scholarly journals PEG-chitosan branched copolymers to improve the biocatalytic properties of erwinia carotovora recombinant L-asparaginase

2015 ◽  
Vol 61 (4) ◽  
pp. 480-487 ◽  
Author(s):  
E.V. Kudryashova ◽  
K.V. Suhoverkov ◽  
N.N. Sokolov
Keyword(s):  
Catalytic Properties ◽  
Catalytic Efficiency ◽  
Erwinia Carotovora ◽  
Antitumor Agent ◽  
Amide Bond ◽  
The Novel ◽  
Amino Groups ◽  
Characteristic Absorption Band ◽  
New Approach ◽  
Pharmacokinetic Properties

A new approach to the regulation of catalytic properties of medically relevant enzymes has been proposed using the novel recombinant preparation of L-asparaginase from Erwinia carotovora (EwA), a promising antitumor agent. New branched co-polymers of different composition based on chitosan modified with polyethylene glycol (PEG) molecules, designated as PEG-chitosan, have been synthesized. PEG-chitosan copolymers were further conjugated with EwA. In order to optimize the catalytic properties of asparaginase two types of conjugates differing in their architecture have been synthesized: (1) crown-type conjugates were synthesized by reductive amination reaction between the reducing end of the PEG-chitosan copolymer and enzyme amino groups; (2) multipoint-conjugates were synthesized using the reaction of multipoint amide bond formation between PEG-chitosan amino groups and carboxyl groups of the enzyme in the presence of the Woodward’s reagent. The structure and composition of these conjugates were determined by IR spectroscopy. The content of the copolymers in the conjugates was controlled by the characteristic absorption band of C-O-C bonds in the PEG structure at the frequency of 1089 cm-1. The study of catalytic characteristics of EwA preparations by conductometry showed that at physiological pH values the enzyme conjugates with PEG-chitosan with optimized structure and the optimal composition demonstrated 5-8-fold higher catalytic efficiency (kcat/Km) than the native enzyme. To certain extent, this can be attributed to favorable shift of pH-optima in result of positively charged amino-groups introduction in the vicinity of the active site. The proposed approach, chito-pegylation, is effective for regulating the catalytic and pharmacokinetic properties of asparaginase, and is promising for the development of prolonged action dosage forms for other enzyme therapeutics

scholarly journals Catalytic properties of class A β-lactamases: efficiency and diversity

1998 ◽  
Vol 330 (2) ◽  
pp. 581-598 ◽  
Author(s):  
André MATAGNE ◽  
Josette LAMOTTE-BRASSEUR ◽  
Jean-Marie FRÈRE
Keyword(s):  
Structural Changes ◽  
Bacterial Resistance ◽  
Catalytic Properties ◽  
Point Mutations ◽  
Catalytic Efficiency ◽  
Amide Bond ◽  
X Ray Crystallography ◽  
Class A ◽  
New Genes ◽  
Lactam Ring

β-Lactamases are the main cause of bacterial resistance to penicillins, cephalosporins and related β-lactam compounds. These enzymes inactivate the antibiotics by hydrolysing the amide bond of the β-lactam ring. Class A β-lactamases are the most widespread enzymes and are responsible for numerous failures in the treatment of infectious diseases. The introduction of new β-lactam compounds, which are meant to be ‘β-lactamase-stable’ or β-lactamase inhibitors, is thus continuously challenged either by point mutations in the ubiquitous TEM and SHV plasmid-borne β-lactamase genes or by the acquisition of new genes coding for β-lactamases with different catalytic properties. On the basis of the X-ray crystallography structures of several class A β-lactamases, including that of the clinically relevant TEM-1 enzyme, it has become possible to analyse how particular structural changes in the enzyme structures might modify their catalytic properties. However, despite the many available kinetic, structural and mutagenesis data, the factors explaining the diversity of the specificity profiles of class A β-lactamases and their amazing catalytic efficiency have not been thoroughly elucidated. The detailed understanding of these phenomena constitutes the cornerstone for the design of future generations of antibiotics.

Coupling of Steroid O-(Carboxymethyl)oxime Derivatives with Single-Protected α,ω-Diaminoalkanes

1999 ◽  
Vol 64 (12) ◽  
pp. 2035-2043 ◽  
Author(s):  
Vladimír Pouzar ◽  
Ivan Černý ◽  
Pavel Drašar
Keyword(s):  
Trifluoroacetic Acid ◽  
Protecting Groups ◽  
Oxime Group ◽  
Amino Groups ◽  
New Approach ◽  
Terminal Amino ◽  
Oxime Derivatives

New approach to the synthesis of steroid oximes bearing O-substituents with terminal amino groups was described. The easily accessible steroid O-(carboxymethyl)oximes were reacted with single-protected Boc-α,ω-diaminoalkanes to give corresponding amide intermediates. From them the Boc protecting groups were cleaved with trifluoroacetic acid to afford the desired steroid derivatives with terminal amino groups. The procedure was succesfully tested on steroids with O-(carboxymethyl)oxime group in positions 7 and 17. The decomposition of target products was observed during deprotection of substituted 19-oximes.

scholarly journals New Approach in the Application of Conjugated Polymers: The Light-Activated Source of Versatile Singlet Oxygen Molecule

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1098
Author(s):  
Agata Blacha-Grzechnik
Keyword(s):  
Conjugated Polymers ◽  
Singlet Oxygen ◽  
Near Infrared ◽  
Photophysical Properties ◽  
Short Review ◽  
The Novel ◽  
New Approach ◽  
Intermolecular Energy ◽  
Intermolecular Energy Transfer ◽  
High Absorption

For many years, the research on conjugated polymers (CPs) has been mainly focused on their application in organic electronics. Recent works, however, show that due to the unique optical and photophysical properties of CPs, such as high absorption in UV–Vis or even near-infrared (NIR) region and efficient intra-/intermolecular energy transfer, which can be relatively easily optimized, CPs can be considered as an effective light-activated source of versatile and highly reactive singlet oxygen for medical or catalytic use. The aim of this short review is to present the novel possibilities that lie dormant in those exceptional polymers with the extended system of π-conjugated bonds.

A monovacant heteropolytungstate-incorporated trimeric carbonyl rhenium cluster, [(AsW11O39){Re(CO)3}3(μ3-OH)(μ2-OH)]6−: synthesis, structure and catalytic properties

RSC Advances ◽  
2014 ◽  
Vol 4 (55) ◽  
pp. 28848-28851 ◽  
Author(s):  
Yanhui Zhang ◽  
Dongdi Zhang ◽  
Zhiyuan Huo ◽  
Pengtao Ma ◽  
Jingyang Niu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Selectivity ◽  
Catalytic Properties ◽  
The Novel ◽  
Rhenium Cluster

The novel undecatungstoarsenate-supported carbonyl rhenium derivative exhibits prominent catalytic activity and high selectivity in the cycloaddition of epoxides.

Pharmaceutical development of a parenteral lyophilized formulation of the novel indoloquinone antitumor agent EO9

1994 ◽  
Vol 34 (5) ◽  
pp. 416-422 ◽  
Author(s):  
Jantine D. Jonkman-de Vries ◽  
Herre Talsma ◽  
Roland E. C. Henrar ◽  
Jantien J. Kettenes-van den Bosch ◽  
Auke Bult ◽  
...  
Keyword(s):  
Antitumor Agent ◽  
The Novel ◽  
Pharmaceutical Development ◽  
Lyophilized Formulation

Mobility-as-a-Service: Simulation of Multi-Modal Operations in Low-Density Cities

2021 ◽  
pp. 036119812110398
Author(s):  
Mohamed El-Agroudy ◽  
Hatem Abou-Senna ◽  
Essam Radwan
Keyword(s):  
Performance Measures ◽  
Magic Bullet ◽  
Low Density ◽  
The Novel ◽  
Review Of The Literature ◽  
Modal Interactions ◽  
New Approach ◽  
Novel Interactions ◽  
Alternative Scenarios ◽  
Urban Characteristics

In the case of the low-density city, empirical evidence continuously demonstrates that transit investment is not a magic bullet. Desirable outcomes are not guaranteed and are often dependent on development density and other urban characteristics. Mobility-as-a-service (MaaS) presents a new approach: a digital platform providing access to multi-modal travel alternatives and totally comprehensive integrated trip-making, planning, and payment services. Review of the literature highlights shortcomings in traditional transportation planning by examining aspects of multi-modal planning such as adoption, parterships, operations, integration, capacity implications, and impact analyses. To enhance the practice of multi-modal planning, the following experiment evaluates various performance measures and inter-modal interactions on International Drive in Orlando, Florida, U.S., via D- and I-optimal experimental designs in a simulated MaaS network. Alternative scenarios are developed comparing varied modal shares across five travel modes: personal vehicles, transit, ridesourcing (or ride-hailing), micro-mobility, and walking. The modal effects are analyzed to highlight the strengths and weakness of each mode under a variety of congestion conditions. While transit enjoys the lowest impact per person, ridesourcing demonstrates adverse effects across all measures. Based on the novel interactions of transit and ridesourcing with directional demand, strategies are outlined for optimizing ridesourcing-transit integration to reduce route travel time, queuing, and overall network delay. The performance impacts of curbside facilities are also discussed for improved multi-modal integration at the street level. These findings are applied to propose a framework for effective planning and implementation of mobility services in low-density cities, focused on operations, city-level connectivity, and curbside management.

scholarly journals Application of fungal copper carbonate nanoparticles as environmental catalysts: organic dye degradation and chromate removal

Microbiology ◽  
2021 ◽  
Vol 167 (12) ◽  
Author(s):  
Feixue Liu ◽  
Dinesh Singh Shah ◽  
Laszlo Csetenyi ◽  
Geoffrey Michael Gadd
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Dye Degradation ◽  
Antibacterial Properties ◽  
Toxic Metal ◽  
Catalytic Efficiency ◽  
Methyl Red ◽  
Copper Carbonate ◽  
Wide Range ◽  
Organic Dye Degradation

Biomineralization is a ubiquitous process in organisms to produce biominerals, and a wide range of metallic nanoscale minerals can be produced as a consequence of the interactions of micro-organisms with metals and minerals. Copper-bearing nanoparticles produced by biomineralization mechanisms have a variety of applications due to their remarkable catalytic efficiency, antibacterial properties and low production cost. In this study, we demonstrate the biotechnological potential of copper carbonate nanoparticles (CuNPs) synthesized using a carbonate-enriched biomass-free ureolytic fungal spent culture supernatant. The efficiency of the CuNPs in pollutant remediation was investigated using a dye (methyl red) and a toxic metal oxyanion, chromate Cr(VI). The biogenic CuNPs exhibited excellent catalytic properties in a Fenton-like reaction to degrade methyl red, and efficiently removed Cr(VI) from solution due to both adsorption and reduction of Cr(VI). X-ray photoelectron spectroscopy (XPS) identified the oxidation of reducing Cu species of the CuNPs during the reaction with Cr(VI). This work shows that urease-positive fungi can play an important role not only in the biorecovery of metals through the production of insoluble nanoscale carbonates, but also provides novel and simple strategies for the preparation of sustainable nanomineral products with catalytic properties applicable to the bioremediation of organic and metallic pollutants, solely and in mixtures.

Synthesis, Characterization and Catalytic Properties of the Novel Manganese-Containing Amorphous Mesoporous Material MnTUD-1

2008 ◽  
Vol 112 (19) ◽  
pp. 7468-7476 ◽  
Author(s):  
Anand Ramanathan ◽  
Tanja Archipov ◽  
Rajamanickam Maheswari ◽  
Ulf Hanefeld ◽  
Emil Roduner ◽  
...  
Keyword(s):  
Mesoporous Material ◽  
Catalytic Properties ◽  
The Novel
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