China
Africa
Explore chapters and articles related to this topic
Methods of Protein Iodination
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
The compound, 1,3,4,6-tetrachloro-3a,6a-diphenylglycoluril (mol wt 431.91), is expected to be practically insoluble in aqueous media because of the two phenyl-substituted carbons of the glycoluril skeleton (Figure 15, Structure 2). It is marketed by Pierce Chemical Co., Rodeford, 111., under the trademark, Iodo-gen®. Its insolubility in water prompted Fraker and Speck,41 in 1978, to propose its use as an iodinating agent; since lodo-gen® is immobilized on the wall of the reaction vessel, direct exposure of the protein to the oxidant is minimized. Correspondingly, the danger of oxidative scissile side reactions would be reduced by comparison to a chloro-compound that is freely water soluble.
Melanotropin Mechanisms of Action: Melanogenesis
Published in Mac E. Hadley, The Melanotropic Peptides, 2018
John Pawelek, John McLane, Michael Osber
Freychet et al.31 reported the synthesis of 125I-labeled insulin in 1971. This achievement upened the way for studies on receptors for insulin and led to the development of techniques for iodination and isolation of many biologically active peptide hormones. Varga et al.10 first reported the synthesis of 125I-labeled β-MSH and the use of this ligand to investigate MSH receptors in cultured melanoma cells. Lambert and Lemer,11 Lambert et al.,32 and Lambert and Varga33 later described an improved synthesis and purification of 125I-β-MSH which resulted in the isolation of a radioactive ligand that was monoiodinated at a single tyrosine residue and that retained full biological activity when compared to nonradioactive (β-MSH. Their methods employed the use of IodoGen® (l,3,4,6-tetrachloro-3,6-diphenyl-glycoluril, Pierce Chemicals, Inc.) as a catalyst during the iodination reaction and isolation of the 125I-β-MSH by reversed phase high-performance liquid chromatography (HPLC). Recently, the number of studies on receptors for MSH has increased markedly as has a concomitant need for a supply of 125I-MSH. Improvements on the original techniques have now led to methodology wherein millicurie amounts of 125I-MSH can be isolated and stored for at least 6 weeks. The following outlines our current procedures for synthesis and storage of this important ligand.
Dendrimers as Drug and Gene Delivery Systems
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
PPI dendrimers were also chemically modified for improved physiological properties. Park and coworkers investigated ternary complex of PPI dendrimer linked with DABs to its periphery (PPI–DAB), DNA, and cucurbituril (CB) for a non-covalent strategy in developing a gene delivery carrier.85 CB is a large-cage compound composed of glycoluril units interconnected with methylene bridges, and it is able to form stable pseudorotaxanes with strings derived from DAB moeities of PPI–DAB through multiple non-covalent interactions.86,87 The DNA binding capacities of PPI, PPI–DAB, and PPI–DAB/CB decreased with increasing generation and increased in the order, PPI > PPI–DAB ≥ PPI–DAB/CB. Fluorescence experiment using DAB-tethered acridine indicated that there was no change in the CB beads threaded on PPI–DAB after the addition of DNA to the PPI–DAB/CB binary complex. Importantly, in vitro transfection results showed that CB had no negative influence on the transfection efficiency of polymer/DNA binary complex, and the ternary complex was a highly active form of gene delivery vector, suggesting that this promising system can be applied to other non-covalent molecular recognitions, and it would be possible to create a really functional gene delivery carrier if the functionalized-CB were synthesized. Recently, another approach to developing gene delivery carriers with PPI dendrimers involved methyl quaternary ammonium derivatives of PPI dendrimers with varying generation.88 Quaternization of DAB-cored PPI dendrimer (DAB 8) with eight surface amines (Q 8) proved to be critical in enhancing DNA binding and resulted in improved colloidal stability and vector tolerability on i.v. injection of the polyplex.
Novel strategies for the fight of Alzheimer’s disease targeting amyloid-β protein
Published in Journal of Drug Targeting, 2022
Yang Xie, Yan Wang, Shangfei Jiang, Xiaohong Xiang, Jianhua Wang, Linhong Ning
In addition, another metal complex (ruthenium) was accepted as a potential anti-AD agent, which was developed as alternatives to platinum complex [64,65]. Studies focussed on a number of ruthenium complexes-based drugs targeting Aβ were carried out for seeking AD therapeutic drug candidates [66,67]. In particular, Jones and co-workers investigated the anti-amyloid activities of ruthenium complex KP1019 (Figure 4), which is also a widely studied anti-cancer agent [68]. The result showed that KP1019 did prevent in vitro human nerve cell from Aβ-induced neurotoxicity via inhibiting the formation of Aβ aggregates and dissembling preformed Aβ aggregates, which was enabled by binding to histidine residues of Aβ. Recently, Storr’s research group reported a series of ruthenium complexes derived from NAMI-A with the imidazole ligand substituted for pyridine derivatives, also showed potential in modulating the aggregation of Aβ [69]. Besides, Kumbhar and co-workers investigated a range of ruthenium polypyridyl complexes with enhanced inhibitory effect against Aβ aggregation by tetra-xylene bipyridine glycoluril [67]. Furthermore, metal complexes (such as iridium and cobalt) also showed binding affinity with Aβ and exhibited inhibition potential for AD therapy [70,71].