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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The usefulness of plasma ribonuclease assays was studied in (i) patients with possible protein deficiency, (ii) patients with myelomatosis, (iii) patients with carcinoma of the breast. In each group, the major factor associated with elevation of plasma ribonuclease was impairment of renal function. The assay was therefore of little value in the assessment of patients with myelomatosis or carcinoma of the breast. However, in the patients with possible protein deficiency and normal renal function, an elevation of plasma ribonuclease is, in general, associated with a decrease in serum albumin, transferrin and cholinesterase. Plasma ribonuclease may therefore be a useful parameter in the assessment of protein nutritional status.
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PMID:An assessment of the clinical usefulness of plasma ribonuclease assays. 97 78

A process for conformational modification of protein, which we have previously reported, was investigated as a means of generating fluorohydrolase activity in bovine ribonuclease (RNase). The resulting modified RNase had catalytic activity that depended upon the chosen modifier. Bovine pancreatic ribonuclease, modified by addition of hexamethylphosphoramide (HMPA) at pH 3, was derivatized with diimidates of chain lengths from C1 to C8. The derivative with the highest activity was obtained when RNase was crosslinked with dimethyl pimelimidate (C5). This derivative, which was active over a pH range of 6.5 to 8.0 with an optimum pH of 7.4, hydrolyzed phenylmethylsulfonylfluoride (PMSF) and the potent acetylcholinesterase inhibitor, diisopropyl phosphorofluoridate (DFP). The mean fluorohydrolase activity for four preparations using dimethyl pimelimidate was 0.8 +/- 0.2 U mg-1. Gel filtration on G-75 Sephadex and SDS-polyacrylamide gel electrophoresis showed components having a molecular weight of 13,000 and 27,000, with activity restricted to the 27,000 molecular weight fraction. After gel filtration, the specific activity was 9.1 +/- 2.4 U mg-1, resulting in a molecular activity of 125 min-1. The mechanism of this unique transformation of RNase into a fluorohydrolase is not known, nor has the location of the active site been determined.
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PMID:Semisynthetic fluorohydrolases prepared by chemical modification of ribonuclease. 136 89

The venom from Crotalus molossus nigrescens contains many activities including: hyde powder azure proteinase; N-benzoyl-arginine-ethyl-ester hydrolase; phospholipase; phosphodiesterase; desoxyribonuclease; fibrinogen coagulase; collagenase, fibrinolytic activity, and hemorrhagic factors. The venom, assayed with amounts of venom up to 50 micrograms protein per assay, does not contain acetylcholinesterase, phosphatase, amylase, ribonuclease, tyrosyl-ester hydrolase or hyaluronidase activities. The venom is lethal to mice with an i.p. LD50 of 2.35 mg/kg mouse. Fractionation of soluble venom by Sephadex G-75 separates at least five families of components. Fractions I-III contains all the enzymes, and fraction V have six small peptides. Further separation of fractions II-III on diethyl-amino-ethyl-cellulose columns at pH 8.0 and 8.3 gave pure proteinase E with a mol. wt of 21,390 and the following N-terminal amino acid sequence; Phe-Ala-Lys-Arg-Tyr-Val-Glx-Leu-Val-Ile-Val-Ala. A thrombin-like enzyme with a mol. wt of 75,000 was also purified from this venom by means of affinity and ion exchange chromatographies.
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PMID:Characterization of the venom from Crotalus molossus nigrescens Gloyd (black tail rattlesnake): isolation of two proteases. 218 98

Acetylcholinesterase exists predominantly as a secreted enzyme which remains cell-associated at specific extracellular locations. Its extensive structural diversity appears responsible for the unique cellular disposition of the enzyme. To examine the molecular basis of the structural divergence of acetylcholinesterase species, we hybridized total RNA from Torpedo californica electric organ with restriction fragments from a cDNA encoding the catalytic subunits of asymmetric species of acetylcholinesterase. Multiple RNA species up to 14 kilobases in length can be detected on Northern blots using a full-length cDNA for hybridization. Each of these RNA species also hybridizes with smaller restriction fragments within the open reading frame and 3'-untranslated region of the cDNA. This indicates that the entire open reading frame plus the 3'-untranslated region is contained in the large RNA species. RNase protection experiments revealed at least three points of divergence for the message species. One occurs within the COOH-terminal portion of the open reading frame at a position just 5' to the TGA stop codon. This divergence accounts for the two classes of acetylcholinesterase found in abundance in Torpedo. The site of splicing has been further defined by isolating a genomic clone containing the exon serving as the potential splice donor. We find a divergence between the cDNA and genomic DNA at the position estimated by the protection experiments. A less abundant divergence in mRNA can also be detected in the 3'-untranslated region. Another divergence occurs as a deleted sequence within the 5'-noncoding region and may be important for controlling translation efficiency. Since it is hypothesized that a single gene encodes acetylcholinesterase, the divergences in the very 3' region of the open reading frame and the 5'-noncoding region correspond to presumed splice junction boundaries where alternative RNA splicing occurs.
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PMID:Multiple messenger RNA species give rise to the structural diversity in acetylcholinesterase. 319 6

1. The action of beryllium on the following enzymes has been examined: alkaline phosphatase (Escherichia coli and kidney), acid phosphatase, phosphoprotein phosphatase, apyrase (potato), adenosine triphosphatase (liver nuclei, liver mitochondria, brain microsomes), glucose 6-phosphatase, polysaccharide phosphorylases a and b, phosphoglucomutase, hexokinase, phosphoglyceromutase, ribonuclease, A-esterase (rabbit serum), cholinesterase (horse serum), chymotrypsin. Alkaline phosphatase and phosphoglucomutase are inhibited by 1mum-beryllium sulphate whereas the other enzymes are largely unaffected by 1mm-beryllium sulphate. 2. Possible mechanisms for the inhibition of phosphoglucomutase and alkaline phosphatase are discussed.
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PMID:The inhibition of enzymes by beryllium. 428 87

Serum levels of various hydrolytic enzymes in prostatic cancer patients with or without bone metastasis were compared with those in patients with prostatic hypertrophy and in the control subjects. The enzymes tested included 11 aminopeptidases, 2 endopeptidases, dipeptidyl carboxypeptidase, esterase, acetyl cholinesterase, and RNase. Although most of the enzymatic levels tended to be decreased in the cancer patients without bone metastasis, they tended to be increased in those with metastasis as well as in the patients with prostatic hypertrophy. Thus, bone metastasis is an important factor affecting the serum levels of hydrolytic enzymes in cancer patients. Of the enzymes tested, RNase was unique in that its serum levels were significantly increased regardless of the existence of bone metastasis. This enzyme may become a marker of malignancy.
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PMID:Different tendencies of changes in hydrolytic enzyme activities in sera from prostatic cancer patients with or without bone metastasis. 608 28

Double-labeling immunofluorescent histochemistry demonstrates that calretinin, a calcium-binding protein, coexists with calcitonin gene-related peptide, vasoactive intestinal peptide, and substance P in the fibers innervating the lamina propria of the rat intestinal villi. An acetylcholinesterase histochemical stain revealed that the majority of calretinin-containing cells in the myenteric ganglia were cholinergic and that about one half of the submucosal calretinin-containing cells colocalized with acetylcholinesterase. In situ hybridization studies confirmed the presence of calretinin mRNA in the dorsal root ganglia, and a ribonuclease protection assay verified the presence of calretinin message in the intestine. The coexistence of calretinin in calcitonin-gene-related-peptide-containing cells that also contained substance P and vasoactive intestinal polypeptide in the dorsal root ganglia suggest that these ganglia are the source of the quadruple colocalization within the sensory fibers of the villi. Although the function of calretinin in these nerves is unknown, it is hypothesized that the coexistence of three potent vasodilatory peptides influences the uptake of metabolized food products within the vasculature of the villi.
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PMID:Quadruple colocalization of calretinin, calcitonin gene-related peptide, vasoactive intestinal peptide, and substance P in fibers within the villi of the rat intestine. 754 20

The 5'-untranslated region of the mouse acetylcholinesterase gene has been characterized structurally by RNase protection, primer extension, and sequencing. Evidence has been obtained for the use of two alternative promoters in brain. Tissue-specific splicing to alternative acceptor sites in the 5'-untranslated exons occurs in brain, muscle, and erythropoietic cells. cis elements 5' of the cap site that is predominantly used in these tissues and cells have been analyzed by deletion analysis of promoter-reporter gene constructs and by site-specific mutagenesis. The cap site is found 107 base pairs (bp) 5' of the translation start site. This region is devoid of CAAT or TATA sequences; further in the 5' direction 50 and 70 bp are tandem Egr-1 sites. The putative promoter has been coupled to the open reading frame of a luciferase reporter gene. Deletion analysis shows that this region largely accounts for tissue-specific transcription seen upon transfection of neuronal and muscle cells. Mutagenesis of the Egr-1 sites results in a marked loss of reporter gene activity, further substantiating the importance of this region in the control of transcription. cis elements in the promoter differ from those found for the genes encoding the various subunits of the nicotinic acetylcholine receptor, and distinct differences in control of transcription are evident when the respective reporter genes are transfected into C2 muscle cells.
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PMID:Promoter elements and transcriptional control of the mouse acetylcholinesterase gene. 842 32

L-type Ca2+ channels play critical roles in achieving stabilization of acetylcholinesterase (AChe) mRNA during myogenesis in C2-C12 skeletal muscle cells. To ascertain the importance of this signaling pathway in AChE expression during skeletal muscle development in the animal, we examined AChE mRNA levels in skeletal muscle and heart from control (+/+) and muscular dysgenic (mdg/mdg) mice that lack the skeletal, but not the cardiac, muscle L-type Ca2+ channels. RNase protection analysis showed 40-60% reductions in content of AChE mRNA in leg muscle, but not heart, from newborn and day 18 embryonic dysgenic mice. AChE activity was also reduced uniquely in skeletal muscle. In contrast to AChE transcripts, mRNA levels of the alpha-subunit of the nicotinic acetylcholine receptors (nAChRs) were increased in dysgenic skeletal muscle. Similar alterations in activity and mRNA levels of AChE were also observed form skeletal muscle cell lines derived from mdg mice. Because run-on transcription revealed no corresponding decrease in transcription rate, the decrease in mRNA content is likely a consequence of the inability of the dysgenic muscle cells to stabilize AChE mRNA during differentiation. These findings indicate that L-type Ca2+ channels play an important role in regulation of AChE expression during skeletal muscle development in vivo. The differential influence of muscle dysgenesis on mRNA levels of AChE and nAChRs provides additional evidence for distinct mechanisms of regulation of these two proteins.
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PMID:Acetylcholinesterase and nicotinic acetylcholine receptor expression diverge in muscular dysgenic mice lacking the L-type calcium channel. 866 81

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.
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PMID:Ophidian envenomation strategies and the role of purines. 1173 31


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