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Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
The name of an enzyme has two parts. The first part is the name of the substrate, and the second part is terminated with a suffix -ase (54). For example, protease is an enzyme of the substrate protein. For the international nomenclature, the name of an enzyme is preceded by the two letters EC (Enzyme Commission) followed by four numbers. For example, E.C.2.7.1.1. The first number denotes one of the six main classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. The second number denotes the subclass and the third number denotes the sub-subclass. The last number denotes the serial number of the enzyme in its sub-subclass (53–54). Enzymes are classified based on the reactions they catalyze into six classes cited above. Oxidoreductases such as glutathione reductase, lactate dehydrogenase, and glucose-6-phosphate dehydrogenase are the enzymes that catalyze oxidation-reduction reactions of their substrates. Transferases transfer a functional group between two substrates such as a methyl or phosphate group. Hydrolases catalyze the hydrolysis reactions of carbohydrates, proteins, and esters. Lyases cleave various chemical bonds by other means than hydrolysis and oxidation for the formation of double bonds. Isomerases are involved in isomerization of substrate where interconversion of cis-trans isomers is implicated. Ligases such as alanyl-t-RNA synthetase, glutamine synthetase, and DNA ligases join together two substrates with associated hydrolysis of a nucleoside triphosphate (53–54).
Chemopreventive Agents
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
On the other hand, Phase II enzymic transformations, also known as conjugation reactions, facilitate the attachment of small polar molecules (e.g., sugars) to xenobiotics or intermediate Phase I metabolites to produce less biologically active and/or or more water-soluble molecules that can be eliminated more easily. A wide variety of enzymes participate in this process, including glutathione-S-transferases (GSTs), sulfotransferases, UDP-glucuronosyltransferases (UGT), N-acetyltransferases (NATs), and methyltransferases (MTs). Some chemopreventive agents may work by enhancing the Phase II metabolism of pro-carcinogens or carcinogens thus facilitating their elimination from the body.
Overview of the Biotransformation of Antiepileptic Drugs
Published in Carl L. Faingold, Gerhard H. Fromm, Drugs for Control of Epilepsy:, 2019
Introduction. Conjugation of a drug with an endogenous molecule generally utilizes transferases, enzymes which transport the endogenous substance from a high energy intermediate to the drug molecule. There are specific transferases for each type of conjugation. Two phase II reactions are of primary importance in anticonvulsant drug biotransformation — glucuronidation and interactions with glutathione.
Methamphetamine leads to the alterations of microRNA profiles in the nucleus accumbens of rats
Published in Pharmaceutical Biology, 2020
Jing Yang, Lihua Li, Shijun Hong, Dongxian Zhang, Yiqing Zhou
A total of 40 differentially transcribed miRNAs (p value < 0.01 & |log2 (fold change)| > 1 in comparison with the control group (Figure 3(A)), 17 up-regulated and 23 down-regulated by METH treatment, were found with quantitative information and included in the next bioinformatic analyses (Figure 3(B)). Differential miRNAs were verified using qPCR, and their relative abundance was consistent with the results of the sequencing analysis (Figure 4). The potential targets of the changed miRNAs were annotated according to their biological process, cellular component, and molecular function by BLAST2TO (Figure 5(A)). Biological processes analysis showed that these proteins were mainly involved in cellular component regulation, localization regulation, regulation of transport, intracellular signal transduction, and organic substance transport. We observed that most of the targets of the differential miRNAs were located in the intracellular region and organelles in the cellular component analysis. Molecular function analysis revealed that a large proportion of the targets played a role in protein binding, enzyme binding, kinase binding, and transferase activity.
Profile of adult patients admitted with drug-induced liver injury at a district hospital in Pietermaritzburg, KwaZulu-Natal
Published in South African Family Practice, 2019
Current literature describes the link between anti-TB treatment and DILI. Direct toxicity has been found with isoniazid (INH) and pyrazinamide (PZA). The major drug-metabolising enzyme of INH is N-acetyltransferase2 (NAT2).19,20 Other possible enzymes include CYP2E1 and glutathione S-transferase. Abnormalities in the genes that encode for these enzymes (especially for NAT2) may predispose to problems in enzyme metabolism of drugs. NAT2 has been extensively studied and has shown that slow acetylator phenotype will increase risk of DILI when patients are exposed to INH, and some sulphonamides.13,14,19,20 Huang showed that NAT2 slow acetylators (CYP2E1 c1/c1 genotype) were at significantly higher risk of isoniazid hepatotoxicity than rapid acetylators (CYP2E1 c1/c2 or c2/c2 genotypes; OR, 7.43).19 In developing countries where finances are scarce, this form of DILI identification might prove difficult.
Difference and alteration in pharmacokinetic and metabolic characteristics of low-solubility natural medicines
Published in Drug Metabolism Reviews, 2018
Shenglei Yan, Yuying Liu, Jianfang Feng, Hua Zhao, Zhongshu Yu, Jing Zhao, Yao Li, Jingqing Zhang
Natural medicines, including low-solubility natural medicines, have attracted wide attention in recent years. For the first time, the metabolism and pharmacokinetic behavior of low-solubility natural medicines, the factors influencing them, and their delivery systems are systematically reviewed (Figure 1). These drugs are metabolized to more active, less active or inactive metabolites, and even to toxic compounds by oxidases, reductases, hydrolases, and transferases. Investigating metabolites with higher bioactivity may lead to the discovery of new drugs, and toxic side effects may be prevented by analyzing toxic metabolites. Most low-solubility natural medicines are mainly metabolized in the liver by cytochrome P450s (especially CYP3A and CYP2C) in phase I reactions and by UGT in phase II reactions. Stereo configuration has a large influence on metabolism. Pharmacokinetic properties, such as bioavailability and half-life may be favorably changed by choosing suitable formulation, administrative route, dosage, animal species, and drug–drug interactions. This review is useful for physicians and pharmacists to guide more accurate treatment with low-solubility natural medicines by increasing drug efficacies and protecting patients from toxic side effects.