scholarly journals Chain lengths of the oligodeoxyribonucleotides formed by the nucleoside triphosphate-dependent deoxyribonuclease of Mycobacterium smegmatis

1970 ◽  
Vol 119 (3) ◽  
pp. 25P-26P ◽  
Author(s):  
F G Winder ◽  
M Lavin
Keyword(s):  
Mycobacterium Smegmatis ◽  
Nucleoside Triphosphate ◽  
Chain Lengths

scholarly journals A nucleoside triphosphate-dependent deoxyribonucleic acid-breakdown system in Mycobacterium smegmatis, and the effect of iron limitation on the activity of this system

1969 ◽  
Vol 111 (5) ◽  
pp. 679-687 ◽  
Author(s):  
F. G. Winder ◽  
M. P. Coughlan
Keyword(s):  
Dna Content ◽  
Mycobacterium Smegmatis ◽  
Deoxyribonucleic Acid ◽  
Maximal Activity ◽  
Enzyme Concentration ◽  
Iron Limitation ◽  
Nucleoside Triphosphate ◽  
Primary Products ◽  
Rate Of Reaction ◽  
Optimum Ph

1. The presence of a nucleoside triphosphate-dependent DNA-breakdown system was demonstrated in extracts of Mycobacterium smegmatis. Its activity was increased substantially by iron limitation, apparently after the fall in DNA content that took place under these conditions. A maximal activity of about 0·2μmole of deoxyribonucleotide/30min./mg. of protein was found in crude extracts. 2. After slight purification by streptomycin treatment, the enzyme showed maximal activity with undenatured DNA (Km≃200μg./ml.), ATP (Km≃1·2mm) or UTP, CTP and GTP giving lower activity and pyrophosphate giving none, and Mg2+ ions (optimum concn. 12mm). The optimum pH was 8·5. 3. In the assay system there was proportionality between enzyme concentration and rate of reaction, but the rate fell off with time. 4. ATP was broken down in the reaction and monodeoxy-ribonucleotides were among the products, but the presence of some oligodeoxy-ribonucleotides was not excluded and the degree of phosphorylation of the primary products was uncertain.

Virtual screening of potential therapeutic inhibitors against spike, helicase and polymerase of SARS-CoV-2 (COVID-19)

Coronaviruses ◽  
2020 ◽  
Vol 01 ◽  
Author(s):  
Ayesha Tazeen ◽  
Farah Deeba ◽  
Aftab Alam ◽  
Rafat Ali ◽  
Romana Ishrat ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Nigella Sativa ◽  
Therapeutic Option ◽  
Natural Compounds ◽  
Host Cells ◽  
Nucleoside Triphosphate ◽  
Symptomatic Management ◽  
Replication Inhibitor ◽  
Inhibitory Potential ◽  
Approved Drugs

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected around 13 million people and has caused more than 5.7 lakh deaths worldwide since December 2019. In the absence of FDA approved drug for its treatment, only symptomatic management is done. Methods: We attempted to uncover potential therapeutic targets of spike, helicase and RNA dependent RNA polymerase (RdRp) proteins of the SARS-CoV-2 employing computational approach. The PDB structure of spike and RdRp and predicted structure of helicase proteins were docked with 100 approved antiviral drugs, natural compounds and some other chemical compounds. Results: The anti-SARS ligands EK1 and CID_23631927, and NCGC00029283 are potential entry inhibitor as it showed affinity with immunogenic receptor binding domain (RBD) of spike protein. This RBD interacts with angiotensin converting enzyme (ACE2) receptor facilitating the entry of virion in the host cells. The FDA approved drugs including Nelfinavir, Saquinavir, Tipranavir, Setrobuvir, Indinavir and Atazanavir showed potential inhibitory activity against targeted domains and thus may act as entry or replication inhibitor or both. Furthermore, several anti-HCoV natural compounds including Amentoflavone, Rutin and Tannin are also potential entry and replication inhibitor as they showed affinity with RBD, Ploop containing nucleoside triphosphate hydrolase and catalytic domain of the respective protein. Dithymoquinone showed significant inhibitory potential against the fusion peptide of S2 domain. Importantly, Tannin, Dithymoquinone and Rutin can be extracted from Nigella sativa seeds and thus may prove to be one of the most potential anti-SARS-CoV-2 inhibitor. Conclusion: Several potential ligands were identified with already known anti-HCoVs activities. Furthermore, as our study showed that some of the ligands acted as both entry or replication inhibitor against SARS-CoV-2, it is envisaged that a combination of either inhibitors with a dual mode of action would prove to be a much desired therapeutic option against this viral infection.

A Monte Carlo Study of Flexible Polymer Chain Conformations in Restricted Volumes. I. A Model for Insoluble Blocks Conformations in Swollen Cores of Multimolecular Spherical Block Copolymer Micelles

1993 ◽  
Vol 58 (10) ◽  
pp. 2290-2304 ◽  
Author(s):  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Monte Carlo ◽  
Block Copolymer ◽  
Monte Carlo Study ◽  
Volume Effect ◽  
Micellar Systems ◽  
Flexible Polymer ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Chain Conformations ◽  
Chain Lengths

Monte Carlo simulations of chain conformations in a restricted spherical volume at relatively high densities of segments were performed for various numbers of chains, N, and chain lengths (number of segments), L, on a tetrahedral lattice. All chains are randomly end-tethered to the surface of the sphere. A relatively uniform surface density of the tethered ends is guaranteed in our simulations. A simultaneous self-avoiding walk of all chains creates starting conformations for a subsequent equilibration. A modified algorithm similar to that of Siepmann and Frenkel is used for the equilibration of the chain conformations. In this paper, only a geometrical excluded volume effect of segments is considered. Various structural and conformational characteristics, e.g. segment densities gS(r), free end densities gF(r) as functions of the position in the sphere (a distance from the center), distributions of the tethered-to-free end distances, ρTF(rTF), etc. are calculated and their physical meaning is discussed. The model is suitable for studies of chain conformations is swollen cores of multimolecular block copolymer micelles and for interpretation of non-radiative excitation energy migration in polymeric micellar systems.

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