China 
Africa 
Explore chapters and articles related to this topic
Functional Proteins
Published in Narendra Pal Singh Chauhan, Functionalized Polymers, 2021
Importantly, the bulk of the polymer-protein conjugates so far reported, including approved products, are synthesized with stable linkages. The primary concern, however, is the preservation of protein activity, which in general is significantly reduced after conjugation, because of steric hindrance provided by polymer strands. Site-directed conjugation most likely can be the best approach to avoid such limitation by targeting a protein surface area far from the activity sites. There were several attempts to use the prodrugs concept to make polymer-protein conjugates in which trigger-based polymer chain in vivo release is intended. In this approach, native protein can regain its activity even if the conjugate loses starting protein activity. Thus, the number of sites of polymer chain coupling is not crucial. The most critical part is fine-tuning of protein kinetics and conjugate clearance for developing a polymer-protein prodrug. We envision that polymer-protein conjugates of site-specific conjugation will be accompanied by further refinement of controlling stability and lability of critical linkages. The future progress of these conjugates will rely significantly on the advancement in synthetic polymers and the understanding of the biochemical aspects of proteins and diseases.
Bioanalytical Methods
Published in Jerome Greyson, Carbon, Nitrogen, and Sulfur Pollutants and Their Determination in Air and Water, 2020
Some enzymes require so-called co-factors to be present for them to exhibit catalytic activity. Co-factors are generally not proteins but may be metal ions or organic molecules. When the co-factor is an organic molecule, it is frequently referred to as a coenzyme. Co-factors may be bound to the protein moiety with varying degrees of strength up to and including covalent binding and, except for the covalently bound ones, they may be removed from the protein by a number of different means as, for example, dialysis. When the bonding is covalent and the co-factor cannot be separated from the protein, it is often called a prosthetic group. The intact enzyme-cofactor entity, regardless of the lability of the co-factor, is called a holoenzyme while the separated precursor protein of an enzyme-coenzyme pairis called an apoenzyme.
Modulated Fields and "Window" Effects
Published in Charles Polk, Elliot Postow, CRC Handbook of Biological Effects of Electromagnetic Fields, 2019
Elliot Poston, Mays L. Swicord
"Windows" are not new to biology. The existence of competing processes can result in a "window". A commonplace example of this phenomenon is the dependence of cell growth on temperature. As temperature increases from the minimum compatible with growth to about 35°C, the growth rate increases monotonically, because the biochemical reactions required for growth proceed more rapidly. As the optimal temperature for a given type of cel) is approached, the increase in growth with increase in temperature becomes smaller until finally, above the optimal temperature, increases in temperature produce lower growth rates. This is because at higher temperatures competing processes become more important. In most cells these processes are related to the thermal lability of critical chemical constituents of the cell. The competition of two processes can produce a single "window". However, the existence of multiple "windows" over a range of a single variable has been reported. This case cannot be explained as simple competition between two processes and a more complex theoretical explanation is required.
Therapeutical potential of metal complexes of quinoxaline derivatives: a review
Published in Journal of Coordination Chemistry, 2022
Chrisant William Kayogolo, Maheswara Rao Vegi, Bajarang Bali Lal Srivastava, Mtabazi Geofrey Sahini
DNA cleavage activity was carried out under UV light (365 nm), laser irradiation (635 nm), and in dark conditions, with and without the reducing agent mecarptopropionic acid (MPA). All the complexes had no activity to DNA in the dark, however, in the presence of MPA, a complete cleavage from supercoiled to nicked and linear forms of DNA occurred. The nuclease activity increased with higher reduction potentials of the CuII/CuI couple, typical of a mechanism based on Cu(I) formation which had low potentials, contrary to similar copper complexes reported [62]. Such unexpectedly higher nuclease activities are explained under the increased lability of the complexes under the reductant MPA and the electrochemical nature of the formed chemical species. Under photoinduced cleavage, the complexes demonstrated high cleavage ability with 95 performing better than 94 despite both completely cleaving the supercoiled DNA to nicked circular and consequently linear form. Complex 93 displayed the highest cleavage activity in the series, completely converting the supercoiled DNA to linear form, indicating the affinity of dpq ligand to DNA. The cleavage activity of the complexes followed the same trend under laser-induced irradiation but without conversion to the linear form of DNA but with a different relative activity (with 93 having the same activity as 94). The complexes became active when the laser irradiation was done at 3 mW and a 12 W lamp [62]. These results suggest that such complexes have the potential to be developed and used for photodynamic therapy (PDT).
Precipitation mechanism of soluble phosphates in mortar
Published in European Journal of Environmental and Civil Engineering, 2019
Maria Criado, D. M. Bastidas, V. M. La Iglesia, A. La Iglesia, J. M. Bastidas
The mortar samples show similar behaviour for both studied water:cement ratios (0.5 and 0.6). Considering the lability of the ion, the low penetration capacity of the phosphate solutions and the possibility of interaction between phosphate and portlandite in the mortar, it can be concluded that the use of the sodium monofluorophosphate (MFP), DHP and trisodium phosphate (TSP) as corrosion inhibitors presents some limitations in the case of total or partial immersion. The formation of canaphite (Na2CaP2O7⋅4H2O) by reaction between MFP and calcium hydroxide hinders the penetration process of MFP in the cement mortar. As evidenced in the present work, MFP presents a higher penetration profile compared to the DHP or TSP compounds. The stability of the phosphate ions vs. pH was calculated using thermodynamic data to obtain the following stability ranges: pH 2–4 for ion, pH 5−9 for ion, pH 3–6 for ion, pH 8–12 for ion, and pH above 11 for ion.
Copper(II) and cobalt(II) complexes of 5-methyl pyrazole-3-carboxylic acid: synthesis, X-ray crystallography, thermal analysis and in vitro antimicrobial activity
Published in Journal of Coordination Chemistry, 2018
Ananyakumari Santra, Paula Brandao, Harekrishna Jana, Gopinath Mondal, Pradip Bera, Abhimanyu Jana, Pulakesh Bera
Complexes of copper(II) and cobalt(II) with 5-methylpyrazole-3-carboxylic acid (Hmpca) are synthesized and characterized by X-ray crystallography, TGA, DFT and cyclic voltammetry study. Both monomeric and polymeric copper(II) complexes are obtained from the influence of different counter ions in the reaction mixture. Monomeric 1 adopts a square pyramidal structure where pyrazolyl N and O (carboxylate) of ligand occupy the corners of the square plane, and the axial position is occupied by a water molecule. The polymeric structure of 2 is obtained where the square planes are attached with other square planes through an axial O (carboxylate). Cobalt(II) complex (3) has distortion in its structure due to Jahn–Teller effect which holds two water molecules weakly. The loosely bound water molecules are labile with respect to ligand substitution. The lability of the present complexes favors formation of ROS for the cell destruction of microbes under investigation. Moreover, the present complexes have high lipophilicity showing better permeation to the cell wall leading to cell death. These combining effects of lability and lipophilicity need to be explored to search for new drugs.