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K Dose

Publications and source records attributed to K Dose.

At least 55 records · Page 3Linked to original sources
PubMed1980

Isolation and characterization of the novel polyadenylate- and polyuridylate-degrading acid endoribonuclease V from calf thymus.

A novel endoribonuclease was detected and purified to homogeneity from calf thymus. The homogeneity was checked by analysis in polyacrylamide gels (both in the presence and in the absence of sodium dodecyl sulfate) as well as by isoelectric focusing. This nuclease activity, which is called Endoribonuclease V, cleaves poly(A) and poly(U); other single- or double-stranded synthetic polyribo- as well as polydeoxyribonucleotides are not degraded. Endoribonuclease V cleaves poly(A) to create first oligoribonucleotides and ultimately 3'-AMP; no P-2':3'-Ado degradation products were detected. The enzyme has a pH optimum of 5.8, an isoelectric point of pH 6.3, a molecular weight of 52,300, and requires neither monovalent nor divalent cations. The enzyme activity is not inhibited by N-ethylmaleimide.

Animals↗
PubMed1980

Purification and characterization of a poly(A)-specific exoribonuclease from calf thymus.

An exoribonuclease from calf thymus which specifically cleaves poly(A) in the single- or in the double-stranded form has been isolated and purified to homogeneity. The enzyme has a molecular weight of about 80,000 as estimated by gel filtration, and consists of two subunits with molecular weights of 58,000 and 31,000 as analyzed by sodium dodecyl sulfate-gel electrophoresis. For optimal activity, the poly(A)-specific exoribonuclease requires divalent cations, alkaline pH, and 39 degrees C. The enzyme is inhibited at 0.2 ionic strength and is sensitive to reagents for thiol groups. The only product formed by the action of the enzyme is 5'-AMP. It is suggested that this enzyme plays a role in the degradation of the poly(A) sequence of mRNA in the nucleus.

Animals↗
PubMed1980

Energy-linked reactions catalyzed by the purified ATPase complex (F0F1) from Rhodospirillum rubrum chromatophores.

1. The isolation of F0F1-ATPase complex from Rhodospirillum rubrum chromatophores by the use of taurodeoxycholate is described. 2. The enzyme preparation contains about 12 polypeptides; five are subunits of the F1 moiety. 3. The ATPase activity of the purified enzyme is dependent on the addition of phospholipids. 4. Km-vales for Mg2+-ATP and Ca2+-ATP are similar to the values obtained for the membrane-bound enzyme. 5. The F0F1-ATPase complex is more than 70% inhibited by oligomycin and N,N'-dicyclohexylcarbodiimide. 6. The F0F1-ATPase complex was integrated into liposomes. The reconstituted proteoliposomes catalyzed energy transduction as shown by ATP-dependent quenching of acridine dye fluorescence and ATP-32Pi exchange.

Adenosine Triphosphatases↗
PubMed1979

Immunological and reconstitution studies on the adenosine triphosphatase complex from Rhodospirillum rubrum.

Studies on restoration of membrane-bound adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3) from Rhodospirillum rubrum show that the delta-subunit is capable of binding to the F1 factor or to the F0 moiety of the F0-F1 ATPase complex. This subunit is thus likely involved in linking the F0 and F1 factor. During solubilization of the oligomycin-sensitive F0-F1 ATPase complex with Triton X-100 the detergent becomes specifically associated with the lipophilic F0 part of the enzyme complex. Crossed immunoelectrophoresis, agglutination tests, and kinetic studies with anti-F1 ATPase antibodies reveal a reaction of immunological identity of membrane-bound ATPase, F0-F1 ATPase, and F1 ATPase.

Adenosine Triphosphatases↗
PubMed1979

A special photoproduct of UV-irradiated DNA in vacuo.

DNA isolated from E. coli B/r cells was UV-irradiated at 254 nm under high vacuum of 10(-7) torr. Compared with DNA in solution, the formation of cis-syn thymine dimers (TT) was decreased, and the formation of cytosine thymine dimers (CT) and a photoproduct of RF value 0.41 was increased. The latter photoproduct was identified as tran-syn TT which is preferentially produced in heat-denaturated DNA.

DNA Damage↗
PubMed1979

Properties of the F0F1 ATPase complex from Rhodospirillum rubrum chromatophores, solubilized by Triton X-100.

1. A cold-stable oligomycin-sensitive F0F1 ATPase complex from chromatophores of Rhodospirillum rubrum FR 1 was solubilized by Triton X-100 and purified by gel filtration. 2. The F0F1 complex is resolved by sodium dodecyl sulfate electrophoresis into 14 polypeptides with approximate molecular weights in the range of 58000--6800; five of these polypeptides are derived from the F1 moiety of the complex which carries the catalytic centers of the enzyme. 3. The purified F0F1 complex is homogeneous according to analytical ultracentrifugation and isoelectric focusing. 4. The molecular weight as determined by gel filtration is about 480 000 +/- 30 000. S020,w is 1.45 +/- 0.1 S and the pI is 5.4. 5. The amino acid composition of the F0F1 complex is compared with the data obtained for the F1 moiety of the enzyme. 6. Quantitative data on the sensitivity to N,N'-dicyclohexyl-carbodiimide as well as kinetic parameters, regarding substrate specificity and dependence of ATPase activity on divalent cations, are reported.

Adenosine Triphosphatases↗
PubMed1979

Malignancy-associated DNA-binding protein C3DP from human serum. Further characterization and purification of C3DP retaining its DNA-binding affinity.

C3DP, a malignancy-associated DNA-binding protein from human serum[1], was purified to homogeneity without loss of its DNA-binding affinity. For this purpose normal human serum was submitted to affinity chromatography on Con A-Sepharose and DNA-cellulose and to preparative polyacrylamide gel electrophoresis. The purified C3DP was identified by immunodiffusion and sodium dodecylsulfate polyacrylamide gel electrophoresis and it was shown to bind to DNA by DNA-cellulose chromatography. The isoelectric point of C3DP was determined to 4.9 by isoelectric focusing.

Chromatography, Affinity↗
PubMed1978

8-Azido-adenosine 5'-triphosphate as a photoaffinity label for bacterial F1 ATPase.

1. 8-Azido-adenosine 5'-triphosphate (n83ATP) is a suitable photoaffinity label for F1 ATPase from Micrococcus luteus. The nucleotide is a substrate in the presence of bivalent cations and inhibits the enzyme irreversibly upon irradiation with ultraviolet light above 300 nm. 2. More than 80% of the label is covalently bound to the beta subunits in the presence of bivalent cations. Labeling and inactivation is decreased by protection with ADP, ATP or adenyl-5'-yl imidodiphosphate. To a much smaller degree the alpha subunits also become labeled. 3. n83AMP does not specifically bind to the beta subunits upon irradiation. Like n83ATP and n83ADP, it also labels the alpha subunits to a small extent. 4. The F1 ATPase is inactivated after a single beta subunit per F1 complex has become labeled. A cooperativity of the beta subunits carrying nucleotide binding sites is suggested.

Adenine Nucleotides↗
PubMed1978

Kinetic studies on bacterial plasma membrane ATPase (F1). Nucleotide-induced long term inactivation of ATP hydrolyzing activity is linked to the formation of multiple "tight" enzyme nucleotide complexes.

ADP and the ATP analogs Nb-S6ITP (6-[(3-carboxy-4-nitrophenyl)thio]-9-beta-D-ribofuranosylpurine 5'-triphosphate) and AMP-P(NH)P (adenyl-5'-yl imidodiphosphate) interact with soluble plasma membrane ATPase (F1) from Micrococcus species in two ways: (i) at short incubation times, these inhibitors exhibit the kinetics of competitive inhibition, (ii) at long incubation times, these inhibitors induce an inactivation of the ATPase which can be reversed only in the case of AMP-P(NH)P. Kinetic treatment of the long term inactivation by ADP or Nb-S6ITP reveals a pseudo-first order process via the formation of an enzyme-inhibitor complex for which a Km analogous constant is obtained that is identical with the corresponding Ki value of the competitive inhibition. The long term inactivation by ADP and Nb-S6ITP involves the successive "tight" binding of 6 +/- 1 nucleotides/F1 molecule. One additional ADP molecule/F1 complex which is also "tightly" bound has no effect on the ATPase activity. The long term inactivation by ADP and Nb-S6ITP is inhibited at higher inhibitor concentrations according to a kinetics analogous to a substrate excess inhibition. Evidence is presented indicating that the mechanism of ATP hydrolysis by F1 and the long term inactivation by ADP or Nb-S6ITP are related processes. The mechanism of long term inactivation by AMP-P(NH)P appears to be different from that of ADP or Nb-S6ITP.

Adenosine Diphosphate↗
PubMed1978

Immunological properties of membrane-bound adenosine triphosphatase: immunological identification of rutamycin-sensitive F0.F1ATPase from Micrococcus luteus ATCC 4698 established by crossed immunoelectrophoresis.

(1) F0.F1ATPase (EC 3.6.1.3) from Micrococcus luteus ATCC 4698 was solubilized from plasma membranes by the non-ionic detergent Triton X-100 in the presence of 0.05 M MgCl2. (2) The antibiotics rutamycin, Dio-9, quercetin, oligomycin, botrycidin, efrapeptin, leucinostatin, valinomycin, and venturicidin as well as N,N'-dicyclohexylcarbodiimide and dinitrophenol are potent inhibitors of F0.F1ATPase activity.(3) F0.F1ATPase activity is completely inhibited by anti-F1ATPase antibodies. The inhibition is non-competitive. (4) Crossed immunoelectrophoresis reveals a reaction of immunological identity of F0.F1ATPase and F1ATPase indicating that both enzymes have in common antigenic sites.

Adenosine Triphosphatases↗
PubMed1978

Synthesis and properties of 8-azido-1, N6-etheno adenosine triphosphate--a fluorescent and photosensitive ATP analog.

8-Azido-1,N6-etheno-ATP--a fluorescent and photoreactive ATP analog has been synthesized and characterized by elementary analysis, thin layer chromatography, infrared spectroscopy, proton resonance spectroscopy, UV absorption spectroscopy, and fluorescence spectroscopy. The photolytical decomposition upon irradiation at different pH values is tested.

Adenosine Triphosphate↗