scholarly journals Intrinsic contributions of polar amino acid residues toward thermal stability of an ABC-ATPase of mesophilic origin

2003 ◽  
Vol 12 (9) ◽  
pp. 2118-2120 ◽  
Author(s):  
Jyoti Sarin ◽  
Gajendra P.S. Raghava ◽  
Pradip K. Chakraborti
Keyword(s):  
Thermal Stability ◽  
Amino Acid ◽  
Amino Acid Residues ◽  
Polar Amino Acid ◽  
Thermal Stability Of

scholarly journals Engineering Improves Enzymatic Synthesis of L-Tryptophan by Tryptophan Synthase from Escherichia coli

2020 ◽  
Vol 8 (4) ◽  
pp. 519
Author(s):  
Lisheng Xu ◽  
Fangkai Han ◽  
Zeng Dong ◽  
Zhaojun Wei
Keyword(s):  
Thermal Stability ◽  
Amino Acid ◽  
Directed Evolution ◽  
Amino Acid Residue ◽  
Rational Design ◽  
Molecular Engineering ◽  
Mutant Enzyme ◽  
Tryptophan Synthase ◽  
Mutant Library ◽  
Thermal Stability Of

To improve the thermostability of tryptophan synthase, the molecular modification of tryptophan synthase was carried out by rational molecular engineering. First, B-FITTER software was used to analyze the temperature factor (B-factor) of each amino acid residue in the crystal structure of tryptophan synthase. A key amino acid residue, G395, which adversely affected the thermal stability of the enzyme, was identified, and then, a mutant library was constructed by site-specific saturation mutation. A mutant (G395S) enzyme with significantly improved thermal stability was screened from the saturated mutant library. Error-prone PCR was used to conduct a directed evolution of the mutant enzyme (G395S). Compared with the parent, the mutant enzyme (G395S /A191T) had a Km of 0.21 mM and a catalytic efficiency kcat/Km of 5.38 mM−1∙s−1, which was 4.8 times higher than that of the wild-type strain. The conditions for L-tryptophan synthesis by the mutated enzyme were a L-serine concentration of 50 mmol/L, a reaction temperature of 40 °C, pH of 8, a reaction time of 12 h, and an L-tryptophan yield of 81%. The thermal stability of the enzyme can be improved by using an appropriate rational design strategy to modify the correct site. The catalytic activity of tryptophan synthase was increased by directed evolution.

scholarly journals New Anti SARS-Cov-2 Targets for Quinoline Derivatives Chloroquine and Hydroxychloroquine

2020 ◽  
Vol 21 (16) ◽  
pp. 5856
Author(s):  
Davide Gentile ◽  
Virginia Fuochi ◽  
Antonio Rescifina ◽  
Pio Maria Furneri
Keyword(s):  
Hydrogen Bonding ◽  
Amino Acid ◽  
Hydroxyl Group ◽  
Simulation Methods ◽  
Quinoline Derivatives ◽  
Amino Acid Residues ◽  
Polar Amino Acid ◽  
Health Crisis ◽  
E Protein ◽  
Rapid Spread

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a severe global health crisis. In this paper, we used docking and simulation methods to identify potential targets and the mechanism of action of chloroquine (CQ) and hydroxychloroquine (HCQ) against SARS-CoV-2. Our results showed that both CQ and HCQ influenced the functionality of the envelope (E) protein, necessary in the maturation processes of the virus, due to interactions that modify the flexibility of the protein structure. Furthermore, CQ and HCQ also influenced the proofreading and capping of viral RNA in SARS-CoV-2, performed by nsp10/nsp14 and nsp10/nsp16. In particular, HCQ demonstrated a better energy binding with the examined targets compared to CQ, probably due to the hydrogen bonding of the hydroxyl group of HCQ with polar amino acid residues.

Functional analysis of polar amino-acid residues in membrane associated regions of the NHE1 isoform of the mammalian Na+ /H+ exchanger

2001 ◽  
Vol 268 (17) ◽  
pp. 4674-4685 ◽  
Author(s):  
Rakhilya Murtazina ◽  
Brenda J. Booth ◽  
Bonnie L. Bullis ◽  
Dyal N. Singh ◽  
Larry Fliegel
Keyword(s):  
Functional Analysis ◽  
Amino Acid ◽  
Amino Acid Residues ◽  
Polar Amino Acid

scholarly journals Functional role of polar amino acid residues in Na+/H+ exchangers

2001 ◽  
Vol 357 (1) ◽  
pp. 1 ◽  
Author(s):  
Christine A. WIEBE ◽  
Emily R. DiBATTISTA ◽  
Larry FLIEGEL
Keyword(s):  
Amino Acid ◽  
Functional Role ◽  
Amino Acid Residues ◽  
Polar Amino Acid
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