Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of cis-Pt(NH3)2B1B2 to the bases B1 and B2, i.e., guanine (G), cytosine (C), adenine (A), and thymine (T), of DNA is studied theoretically. The components of the binding are analyzed and a model structure is proposed for the intrastrand binding to the dB1pdB2 sequence of a kinked double helical DNA. Quantum mechanical calculations of the ligand binding energy indicates that cis-Pt(NH3)2(+2) (cis-PDA) binds to N7(G), N3(C), O2(C), O6(G), N3(A), N7(A), O4(T) and O2(T) in order of decreasing binding energy. Conformational analysis provides structures of kinked DNA in which adjacent bases chelate to cis-PDA. Only bending toward the major groove allows the construction of acceptable square planar complexes. Examples are presented for kinks of -70 degrees and -40 degrees at the receptor site to orient the base pairs for ligand binding to B1 and B2 to form a nearly square planar complex. The energies for complex formation of cis-PDA to the various intra-strand base sites in double stranded DNA are estimated. At least 32 kcal/mole separates the energetically favorable dGpdG.cis-PDA chelate from the dCpdG.cis-PDA chelate. All other possible chelate structures are much higher in energy which correlates with their lack of observation in competition with the preferred dGpdG chelate. The second most favorable ligand energy occurs with N3(C). A novel binding site involving dC(N3)pdG(N7) is examined. Denaturation can result in an anti----syn rotation of C about its glycosidic bond to place N3(C) in the major groove for intrastrand binding in duplex DNA. This novel intrastrand dCpdG complex and the most favored dGpdG structure are illustrated with stereographic projections.
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PMID:A theoretical model for the binding of cis-Pt(NH3)2(+2) to DNA. 391 46

Modification of human placenta DNA polymerase alpha by (pT)2pC[Pt2 + (NH3)2OH].(pT)7 was investigated. The linear time dependence of the enzyme activity logarithm suggested a pseudo-first order for modification. Kd value of enzyme-affinity reagent complex (0.5 microM) was estimated. The enzyme inactivation by the affinity reagent and protection from inactivation in the presence of oligonucleotides of varying length were used for determining Kd values of the enzyme-ligand complexes. Oligonucleotide d(pT)2pC(pT)7 (Kd 0.15 microM), d(Tp)9T (Kd 0.15 microM) and [d(Tp)9]ddT (Kd 0.15 microM) protected the enzyme from inactivation with equal efficiency. The protective action of oligothymidylates d(Tp)nT (where n changes from 3 to 14) strongly depended on the chain length, the Kd values diminishing from 5.3 to 0.0091 microM in the geometrical progression. The addition of one link to the oligothymidylate chain resulted in 1.71-fold increase in the oligonucleotide affinity for the enzyme specific site. Such a change corresponds to Gibbs energy change of about 0.32 kcal/mole. It is supposed that the monomer units of pentadecathymidylate (at least beginning with the third one) in d(Tp)14T-enzyme complex form neither hydrogen bonds nor electrostatic linkages with the enzyme. Kd values of oligonucleotides as templates are shown to reflect quite well the true affinity of template for the enzyme. This affinity increases in the presence of a primer. However, the ratio of the affinity for different oligonucleotides does not change in the presence or absence of a complementary primer.
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PMID:[DNA-polymerase alpha from human placenta. Effectiveness of interaction between oligothymidylates of different lengths and the template-binding site]. 396 8

The N-terminal formic acid fragment (FA1) of the N-[3H]ethylmaleimide-labeled and carboxymethylated bovine mitochondrial phosphate transport protein (PTPN*CM) has been purified and completely sequenced: NH2-Ala-Val-Glu-Glu-Gln-Tyr-Ser-Cys-Asp-Tyr10-Gly-Ser-Gly-Arg-Phe- Phe-Ile-Leu-Cys- Gly20-Leu-Gly-Gly-Ile-Ile-Ser-Cys-Gly-Thr-Thr30-His-Thr -Ala-Leu-Val-Pro-Leu-Asp- -Leu-Val40-Lys-Cys(N-[3H]ethylmaleimide)-Arg-Met-Gln-Val-Asp- COOH. By thermolysin digestion of FA1 and high-performance liquid chromatography isolation of the radioactive subfragment Leu39-Arg43, the sole N-ethylmaleimide-binding residue has been identified as Cys42. FA1 contains a high mole percentage of cysteine (8.5%) and shows silver staining anomaly. Its sequence reveals significant homology in the triplicated gene regions (Pro27,132,229) of the mitochondrial ADP/ATP carrier from beef heart and Neurospora crassa. The hydropathic profile suggests that FA1 contains a transmembrane segment (Phe15-Val40) with only one basic (His31) and one acidic (Asp38) residue. The presence of the phosphate transport protein gene among nuclear genes is suggested from a lack of significant homology between the reverse-translated FA1 (mitochondrial codons) and the bovine mitochondrial genome. The inhibitory action of N-ethylmaleimide on the phosphate transport mechanism is discussed.
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PMID:Sequence of the N-terminal formic acid fragment and location of the N-ethylmaleimide-binding site of the phosphate transport protein from beef heart mitochondria. 406 97

The growth constant and Y (sucrose) (grams of cells per mole of sucrose) for NH(3)-grown cultures of Clostridium pasteurianum were 1.7 times those of N(2)-grown cultures, whereas the rate of sucrose utilized per gram of cells per hour was similar for both conditions. The Y (sucrose) of chemostat cultures grown on limiting NH(3) under argon at generation times equal to those of N(2)-fixing cultures was less than that of cultures grown on excess NH(3), but cells of NH(3)-limited cultures contained the N(2)-fixing system in high concentration. The concentration of the N(2)-fixing system in whole cells, when measured with adenosine triphosphate (ATP) nonlimiting, was more than twofold greater than the amount needed for the N(2) actually fixed. Thus, energy production from sucrose, and not the concentration of the N(2)-fixing system nor the maximal rate at which N(2) could be fixed, was the limiting factor for growth of N(2)-fixing cells. Either NH(3) or some product of NH(3) metabolism partially regulated the rate of sucrose metabolism since, when cultures fixing N(2), growing on NH(3), or growing on limiting NH(3) in the absence of N(2) were deprived of their nitrogen source, the rate of sucrose catabplism decreased. Calculations showed that the rate of ATP production was the growth rate-limiting factor in cells grown on N(2), and that the increased sucrose requirement of N(2)-fixing cultures in part reflected the energy demand of N(2) fixation. Calculations indicated that whole cells require about 20 moles of ATP for the fixation of 1 mole of N(2) to 2 moles of NH(3).
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PMID:Sucrose catabolism in Clostridium pasteurianum and its relation to N2 fixation. 567 50

The accessibility of F1-ATPase from Micrococcus lysodeikticus in solution and in the membrane for the specific water-soluble NH2-group reagent, 2,4,6-trinitrobenzosulfonate (TNBS), was studied. Incubation of the soluble factor F1 with 50 mM TNBS pH 8.3 results in incorporation of 58.6 +/- 4.4 trinitrophenyl residues per mole of enzyme. At the same time F1-ATPase isolated from TNBS-pretreated membranes contains 27.2 +/- 2.0 TNP-residues per mole of enzyme. It is assumed that the different accessibility of F1-ATPase for TNBS in solution and in the membrane is due to incorporation of F1-ATPase into the membrane. Study of membrane F1-ATPase interaction with the radioactive lipid-soluble photoreactive label, 12-0-(azidoformyl) stearic acid methyl ester demonstrated that F1-ATPase does not immediately interact with the lipid phase of the membrane. It is suggested that membrane F1-ATPase may be enveloped by hydrophobic proteins.
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PMID:[Submergence of Micrococcus lysodeikticus F1-ATPase into the hydrophobic phase of the membrane, using 2,4,6-trinitrobenzosulfonate and 12-0-(azidoformyl) stearic acid methyl ester]. 621 15

Background generated during the cleavage step of the Edman degradation is a major obstacle to extended automated amino acid sequencing. It was demonstrated recently by A. S. Bhown, J. C. Bennett, P. H. Morgan, and J. E. Mole (1981, Anal. Biochem. 112, 158-162) that introduction of fluorescamine into the spinning cup reduced background by blocking primary amino groups at cycles where a proline residue is at the exposed amino terminus. A convenient blocking reaction program using o-phthalaldehyde which can be intercalated into the sequencing format of an automated Beckman liquid-phase sequencer is presented. The advantages of o-phthalaldehyde in blocking of primary amines when proline is amino terminal arise from its stability in aqueous solution and the ease of programmed metering of delivery to the sequencer spinning cup. The blocking reaction proved successful not only in extending sequence analyses but also in the elimination of unwanted sequences in selected peptide mixtures without the necessity of purification of the target peptide.
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PMID:Use of o-phthalaldehyde to reduce background during automated Edman degradation. 642 62

Four of the principle apolipoproteins of murine serum have been isolated and characterized. On the basis of their physicochemical properties, they are homologous with the human and rat apoA-I, A-II, B, and C-III. The group of apolipoproteins of middle to low molecular weight, i.e., A-I, A-II and C-III, were separated from the protein moiety of high density lipoproteins (HDL) by gel filtration chromatography, followed by electrophoresis in alkaline-urea polyacrylamide gel with electrophoretic elution. Murine apoA-I, the major protein of HDL (60-80%) displayed an Mr of approximately 27,000, and was polymorphic (four prominent isoproteins with isoelectric points in the range of pH 5.5-5.7). The amino acid profiles of mouse, rat, and human apoA-I generally resembled each other, the former being distinguished by a content of one isoleucine residue per mole. Amino terminal sequence analysis revealed marked homology between the mouse, rat, dog, and human proteins; mouse and rat apoA-I differed at residues 9 and 18 with potential dissimilarities at residues 5 and 15, while the murine and canine sequences were distinct at residues 6, 9, 13, 15, and 30. Apolipoprotein A-II was a monomer, exhibiting an Mr approximately 11,000 in SDS gels; in addition, it was polymorphic (three apparent isoproteins with pI in the pH range 5.05-5.2), and resembled its human and rat counterparts in amino acid composition. ApoC-III, an acidic peptide of pI 4.74 and of Mr approximately 9,600, possessed an amino acid composition very like that of the homologous human and rat proteins. The homology of mouse apoC-III with the human protein was confirmed by NH2-terminal sequence analysis, which revealed identical amino acids in six positions (1, 2, 4, 8, 9, and 13). As shown earlier (Camus et al. 1983. J. Lipid Res. 24: 1210-1228), two forms of immunologically reacting apoB predominated in mouse VLDL and LDL. After isolation of these lipoproteins in the presence of 1 mM PMSF, the apparent sizes of the high and low Mr forms, apoBH and apoBL, were in the ranges approximately 400,000-530,000 and approximately 250,000-280,000, respectively, according to the SDS gel system. We observed that inclusion of 1 mM PMSF was essential to retard degradation of the high Mr form apoBH. The murine B proteins were isolated from apoVLDL and apoLDL by gel filtration chromatography on Sephadex G150 in anionic detergent, and displayed apparent Mr values of 460,000 (apoBH) and 250,000 (apoBL) in 3% SDS gels.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The lipid transport system in the mouse, Mus musculus: isolation and characterization of apolipoproteins B, A-I, A-II, and C-III. 643 19

Amine N-oxides have been observed to be reduced by titanium(III) chloride. To study this reaction, 24 model amine N-oxides were reacted with titanium(III) chloride. The products of these reactions were shown by melting (boiling) points, mixed melting points, derivatives, refractive indices, infrared, and NMR comparisons with authentic compounds to be the corresponding amines. The reductions were found to require 2 moles of titanium(III) per mole of amine N-oxide.
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PMID:The reduction of aliphatic and aromatic N-oxides to the corresponding amines with titanium(III) chloride. 673 44

The purpose of this paper is to compare the role of UV light and of electric discharges, the two most important sources of energy on the primitive earth, in the synthesis of organic compounds out of a reducing model of that atmosphere. Since Miller's experiments in 1953, most of the experimental simulations have been performed with electric discharges, and it has been assumed that UV radiations would give similar results. In order to check this assumption we have performed both experimental simulations in our laboratory. Experimental results indicate that this assumption was wrong in a large extent. Our four main conclusions are: 1. Unlike electric discharges, UV light is not an efficient source for producing unsaturated carbon chains. 2. UV light is efficient for producing nitriles in CH4--NH3 mixtures when the mole fraction of NH3 is very low while electric discharges need a higher mole fraction of NH3. 3. UV light is not able to produce nitriles from CH4--N2 mixtures while electric discharges produce important quantities of diversified nitriles from these mixtures. 4. UV light is not very efficient for producing aldehydes from CH4--H2O model atmosphere, electric discharges seem to be able to produce them more efficiently.
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PMID:Organic synthesis from reducing models of the atmosphere of the primitive earth with UV light and electric discharges. 709 76

Photolysis of NH3 at 185 nm in the presence of a two-fold excess of CH4 results in the loss of about 0.25 mole of CH4 per mole of NH3 decomposed (delta CH4/delta NH3). The loss arises from the abstraction of hydrogen atoms from CH4 by photolytically generated hot hydrogen atoms, the presence of which is established by the constancy of delta CH4/delta NH3 between 298 and 156 K and by the quenching of the abstraction reaction when either H2 or SF6 is added. From the latter result, it can be concluded that NH3 photolysis in the H2-abundant atmosphere of Jupiter is not responsible for the presence of the carbon compounds observed there such as ethane, acetylene, and hydrogen cyanide, but may have had a role in the early atmosphere of Titan. Photolysis of PH3 with a 206 nm light source gives P2H4, which in turn is converted to a red-brown solid (P4?). The course of the photolysis is not changed appreciably when the temperatures is lowered to 157 K except that the concentration of P2H4 increases. The presence of H2 has no effect on the P2H4 yield. Photolysis of 9:1 NH3:PH3 gives a rate of decomposition of PH3 that is comparable with that observed by the direct photolysis of PH3. Comparable amounts of P2H4 and the red-brown solid are also observed. The mechanisms of these photochemical reactions together with their implications to the atmospheric chemistry of Jupiter are discussed. The structures of the compounds responsible for the wide array of colors e.g., brown, red and white, observed in the atmosphere of Jupiter have been the subject of extensive speculation. One theory suggests that these colors are due to organic materials formed by the action of either solar ultraviolet light or electric discharges on mixtures of CH4, NH3 and NH4HS in the Jovian atmosphere (Ponnamperuma, 1976; Khare et al., 1978). An alternative hypothesis is that the colors are due to inorganic compounds resulting from the photolysis of NH4HS and PH3 (Lewis and Prinn, 1970; Prinn and Lewis, 1975). In this paper we will summarize our experiments which were designed to test some of these hypotheses.
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PMID:Photochemistry of NH3, CH4 and PH3. Possible applications to the Jovian planets. 716


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