Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sequence organization of the beta-globin mRNA precursor has been determined directly by analyzing the resistant fragments from the RNase A digestion of the precursor RNA-globin cDNA hybrid. Three fragments are obtained which proves that the beta-globin mRNA sequence in its precursor is split into three discontinuous segments. The two intervening sequences in the beta-globin gene are therefore transcribed and removed during mRNA maturation.
Nucleic Acids Res 1978 Sep
PMID:Sequence organization of the beta-globin mRNA precursor. 70 57

A heterobifunctional reagent, N-succinimidyl 3-(2-pyridyldithio)propionate, was synthesized. Its N-hydroxysuccinimide ester group reacts with amino groups and the 2-pyridyl disulphide structure reacts with aliphatic thiols. A new thiolation procedure for proteins is based on this reagent. The procedure involves two steps. First, 2-pyridyl disulphide structures are introduced into the protein by the reaction of some of its amino groups with the N-hydroxysuccinimide ester sie of the reagent. The protein-bound 2-pyridyl disulphide structures are then reduced with dithiothreitol. This reaction can be carried out without concomitant reduction of native disulphide bonds. The technique has been used for the introduction of thiol groups de novo into ribonuclease, gamma-globulin, alpha-amylase and horseradish peroxidase. N-Succinimidyl 3-(2-pyridyldithio)propionate can also be used for the preparation of protein-protein conjugates. This application is based on the fact that protein-2-pyridyl disulphide derivatives (formed from the reaction of non-thiol proteins with the reagent) react with thiol-containing proteins (with native thiols or thiolated by, for example, the method described above) via thiol-disulphide exchange to form disulphide-linked protein-protein conjugates. This conjugation technique has been used for the preparation of an alpha-amylase-urease, a ribonuclease-albumin and a peroxidase-rabbit anti-(human transferrin) antibody conjugate. The disulphide bridges between the protein molecules can easily be split by reduction or by thiol-disulphide exchange. Thus conjugation is reversible. This has been demonstrated by scission of the ribonuclease-albumin and the alpha-amylase-urease conjugate into their components with dithiothreitol. N-Succinimidyl 3-(2-pyridyldithio)propionate has been prepared in crystalline form, in which state (if protected against humidity) it is stable on storage at room temperature (23 degrees C).
Biochem J 1978 Sep 01
PMID:Protein thiolation and reversible protein-protein conjugation. N-Succinimidyl 3-(2-pyridyldithio)propionate, a new heterobifunctional reagent. 70 70

The dimethyl ester of bovine pancreatic ribonuclease-A (dimethyl RNAase-A), the initial product of esterification of RNAase-A in anhydrous methanolic HCl, was isolated in a homogeneous form. The two carboxy functions esterified in this derivative are those of glutamic acid-49 and aspartic acid-53. There were no changes in the u.v.-absorption spectral characteristics, the accessibility of the methionine residues, the resistance of the protein to proteolysis by trypsin and the antigenic behaviour of RNAase-A as a result of the esterification of these two carboxy groups. Dimethyl RNAase-A exhibited only 65% of the specific activity of RNAase-A, but still had the same K(m) value for both RNA and 2':3'-cyclic CMP. However, the V(max.) was decreased by about 35%. On careful hydrolysis of the methyl ester groups at pH9.5, dimethyl RNAase-A was converted back into RNAase-A. Limited proteolysis of dimethyl RNAase-A by subtilisin resulted in the formation of an active RNAase-S-type derivative, namely dimethyl RNAase-S, which was chromatographically distinct from dimethyl RNAase-A and had very nearly the same enzymic activity as dimethyl RNAase-A. Fractionation of dimethyl RNAase-S by trichloroacetic acid yielded dimethyl RNAase-S-protein and dimethyl RNAase-S-peptide, both of which were inactive by themselves but regenerated dimethyl RNAase-S when mixed together. Dimethyl RNAase-A-peptide was identical with RNAase-S-peptide. RNAase-S-protein could be generated from dimethyl RNAase-S-protein by careful hydrolysis of the methyl ester groups at pH9.5. The interaction of dimethyl RNAase-S-protein with RNAase-S-peptide appears to be about 4-fold weaker than that between the RNAase-S-protein and RNAase-S-peptide. Conceivably, the binding of the S-peptide ;tail' of dimethyl RNAase-A with the remainder of the molecule is similarly weaker than that in RNAase-A, and this brings about subtle changes in the geometrical orientation of the active-site amino acid residues of these modified methyl ester derivatives. It is suggested that these changes could be responsible for the generation of the catalytically less-efficient RNAase-A and RNAase-S molecules (dimethyl RNAase-A and dimethyl RNAase-S respectively).
Biochem J 1978 Sep 01
PMID:Structure and enzymic activity of ribonuclease-A esterified at glutamic acid-49 and aspartic acid-53. 70 73

Trypsin, pepsin and subtilisin have been used as conformational probes for the structure of bovine seminal ribonuclease BS-1 by studying, under definite conditions, their effects on the seminal enzyme, a dimeric protein made up to two identical subunits; on bovine pancreatic monomeric ribonuclease A (EC 3.1.4.22) with a polypeptide chain homologous to that of the seminal ribonuclease subunit chain; and on a monomeric, active and stable derivative of seminal ribonuclease. The results show: (1) that the C-terminal regions of the pancreatic and the seminal proteins are very similar as they appear to fit in an identical way to the active site of pepsin; (2) that the resistance of the N-terminal region of ribonuclease BS-1 to subtilisin is not due to the dimeric structure of the protein, but to the conformation of this region, where an essential feature is the presence of a proline residue at position 19; (3) that the monomer of ribonuclease BS-1 is resistant to tryptic action only when bound to the partner monomer in the quaternary structure of the protein. This indicates that dissociation of the seminal ribonuclease makes some potentially susceptible susceptible bond or bonds available to trypsin either through a conformational change of the protein subunit, or by simply exposing the protein area hidden at the intersubunit interfaces.
Biochim Biophys Acta 1976 Sep 14
PMID:Proteolytic enzymes as structural probes for ribonuclease BS-1. 78 46

tRNA3Met, one of the non-initiating methionine-specific tRNAs in brewer's yeast was purified from bulk tRNA labelled with [32P]phosphate by two column chromatographic steps. The primary structure of this tRNA was determined by the usual fingerprinting technique. Analyses of the isolated nucleotides and oligonucleotides from digests with pancreatic and T1 ribonucleases were in good agreement and stated that tRNA3Met consists of 76 nucleotide residues including 13 minor nucleotides. Overlaps from which the complete sequence could be deduced were derived from the analyses of 15 fragments obtained by partial digestion with T1 ribonuclease.
Eur J Biochem 1976 Sep
PMID:The primary structure of a non-initiating methionine-specific tRNA from brewer's yeast. 78 36

Mutants of Escherichia coli K12, deficient in up to three major outer membrane proteins b, c and d have been constructed. Mutants that lack the lipopolysaccharide sugar heptose are deficient in protein b. All heptose-deficient strains are supersensitive to lysozyme, various antibiotics and detergents. They excrete the periplasmic enzyme ribonuclease I. Mutants deficient in proteins c and/or d have the same sensitivity towards these compounds as the parent strain. Cells of single, double and triple mutants are all rod-shaped. Electrophoretic analysis of cell envelope proteins indicates that in some mutants the protein deficiency is partially compensated for by increased amounts of one or two of the other major outer membrane proteins. Heptose-deficient strains have an increased amount of 2-keto-3-deoxyoctonate.
Mol Gen Genet 1976 Sep 23
PMID:Heptose-deficient mutants of Escherichia coli K12 deficient in up to three major outer membrane proteins. 78 63

32P-labeled light chain messenger RNA was prepared from mouse MOPC 21 myeloma cells. The messenger RNA was hybridized to purified repetitive nuclear DNA and both the hybridized (repetitive 32P-RNA) and nonhybridized (nonrepetitive 32P-RNA) fractions were isolated. Only the nonhybridized RNA gave a T1 ribonuclease fingerprint showing oligonucleotides derived from the variable and constant regions of the light chain messenger RNA. In addition, this fingerprint showed oligonucleotides derived from the untranslated regions of the light chain messenger RNA. The nonrepetitive 32P-RNA was shown to rehybridize only with the unique fraction of total nuclear DNA. The rapidly hybridizing part of the unfractionated 32P-RNA preparation, therefore, is not a component of the light chain messenger RNA itself. Complementary DNA was prepared with reverse transcriptase using unlabeled light chain messenger RNA as template, and the transcripts were fractionated into various size classes. Complementary DNA molecules greater than 900 bases in length hybridized with both the initial messenger RNA and with the nonrepetitive 32P-RNA but failed to hybridize with excess purified repetitive 32P-RNA. The rapidly hybridizing component of the messenger RNA fraction, therefore, does not appear to be transcribed by reverse transcriptase. It is concluded that, under the experimental conditions used, the light chain messenger RNA hybridizes exclusively with unique DNA.
Cell 1975 Sep
PMID:Demonstration that a mouse immunoglobulin light chain messenger RNA hybridizes exclusively with unique DNA. 80 42

We have shown in our earlier paper (4) that a ribonuclease resistant filamentous network was associated with the fibrillar structures of the nucleolus of L 929 interphase nucleus. After desoxyribonuclease digestion and oxydised DAB opacification, the nucleolar fibrillar areas became heterogenous from an electron microscopical point of view. We have concluded that an important part of these fibrillar areas are composed of DNA and that the high electron dense fibrillar structures seen after desoxyribonuclease digestion, are the primary ribosomal gene product, just transcribed on the DNA matrix.
C R Acad Hebd Seances Acad Sci D 1975 Sep 29
PMID:[Ultrastructural demonstration of deoxyribonuclease-sensitive elements in fibrillar zones of the nucleoli of L 929 cell interphasic nuclei]. 81 97

Human spleen RNase was purified using an immunoabsorbant produced with anti-human liver RNase serum. The purification was more rapid than the procedure used to purify the liver RNase, yet the final specific activity was similar. Problems encountered previously using immunoabsorbants to purify enzymes were to a large degree avoided by injecting only microgram amounts of human liver RNase directly into the popliteal lymph nodes of rabbits, thereby producing a low avidity antibody. The low avidity antibody permitted elution from the immunoabsorbant with only dilute citrate buffer and without significant denaturation. An examination of crude spleen homogenates did not reveal any other RNase to be present except that which bound to the antibody. The enzyme was found to be antigenically unrelated to the human plasma RNase. A comparison of the physical properties of the human spleen enzyme with those of the human liver enzyme did not reveal any significant differences.
J Biol Chem 1976 Sep 25
PMID:Purification of human spleen ribonuclease by immunoabsorption. Similarity of the enzyme with human liver ribonuclease. 82 52

A comparison was made between rats fed diets containing either 5% casein or 25% casein, both being supplemented with DL-methionine, from the first day of pregnancy. Livers of dams killed on days 7, 14, and 21 and whole fetuses on days 12, 14, and 21 were weighed, analyzed for protein, RNA and DNA content and assayed for ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD). Free and total alkaline ribonuclease activity were also measured in the maternal livers. Malnutrition reduced the characteristic increase in content of DNA, RNA and protein in the maternal liver and fetus. In control rats total hepatic RNase activity increased and free RNase activity decreased during late pregnancy. In the deprived group, total activity decreased and free activity increased during late pregnancy. Liver and fetal ODC and SAMD activities were reduced by undernutrition. These studies show that malnutrition reduced both growth and the accretion of RNA in livers and fetuses of rat dams. These changes coincide with a reduced activity of polyamine synthesizing enzymes suggesting that there is a functional relationship between polyamines and RNA. High hepatic free RNase activity in malnourished dams may help to limit any build up in RNA content.
J Nutr 1977 Sep
PMID:Effects of malnutrition on some aspects of RNA metabolism in the maternal liver and fetal tissues at different stages of pregnancy in the rat. 89 66


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