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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction of adenylyl-3',5'-cytidine (ApC) with ribonuclease-A (RNAase-A) was studied by steady-state kinetics and ultraviolet difference spectroscopy. X-ray difference Fourier synthesis at 4 A resolution was also used to study the binding of ApC to RNAase-S. Unlike well-studied compounds like uridylyl-3',5'-adenosine, ApC binds in an unique way: (1) the cytidine moiety is bound to the B1 and R1 sites, (2) the adenosine moiety protrudes to the solution and is not fixed spatially and (3) the phosphate group is bound to the non-specific site (the "Po site") previously postulated (Sawada, F. and Irie, M. (1969) J. Biochem. (Tokyo) 66, 415--418) as the binding site for the 5'-phosphate of uridine 2',5'-diphosphate or uridine 3',5'-diphosphate. This conclusion is consistent with that derived for adenylyl-3',5' -4-thiouridine based on CD difference spectroscopy (White, M.D., Keren-Zur, M. and Lapidot, Y. (1977) Nucleic Acid Res. 4, 843--851). The "Po site" is most likely the epsilon-amino group of Lys 66.
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PMID:Studies on the binding of adenylyl-3', 5'-cytidine to ribonuclease. 67 53

32P-Labeled MS2 RNA was partially digested with ribonuclease T1 (guanyloribonuclease; ribonucleate 3'-guanylo-oligonucleotidohydrolase; EC 3.1.4.8) or with epilson-carboxymethyl-lysine-41 pancreatic ribonuclease A (ribonucleate 3'-pyrimidino-oligonucleotidohydrolase; EC 3.1.4.22). A series of overlapping fragments was obtained which allowed the reconstruction of a 361-nucleotide-long 3'-terminal sequence. A unique reading frame could be deduced, which indicated that the replicase gene ends with a U-A-G termination signal and is followed by a 174-nucleotide-long untranslated segment.
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PMID:3'-Terminal nucletide sequence (n equals 361) of bacteriophage MS2 RNA. 80 66

The antimicrobial action of polycation proteins from the nuclei--histons with a high content of lysine (f1) and arginine (f3)--on Pseudomonas bacteria was studied. The sensitivity of various species of the same genus, and various strains of the same species, to histons was differential. The differences do not depend on the ability of the cells to liberate into a surrounding medium substances inactivating histons, and on the rate of histon sorption on the cells. Interaction between the bacteria and histons interferes with the permeability of the membranes, so that components of a low molecular weight, including those with the maximum of absorption in UV at 260 nm, are liberated into the surrounding medium. The total RNA of the cells is depolymerized and the activity of RNase increases. No correlation was established between these phenomena and the sensitivity of the bacteria to histons. The duration of the lag period was also studied, as well as the growth rate in the exponential phase and the total yield of the cells; a positive correlation was detected between the duration of the lag period and the sensitivity of the bacteria to histons.
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PMID:[Differential sensitivity of bacteria to histones]. 82 Sep 44

A 63-residue RNase A analog containing residues 26 to 35 then alanine, 41 to 59 and 73 to 84 then glycine, 100 to 110 then glycine, and 117 to 124 was synthesized by the solid phase method. The deletions comprised ordered (an alpha helix, parts of the beta sheet) and less ordered structures including 27 of the 56 residues invariant in mammalian ribonucleases. The synthetic 63-residue analog was cleaved from the insoluble support with liquid HF, reduced-reoxidized, fractionated by gel filtration, and purified further on an affinity column specific for the active site fold of RNase A. It had an activity of 8 to 14 per cent in the transphosphorylation step using poly(C) and poly(U) as substrates. It also had low synthetic and hydrolytic activity (0.2 per cent) and showed RNase A-like specificity toward the substrates tested. This indicated that all residues essential for substrate binding and catalysis were present and that their relative positions in the three-dimensional structure were probably very similar to those in native RNase A. Therefore, structure-function studies with the 63-residue RNase A analog should allow conclusions about the mode of action of the natural enzyme. As a first step in this direction, lysine 41 which is believed to be important for catalysis was replaced in the 63-residue analog by tyrosine or glutamine. The resulting (Tyr-41)- and (Gln 41)-63-residue analogs were also bound by the affinity column and had the same substrate specificity as native RNase A. They differed from each other, from the (Lys 41)-63-residue analog, and the 124-residue natural enzyme only with respect to the relative rates of the catalyzed reactions. Thus, lysine 41 does not seem to be essential for the functioning of RNase A.
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PMID:Study of RNase A mechanism and folding by means of synthetic 63-residue analogs. 83 49

The membrane penicillinase of Bacillus licheniformis 749/C differs from the exopenicillinase in that it has an additional 24 amino acid residues and a phosphatidylserine at the NH2 terminus (Yamamoto, S., and Lampen, J.O. (1976) J. Biol. Chem. 251, 4095-4101). The conversion of the membrane penicillinase to the exo form is probably carried out by a specific penicillinase-releasing protease (PR-protease) whose properties are generally consistent with the properties of penicillinase secretion. The substrate specificity of the PR-protease was determined by identifying the NH2 and COOH termini of the peptides produced by hydrolysis of ribonuclease B and beef insulin. The enzyme hydrolyzed only peptide bonds involving the carboxyl groups of serine or thrombine. Similar bonds in synthetic di- or tripeptides of L-serine were not cleaved. The existence of seryl-lysine and threonyl-glucamic acid bonds in the protease-susceptible (phospholipopeptide) region of the membrane penicillinase and the presence of only lysine or glutamic acid at the NH2 terminus of the exoenzyme released in vivo are consistent with the specificity of PR-protease; hence, we propose that this enzyme has an essential role in the formation of exopenicillinase. The PR-protease is a potential tool for protein sequence determination because of its narrow and novel substrate specificity.
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PMID:Penicillinase-releasing protease of Bacillus licheniformis 749 Specificity for hydroxyamino acids. 83 38

A description is given of the synthesis by fragment condensation of the peptides Glu-Ser-Ser-Ala-Asp-Lys-Phe-Lys-Arg-Gln-His-Met-Asp and Gly-Glu-Ser-Arg-Glu-Ser-Ser-Ala-Asp-Lys-Phe-Lys-Arg-Gln-His-Met-Asp respectively corresponding to the 5-17 and 1-17 amino acid sequences of rat pancreatic ribonuclease.
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PMID:Studies on polypeptides. XXIV. Synthesis of the 5-17 and 1-17 peptide sequences of rat pancreatic ribonuclease. 89 88

The involvement of lysine residues in the active site of pancreatic ribonuclease has been investigated by assessing (a) the degree of substrate and substrate analogue protection of individual lysine residues against acetylation, and (b) the individual contribution of remaining unacetylated lysine residues to the total catalytic activity of the enzyme. Different substrate analogues (RNA digest, CMP, ATP, and pyrophosphate) were found to give different degrees of protection against acetylation with acetic anhydride. Instead of the expected specific protection of active site lysine residues such as lysine-7 and lysine-41, however, a general decrease in reactivity of all the lysines was observed when the substrate analogues were present during the acetylation. The fraction of enzymatic activity remaining in the protected samples was consistently greater than the fraction of any one lysine remaining unacetylated, and was found to correspond fairly well with the sum of the fractions of unacetylated lysine-7, lysine-41, and a third residue, tentatively assigned as lysine-66. This is consistent with other observations of ribonuclease which suggest that while no lysine residue interacts with substrate and substrate analogues in the formation of the Michaelis-Menten complex, a lysine amino group is required for catalysis. It is proposed that this lysine amino group can be supplied by any one of two or three lysine residues (7, 41, and 66) located close to the substrate binding site.
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PMID:The role of lysine in the action of bovine pancreatic ribonuclease A. 94 54

Pancreatic ribonucleases from several species (whitetail deer, roe deer, guinea pig, and arabian camel) exhibit more than one amino acid at particular positions in their amino acid sequences. Since these enzymes were isolated from pooled pancreas, the origin of this heterogeneity is not clear. The pancreatic ribonucleases from 11 individual arabian camels (Camelus dromedarius) have been investigated with respect to the lysine-glutamine heterogeneity at position 103 (Welling et al., 1975). Six ribonucleases showed only one basic band and five showed two bands after polyacrylamide gel electrophoresis, suggesting a gene frequency of about 0.75 for the Lys gene and about 0.25 for the Gln gene. The amino acid sequence of bactrian camel (Camelus bactrianus) ribonuclease isolated from individual pancreatic tissue was determined and compared with that of arabian camel ribonuclease. The only difference was observed at position 103. In the ribonucleases from two unrelated bactrian camels, only glutamine was observed at that position.
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PMID:Allelic polymorphism in arabian camel ribonuclease and the amino acid sequence of bactrian camel ribonuclease. 96 46

Pancreatic tissue from topi (Damaliscus korrigum) contains three ribonuclease components in a ratio of 8:22:70. Two components are glycosidated, whereas the third one does not contain carbohydrate. The amino acid sequence of topi ribonuclease A was deduced from a tryptic digest of the performic acid-oxidized protein. Peptides were positioned by homology with other bovid ribonucleases. Only peptides that differed in amino acid composition from the corresponding peptides of bovine ribonuclease were sequenced. The evidence obtained for the sequence of residues 67-73 is incomplete. Among the bovid ribonucleases (cow, bison, eland, sheep, goat and gnu), topi ribonuclease shows the closest resemblance with sheep and goat ribonucleases; except that the glutamic acid residue at position 103 in the ribonucleases from sheep and goat is substituted by a lysine residue in topi. Topi ribonucleases A and B differ only in the presence of carbohydrate attached to asparagine 34.
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PMID:The amino acid sequence of topi pancreatic ribonuclease. 99 Feb 82

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.
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PMID:New method for determination of free amino groups in intact pure proteins: relationship to available lysine. 99 78


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