Determination of the Stereochemistry of C-2’ and C-3’ Positions of Taxine NA-1 (2’-Hydroxytaxine II) by the Asymmetric Synthesis of the Reductive Degradation Product of Its Side Chain Moiety

Heterocycles ◽  
2012 ◽  
Vol 85 (7) ◽  
pp. 1697 ◽  
Author(s):  
Wanxia Tang ◽  
Masayoshi Ando ◽  
Hiroshi Minato ◽  
Mariko Ando
Keyword(s):  
Asymmetric Synthesis ◽  
Degradation Product ◽  
Side Chain ◽  
Reductive Degradation

Determination of the Relative and Absolute Configuration of the Dimethylmyristoyl Side Chain of Pneumocandin B0by Asymmetric Synthesis

2002 ◽  
Vol 4 (24) ◽  
pp. 4201-4204 ◽  
Author(s):  
William R. Leonard, ◽  
Kevin M. Belyk ◽  
Dean R. Bender ◽  
David A. Conlon ◽  
David L. Hughes ◽  
...  
Keyword(s):  
Asymmetric Synthesis ◽  
Absolute Configuration ◽  
Side Chain

Polypeptides Folding: Rules for the Calculation of the Backbone Dihedral Angles φ starting from the Amino Acid Sequence

2020 ◽  
Author(s):  
Michele Larocca
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Theoretical Approach ◽  
Polypeptide Chain ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Dihedral Angles ◽  
Mechanical Forces ◽  
Specific Chemical

<p>Protein folding is strictly related to the determination of the backbone dihedral angles and depends on the information contained in the amino acid sequence as well as on the hydrophobic effect. To date, the type of information embedded in the amino acid sequence has not yet been revealed. The present study deals with these problematics and aims to furnish a possible explanation of the information contained in the amino acid sequence, showing and reporting rules to calculate the backbone dihedral angles φ. The study is based on the development of mechanical forces once specific chemical interactions are established among the side chain of the residues in a polypeptide chain. It aims to furnish a theoretical approach to predict backbone dihedral angles which, in the future, may be applied to computational developments focused on the prediction of polypeptide structures.</p>

scholarly journals Validated spectral manipulations for determination of an anti-neoplastic drug and its related impurities including its hazardous degradation product

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21332-21342
Author(s):  
Ibrahim A. Naguib ◽  
Eglal A. Abdelaleem ◽  
Eman S. Hassan ◽  
Aml A. Emam
Keyword(s):  
Absorption Spectra ◽  
Degradation Product ◽  
Zero Order ◽  
Sterile Water ◽  
Related Impurities ◽  
Amino Imidazole

Zero order absorption spectra of 12 μg mL−1 of Dacarbazine (), 5-amino-imidazole-4 carboxamide (), and 2-azahypoxanthine (…) using sterile water as a blank.

scholarly journals Investigation of the Anti-Methicillin-Resistant Staphylococcus aureus Activity of (+)-Tanikolide- and (+)-Malyngolide-Based Analogues Prepared by Asymmetric Synthesis

2021 ◽  
Vol 22 (12) ◽  
pp. 6400
Author(s):  
Joseph Breheny ◽  
Cian Kingston ◽  
Robert Doran ◽  
Joao Anes ◽  
Marta Martins ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Asymmetric Synthesis ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Antimicrobial Properties ◽  
Side Chain ◽  
Alkyl Side Chain ◽  
Methicillin Resistant ◽  
Antibacterial And Antifungal

Herein, we report antibacterial and antifungal evaluation of a series of previously prepared (+)-tanikolide analogues. One analogue, (4S,6S)-4-methyltanikolide, displayed promising anti-methicillin-resistant Staphylococcus aureus activity with a MIC of 12.5 µg/mL. Based on the antimicrobial properties of the structurally related (−)-malyngolide, two further analogues (4S,6S)-4-methylmalyngolide and (4R,6S)-4-methylmalyngolide bearing a shortened n-nonyl alkyl side chain were prepared in the present study using a ZrCl4-catalysed deprotection/cyclisation as the key step in their asymmetric synthesis. When these were tested for activity against anti-methicillin-resistant Staphylococcus aureus, the MIC increased to 50 µg/mL.

scholarly journals Second derivative synchronous fluorescence determination of avanafil in the presence of its acid-induced degradation product aided by powerful Lean Six Sigma tools augmented with D-optimal design

RSC Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 3834-3842
Author(s):  
Khalid A. M. Attia ◽  
Ahmad A. Mohamad ◽  
Mohamed S. Emara ◽  
Ahmed M. Abdel-Raoof ◽  
Mohamed A. Hasan ◽  
...  
Keyword(s):  
Optimal Design ◽  
Quantitative Determination ◽  
Degradation Product ◽  
Six Sigma ◽  
Lean Six Sigma ◽  
Synchronous Fluorescence ◽  
Second Derivative ◽  
Fluorescence Determination ◽  
Spectrofluorimetric Method

In this work, the quantitative determination of an erectile dysfunctional drug avanafil in the presence of its acid-induced degradation product was achieved via the application of a pre-optimized novel spectrofluorimetric method.

scholarly journals Gating Competence of Constitutively Open CLC-0 Mutants Revealed by the Interaction with a Small Organic Inhibitor

2003 ◽  
Vol 122 (3) ◽  
pp. 295-306 ◽  
Author(s):  
Sonia Traverso ◽  
Laura Elia ◽  
Michael Pusch
Keyword(s):  
Chloride Channels ◽  
Bound State ◽  
Side Chain ◽  
Pore Channel ◽  
Kinetic Properties ◽  
Wild Type ◽  
High Affinity ◽  
Critical Residue ◽  
Fast Gating

Opening of CLC chloride channels is coupled to the translocation of the permeant anion. From the recent structure determination of bacterial CLC proteins in the closed and open configuration, a glutamate residue was hypothesized to form part of the Cl−-sensitive gate. The negatively charged side-chain of the glutamate was suggested to occlude the permeation pathway in the closed state, while opening of a single protopore of the double-pore channel would reflect mainly a movement of this side-chain toward the extracellular pore vestibule, with little rearrangement of the rest of the channel. Here we show that mutating this critical residue (Glu166) in the prototype Torpedo CLC-0 to alanine, serine, or lysine leads to constitutively open channels, whereas a mutation to aspartate strongly slowed down opening. Furthermore, we investigated the interaction of the small organic channel blocker p-chlorophenoxy-acetic acid (CPA) with the mutants E166A and E166S. Both mutants were strongly inhibited by CPA at negative voltages with a &gt;200-fold larger affinity than for wild-type CLC-0 (apparent KD at −140 mV ∼4 μM). A three-state linear model with an open state, a low-affinity and a high-affinity CPA-bound state can quantitatively describe steady-state and kinetic properties of the CPA block. The parameters of the model and additional mutagenesis suggest that the high-affinity CPA-bound state is similar to the closed configuration of the protopore gate of wild-type CLC-0. In the E166A mutant the glutamate side chain that occludes the permeation pathway is absent. Thus, if gating consists only in movement of this side-chain the mutant E166A should not be able to assume a closed conformation. It may thus be that fast gating in CLC-0 is more complex than anticipated from the bacterial structures.

Asymmetric Synthesis of Sesaminone:  Confirmation of Its Structure and Determination of Its Absolute Configuration

1997 ◽  
Vol 62 (21) ◽  
pp. 7413-7417 ◽  
Author(s):  
Andrew T. Maioli ◽  
Rita L. Civiello ◽  
Bruce M. Foxman ◽  
Dana M. Gordon
Keyword(s):  
Asymmetric Synthesis ◽  
Absolute Configuration
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