuclease protection assay showed that (1) the allele Genas (father) resulted in a 33% decrease in the amount of band 3 mRNA, (2) the reduction caused by the allele Lyon (mother) was 42%, and (3) the compound heterozygous state for both alleles (proband) resulted in a 58% decrease. These results suggest that some mildly deleterious alleles of the EPB3 gene are compensated for by the normal allele in the heterozygous state. They are shown through the aggravation of the clinical picture, based on more obvious molecular alterations when they occur in trans to an allele causing a manifest reduction of band 3 membrane protein concentration.
...
PMID:Hereditary spherocytosis with band 3 deficiency. Association with a nonsense mutation of the band 3 gene (allele Lyon), and aggravation by a low-expression allele occurring in trans (allele Genas). 870 15


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---