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Radionuclide-based Diagnosis and Therapy of Prostate Cancer
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Sven-Erik Strand, Mohamed Altai, Joanna Strand, David Ulmert
Macrocyclic chelators – for example, DOTA, NOTA, DOTAGA, NODAGA, and CB-TE2A – impose the highest degree of preorganization. They exhibit high thermodynamic stability like acyclic chelators but excel in being kinetically inert. Due to their high kinetic inertness, less radiometal decorporation occurs in vivo and, consequently, less accumulation of the radionuclide in normal non-targeted tissues is observed [54]. In order to increase the reaction kinetics, higher temperatures (higher than that required by CHX-A”-DTPA) and longer reaction times are required to obtain efficient labelling yields. These conditions might not be compatible with heat-sensitive targeting agents like antibodies [56].
Laccase-Mediated Synthesis of Novel Antibiotics and Amino Acid Derivatives
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Surprisingly, no amination was observed for the substrate 3-(3,4-dihydroxyphenyl)-propionic acid (66) which was reported to react readily with 4-aminobenzoic acid to a separable heteromolecular dimer (Niedermeyer et al., 2005). Thus, an important influence of the amino coupling partner on the reaction kinetics appears very likely. However, a more detailed view of the characteristics of the nucleophiles acting as donors in the ongoing Michael addition reactions during the amination of the quinoid intermediate suggests a further possible reason for the poor reactivity of 3-(3,4-dihydroxyphenyl)-propionic acid (66) and also 3,4-dihydroxybenzoic acid (64) and 3,4-dihydroxyphenylacetic acid (65) towards the amino-ß-lactams.
Methods of Protein Iodination
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
Whether using H2O2 or galactose oxidase/glucose, iodination by lactoperoxidase, in most workers' hands, is a reaction lasting for several minutes (usually 5 to 20 min). The work published from Malmo,69,84,85 showing >80% efficiencies achieved in 1 sec, remains a notable exception in this regard. The A412/A280 ratio of the enzyme and the protein/enzyme ratio in the reaction mixture84 used by these authors compare well with the values published by others. Nevertheless, this speed is unexpected from the reaction kinetics measured by Marchalonis68 and Graf et al.86 The likely solution is that the reactivity with iodine differs greatly among proteins,68 and the hormones under consideration (insulin, glucagon) probably label extremely easily in a comparative sense. This certainly holds true for insulin.87
Optimization and kinetic modeling of interchain disulfide bond reoxidation of monoclonal antibodies in bioprocesses
Published in mAbs, 2020
Peifeng Tang, Zhijun Tan, Vivekh Ehamparanathan, Tingwei Ren, Laurel Hoffman, Cheng Du, Yuanli Song, Li Tao, Angela Lewandowski, Sanchayita Ghose, Zheng Jian Li, Shijie Liu
Different types of fragments may exist in the mAb solution. Based on the primary CE-SDS NR analysis, the major contents in the initial solution are light chain (L), heavy chain (H), heavy-heavy fragment (HH), half-mer (HL), heavy-heavy-light fragment (HHL) and intact (H2L2 or Mono). The simplified reaction pathways can be illustrated as scheme 1and the reaction kinetics can be expressed as
Synergistic response of physicochemical reaction parameters on biogenesis of silver nanoparticles and their action against colon cancer and leishmanial cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Bilal Javed, Zia-ur-Rehman Mashwani, Abdullah Sarwer, Naveed Iqbal Raja, Akhtar Nadhman
Followed by increasing the concentration of AgNO3 to 3 mM to understand the effects of varying pH conditions on the synthesis of SNPs (Figure 3). The highest synthesis of SNPs was recorded in acidic (pH 5) conditions (Figure 3(A)) and there was no marked synthesis on neutral and basic pH (Figure 3(B,C)). The next phase of the study includes the increase of AgNO3 concentration up to 5 mM and there was synthesis similar to 3 mM at acidic pH (Figure 3(D)). The asymmetrical peaks were observed to represent the meagre synthesis of SNPs at basic and neutral pH (Figure 3(E,F)). The above experiments showed 3 mM of AgNO3, and maintenance of the acidic pH as the optimum conditions for the synthesis of SNPs by using M. longifolia leaves aqueous extract. The pH of the reaction mixture provides a steering force to increase or decrease the concentration of H+ ions which directly alters the electronegative state of reactants. At lower pH the concentration of the H+ ions increases and vice versa. Increasing the concentration of H+ ions in the reaction mixture subsequently increases the collision or interaction of the reactants and directly influences the reaction kinetics. The pH does not directly influence the structural conformation of enzymes and proteins. However, the change in the concentration of H+ ions in the reaction mixture can shape and alter the morphological properties of the substrate by changing the electronegative states that can affect their binding with the enzymatic active site [1].
Single pot synthesized gold nanoparticles using Hippophae rhamnoides leaf and berry extract showed shape-dependent differential nanobiotechnological applications
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Catalytic degradation of dyes is a thermodynamically favourable process but the large potential difference between donor (BH4-) and acceptor (dyes) acts as kinetic barrier and decreases the feasibility of reaction. The catalytic activity of AuNPs along with a reducing agent NaBH4, overcomes the kinetic barrier by acting as electron donor, ultimately leading to dye degradation [28]. Thus, no reduction of dyes was observed even after a week, in the absence of nanocatalysts (Figure 7). Reaction kinetics confirmed a linear correlation between ln(Ct/C0) versus reaction time (min) and a pseudo-first-order kinetics. Higher rate constants (14–67%) for BE nanotriangles in comparison with LE nanospheres reaffirmed their better nanocatalytic efficacy. Well defined edges/corners of BE nanotriangles bounded by <110> facets exhibit more catalytic sites, which enhance their affinity towards reactant molecules, due to accelerated electron transfer process [29] (Figure 8).