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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Ribonucleotide or ribotide is a nucleotide containing D-ribose as its pentose component. It is considered a molecular precursor of nucleic acids. Nucleotides are the basic building blocks of DNA and RNA. The monomer itself from ribonucleotides forms the basic building blocks for RNA. However, the reduction of ribonucleotide, by enzyme ribonucleotide reductase (RNR), forms deoxyribonucleotide, which is the essential building block for DNA. There are several differences between DNA deoxyribonucleotides and RNA ribonucleotides. Successive nucleotides are linked together via phosphodiester bonds.
Small Interfering RNAs, MicroRNAs, and NPs in Gynecological Cancers
Published in Loutfy H. Madkour, Nanoparticle-Based Drug Delivery in Cancer Treatment, 2022
An example of this system is CALAA-01, which is a targeted nanocomplex that includes an anti-R2 siRNA [114]. This targeted therapeutic system has been designed to inhibit tumor growth. The selected siRNA prevents the tumor from growing via RNAi to decrease expression of the M2 subunit of R2 (ribonucleotide reductase). This system was used in clinical studies in patients bearing solid tumors [115].
One-pot construction of gemcitabine loaded zeolitic imidazole framework for the treatment of lung cancer and its apoptosis induction
Published in Journal of Experimental Nanoscience, 2023
Zhan Li, Tiantian Du, Wen Yang, Shenni Yi, Na Zhang
Difluorodeoxycytidine (gemcitabine, termed GEM) is a pyrimidine antimetabolite chemically like deoxycytidine [8]. GEMs mode of action has been thoroughly studied and understood. Deoxycytidine kinase may convert GEM to dFdCMP, dFdCDP and dFdCTP or deoxycytidine deaminase can convert it to difluorodeoxyuridine [9]. The latter enters DNA and causes a break in the strand. Incorporating dFdCTP into DNA is less efficient than cytosine arabinoside (ara-C), so DNA exonuclease is more challenging to remove [10–12]. This likely adds to more intracellular accumulation of dFdCTP than ara-C, which may, in part, account for its distinct spectrum of preclinical and clinical action [13]. The enzyme ribonucleotide reductase, which generates the deoxynucleotides necessary for DNA synthesis, is also inhibited by GEM. Several human tumour xenografts and a wide range of mouse solid tumours and leukaemias respond to GEM treatment [14].
Synthesis, crystal structures and anti-cancer mechanism of Cu(II) complex derived from 2-acetylpyrazine thiosemicarbazone
Published in Journal of Coordination Chemistry, 2022
Yunyun Zheng, Bin Li, Yu Ai, Mengyao Chen, Xinhua Zheng, Jinxu Qi
In the 1840s, thiosemicarbazides were found to exhibit significant biological activity; however, their mechanism of action has not been fully understood [28–30]. Thiosemicarbazone and its Cu(II) complex have a wide range of therapeutic uses as potential anti-tuberculosis drugs [31]. A series of thiosemicarbazide analogues are used in clinical studies, such as Thioacetazone, Methisazone, 5-HP, 3-AP, Triapine, COTI-2 and DpC [32], with Triapine being the most representative analogue [33–35]. Initial studies have shown that thiosemicarbazone inhibits the activity of ribonucleotide reductase, thereby inhibiting DNA synthesis and exerting its anti-cancer effect [29]. Further studies have shown that the anti-cancer activity of thiosemicarbazone is the result of a combination of various mechanisms [16]. These ligands are good metal chelators, and the complexes formed by coordinating with metals have redox activity [36–39]. The catalysis of hydrogen peroxide to produce reactive oxygen species (ROS) in living organisms is extremely important [40–42].
A three-dimensional manganese(II) coordination polymer: synthesis, structure and catecholase activity
Published in Journal of Coordination Chemistry, 2020
Prama Bhattacherjee, Partha Mitra, Prasenjit Sarkar, Rohith P. John
Manganese is a metal which can readily shuttle between oxidation states +2 and +3. This behavior is widely utilized in redox metalloenzymes, such as catalase, ribonucleotide reductase, superoxide dismutase and dioxygenase [1]. Manganese enzymes have various types of active sites having different nuclearity, including the tetranuclear manganese clusters that exist at the reactive site of photosynthetic water oxidation [2]. This has led researchers to develop manganese complexes of different nuclearity not only to develop better and efficient catalysts, but also in the design of single-molecule magnets [3]. Several multinuclear manganese complexes with diverse structures such as rings [4], clusters and coordination polymers have been studied, owing to their structural diversity [5], magnetism [6], sensing [7] and catalysis [8]. The choice of manganese in many such synthetic models is due to the fact that it is a redox-active metal ion, has flexible coordination geometry and therefore offers plenty of choice for structural modulation [9–11]. Dinuclear manganese complexes are widely utilized for various catalytic conversions, such as epoxidation, hydroxylation, and hydrosilylation/hydrogermylation [12–15]. Polynuclear manganese complexes also show interesting magnetic anisotropy properties [16]. In addition, various multinuclear manganese complexes are also shown to catalyze conversions such as oxygen transfer reactions and water oxidation [17, 18].