scholarly journals The dye-linked alcohol dehydrogenase of Rhodopseudomonas acidophila. Comparison with dye-linked methanol dehydrogenases

1978 ◽  
Vol 169 (3) ◽  
pp. 677-686 ◽  
Author(s):  
C W Bamforth ◽  
J R Quayle
Keyword(s):  
Alcohol Dehydrogenase ◽  
Aliphatic Amines ◽  
Primary Alcohols ◽  
Ph Optimum ◽  
Rhodopseudomonas Acidophila ◽  
Wide Range ◽  
The Stability ◽  
Phenazine Methosulphate ◽  
Primary Aliphatic Amines

1. A dye-linked alcohol dehydrogenase was purified 20-fold from extracts of Rhodopseudomonas acidophila 10050 grown anaerobically in the light on methanol/HCO3-. 2. The enzyme resembled many previously reported methanol dehydrogenases from other methylotrophic organisms in coupling to phenazine methosulphate, requiring ammonia as an activator, possessing a pH optimum of 9 and a mol.wt. of approx. 116000. In many other respects the enzyme showed singular properties. 3. The stability of the enzyme under various conditions of temperature and pH was studied. 4. Primary aliphatic amines containing up to nine carbon atoms (the longest tested) were better activators than ammonia. 5. A wide range of primary alcohols and aldehydes served as substrates, with apparent Km values ranging from 57 mM for methanol to 6 micron for ethanol. 6. O2 was an inhibitor competitive with respect to the alcohol substrate. In the presence of O2, apparent Km values of 145 mM were recorded for methanol. 6. Cyanide and alphaalpha'-bipyridine were inhibitors competitive with respect to the amine activator. 7. The properties of the enzyme from Rhodopseudomonas acidophila are compared with those of similar enzymes from other organisms, and implications of the salient differences are discussed.

scholarly journals Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase

1978 ◽  
Vol 173 (2) ◽  
pp. 483-496 ◽  
Author(s):  
C S Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Substrate Inhibition ◽  
Kinetic Studies ◽  
Primary Alcohols ◽  
Reductive Methylation ◽  
Factors Affecting ◽  
Liver Alcohol Dehydrogenase ◽  
Wide Range ◽  
Lysine Residues ◽  
Michaelis Constants

Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.

Efficient One-Step Conversion of Primary Aliphatic Amines into Primary Alcohols:  Application to a Model Study for the Total Synthesis of (±)-Scopadulin

2000 ◽  
Vol 2 (18) ◽  
pp. 2893-2895 ◽  
Author(s):  
S. M. Abdur Rahman ◽  
Hiroaki Ohno ◽  
Naoyoshi Maezaki ◽  
Chuzo Iwata ◽  
Tetsuaki Tanaka
Keyword(s):  
Total Synthesis ◽  
Aliphatic Amines ◽  
Primary Alcohols ◽  
Model Study ◽  
One Step ◽  
Primary Aliphatic Amines

Performance of Electronic Structure Methods for the Description of Hückel-Möbius Interconversions in Extended π-Systems

2019 ◽  
Author(s):  
Tatiana Woller ◽  
Ambar Banerjee ◽  
Nitai Sylvetsky ◽  
Xavier Deraet ◽  
Frank De Proft ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Basis Set ◽  
Dft Methods ◽  
Molecular Switching ◽  
Wide Range ◽  
Electronic Structure Methods ◽  
Explicitly Correlated ◽  
Relative Errors ◽  
The Stability ◽  
Basis Set Expansion

<p>Expanded porphyrins provide a versatile route to molecular switching devices due to their ability to shift between several π-conjugation topologies encoding distinct properties. Taking into account its size and huge conformational flexibility, DFT remains the workhorse for modeling such extended macrocycles. Nevertheless, the stability of Hückel and Möbius conformers depends on a complex interplay of different factors, such as hydrogen bonding, p···p stacking, steric effects, ring strain and electron delocalization. As a consequence, the selection of an exchange-correlation functional for describing the energy profile of topological switches is very difficult. For these reasons, we have examined the performance of a variety of wavefunction methods and density functionals for describing the thermochemistry and kinetics of topology interconversions across a wide range of macrocycles. Especially for hexa- and heptaphyrins, the Möbius structures have a pronouncedly stronger degree of static correlation than the Hückel and figure-eight structures, and as a result the relative energies of singly-twisted structures are a challenging test for electronic structure methods. Comparison of limited orbital space full CI calculations with CCSD(T) calculations within the same active spaces shows that post-CCSD(T) correlation contributions to relative energies are very minor. At the same time, relative energies are weakly sensitive to further basis set expansion, as proven by the minor energy differences between MP2/cc-pVDZ and explicitly correlated MP2-F12/cc-pVDZ-F12 calculations. Hence, our CCSD(T) reference values are reasonably well-converged in both 1-particle and n-particle spaces. While conventional MP2 and MP3 yield very poor results, SCS-MP2 and particularly SOS-MP2 and SCS-MP3 agree to better than 1 kcal mol<sup>-1</sup> with the CCSD(T) relative energies. Regarding DFT methods, only M06-2X provides relative errors close to chemical accuracy with a RMSD of 1.2 kcal mol<sup>-1</sup>. While the original DSD-PBEP86 double hybrid performs fairly poorly for these extended p-systems, the errors drop down to 2 kcal mol<sup>-1</sup> for the revised revDSD-PBEP86-NL, again showing that same-spin MP2-like correlation has a detrimental impact on performance like the SOS-MP2 results. </p>

Exogenous Directing Group Free, Ligand-Enabled gamma-C(sp3)–H Arylation of Free Primary Aliphatic Amines and α-Amino Esters

2019 ◽  
Author(s):  
Yongzheng Ding ◽  
Shuai Fan ◽  
Xiaoxi Chen ◽  
yuzhen gao ◽  
Gang Li
Keyword(s):  
Amino Acids ◽  
Large Scale ◽  
Free Ligand ◽  
Aliphatic Amines ◽  
Rapid Synthesis ◽  
Amino Esters ◽  
Directing Group ◽  
Large Scale Synthesis ◽  
Primary Aliphatic Amines

A Pdᴵᴵ-catalyzed, ligand-enabled gamma-C(sp3)–H arylation of free primary aliphatic amines and amino esters without using an exogenous directing group is reported. This reaction is compatible with unhindered free aliphatic amines, and it is also be applicable to the rapid synthesis of biologically and synthetically valuable unnatural α-amino acids. Large scale synthesis is also feasible using this method.<br>

Insights into Potent Therapeutical Antileukemic Agent L-glutaminase Enzyme Under Solid-state Fermentation: A Review

2020 ◽  
Vol 21 (3) ◽  
pp. 211-220 ◽  
Author(s):  
Chandrasai Potla Durthi ◽  
Madhuri Pola ◽  
Satish Babu Rajulapati ◽  
Anand Kishore Kola
Keyword(s):  
Solid State ◽  
Solid State Fermentation ◽  
Food Industry ◽  
Energy Requirement ◽  
Production Studies ◽  
Wide Range ◽  
Hybridoma Technology ◽  
Bacteria And Fungi ◽  
The Stability ◽  
Glutaminase Activity

Aim & objective: To review the applications and production studies of reported antileukemic drug L-glutaminase under Solid-state Fermentation (SSF). Overview: An amidohydrolase that gained economic importance because of its wide range of applications in the pharmaceutical industry, as well as the food industry, is L-glutaminase. The medical applications utilized it as an anti-tumor agent as well as an antiretroviral agent. L-glutaminase is employed in the food industry as an acrylamide degradation agent, as a flavor enhancer and for the synthesis of theanine. Another application includes its use in hybridoma technology as a biosensing agent. Because of its diverse applications, scientists are now focusing on enhancing the production and optimization of L-glutaminase from various sources by both Solid-state Fermentation (SSF) and submerged fermentation studies. Of both types of fermentation processes, SSF has gained importance because of its minimal cost and energy requirement. L-glutaminase can be produced by SSF from both bacteria and fungi. Single-factor studies, as well as multi-level optimization studies, were employed to enhance L-glutaminase production. It was concluded that L-glutaminase activity achieved by SSF was 1690 U/g using wheat bran and Bengal gram husk by applying feed-forward artificial neural network and genetic algorithm. The highest L-glutaminase activity achieved under SSF was 3300 U/gds from Bacillus sp., by mixture design. Purification and kinetics studies were also reported to find the molecular weight as well as the stability of L-glutaminase. Conclusion: The current review is focused on the production of L-glutaminase by SSF from both bacteria and fungi. It was concluded from reported literature that optimization studies enhanced L-glutaminase production. Researchers have also confirmed antileukemic and anti-tumor properties of the purified L-glutaminase on various cell lines.

scholarly journals Polymer-Drug Conjugates as Nanotheranostic Agents

2021 ◽  
Vol 2 (1) ◽  
pp. 63-81
Author(s):  
Sajana Manandhar ◽  
Erica Sjöholm ◽  
Johan Bobacka ◽  
Jessica M. Rosenholm ◽  
Kuldeep K. Bansal
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Treatment Options ◽  
The Body ◽  
Drug Conjugates ◽  
Imaging Characteristics ◽  
Wide Range ◽  
Systemic Side Effects ◽  
Theranostic Agents ◽  
The Stability

Since the last decade, the polymer-drug conjugate (PDC) approach has emerged as one of the most promising drug-delivery technologies owing to several benefits like circumventing premature drug release, offering controlled and targeted drug delivery, improving the stability, safety, and kinetics of conjugated drugs, and so forth. In recent years, PDC technology has advanced with the objective to further enhance the treatment outcomes by integrating nanotechnology and multifunctional characteristics into these systems. One such development is the ability of PDCs to act as theranostic agents, permitting simultaneous diagnosis and treatment options. Theranostic nanocarriers offer the opportunity to track the distribution of PDCs within the body and help to localize the diseased site. This characteristic is of particular interest, especially among those therapeutic approaches where external stimuli are supposed to be applied for abrupt drug release at the target site for localized delivery to avoid systemic side effects (e.g., Visudyne®). Thus, with the help of this review article, we are presenting the most recent updates in the domain of PDCs as nanotheranostic agents. Different methodologies utilized to design PDCs along with imaging characteristics and their applicability in a wide range of diseases, have been summarized in this article.

Pd‐Catalyzed Regio‐ and Stereoselective sp 3 C−H Arylation of Primary Aliphatic Amines: Mechanistic Studies and Synthetic Applications

2021 ◽  
Vol 2021 (7) ◽  
pp. 1136-1145
Author(s):  
Hyeonbin Ha ◽  
Ho Jeong Choi ◽  
Hahyoun Park ◽  
Yunyeong Gwon ◽  
Jiin Lee ◽  
...  
Keyword(s):  
Aliphatic Amines ◽  
Mechanistic Studies ◽  
Primary Aliphatic Amines

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

Oxidation of primary aliphatic amines with sodium perborate

1989 ◽  
Vol 30 (47) ◽  
pp. 6495-6496 ◽  
Author(s):  
Walter W Zajac ◽  
Michael G Darcy ◽  
Amador P Subong ◽  
John H Buzby
Keyword(s):  
Aliphatic Amines ◽  
Sodium Perborate ◽  
Primary Aliphatic Amines
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