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Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Nucleases are enzymes that cut DNA strands by catalyzing the hydrolysis of the phosphodiester bonds. Nucleases that hydrolyze nucleotides from the ends of DNA strands are called exonucleases, whereas endonucleases cut within strands. The most frequently used nucleases in molecular biology are the restriction endonucleases, which cut DNA at specific sequences. For instance, the EcoRV enzyme recognizes the 6-base sequence 5′-GAT|ATC-3′ and makes a cut at the vertical line. In nature, these enzymes protect bacteria against phage infection by digesting the phage DNA when it enters the bacterial cell, acting as part of the restriction modification system. In technology, these sequence-specific nucleases are used in molecular cloning and DNA fingerprinting. Enzymes called DNA ligases can rejoin cut or broken DNA strands. Ligases are particularly important in lagging strand DNA replication, as they join together the short segments of DNA produced at the replication fork into a complete copy of the DNA template. They are also used in DNA repair and genetic recombination.
Genes and genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Nucleases are enzymes that cut DNA strands by catalyzing the hydrolysis of the phosphodiester bonds. Nucleases that hydrolyse nucleotides from the ends of DNA strands are called exonucleases, while endonucleases cut within strands. The most frequently used nucleases in molecular biology are the restriction endonucleases, which cut DNA at specific sequences. For instance, the EcoRV enzyme recognizes the 6-base sequence 5’-GATIATC–3’ and makes a cut at the vertical line. In nature, these enzymes protect bacteria against phage infection by digesting the phage DNA when it enters the bacterial cell, acting as part of the restriction modification system. In technology, these sequence-specific nucleases are used in molecular cloning and DNA fingerprinting. Enzymes called DNA ligases can rejoin cut or broken DNA strands. Ligases are particularly important in lagging strand DNA replication, as they join together the short segments of DNA produced at the replication fork into a complete copy of the DNA template. They are also used in DNA repair and genetic recombination.
Microbial Metabolism
Published in Maria Csuros, Csaba Csuros, Klara Ver, Microbiological Examination of Water and Wastewater, 2018
Maria Csuros, Csaba Csuros, Klara Ver
The main six classes are: Transferase—transfers functional groups such as the amino group, the acetyl group, and the phosphate group.Hydrolase—the addition of water to a substrate.Oxidoreductase—participates in oxidation-reduction reactions in which oxygen or hydrogen are gained or lost.Lyase—the removal of groups of atoms without hydrolysis.Isomerase—the rearrangement of atoms within a molecule.Ligase—joining two molecules together by using the energy usually derived from the breakdown of ATP.
Transesterification of vegetable oils into biodiesel by an immobilized lipase: a review
Published in Biofuels, 2023
Akossi Moya Joëlle Carole, Kouassi Konan Edmond, Abolle Abollé, Kouassi Esaie Kouadio Appiah, Yao Kouassi Benjamin
Enzymes are thermolabile proteins, biocatalysts in metabolic reactions. They act at low concentration and have a specificity of action. In modern biotechnology, enzymes catalyze reactions of interest to different industries, such as food, energy, medical or chemical industries. They are classified into seven main categories: oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, and translocases [46–48]: Oxidoreductases catalyze electron and proton transfers from a donor to a receptor.Example: superoxide anion and hydrogen peroxide.Transferases catalyze the transfer of groups.Example: glutathione S-transferases.Hydrolases catalyze the hydrolysis reactions of molecules.Example: lipases, esterases, proteases, amidases.Lyases catalyze decomposition reactions in which a C-C, C-O, C-N or other bond is broken without hydrolysis or oxidation.Example: fructose, bisphosphate, aldolase.Isomerases catalyze the transfer of groups in the same molecule to produce isomeric forms.Example: triose-phosphate isomerase.Ligases catalyze the joining of two molecules by new covalent bonds with concomitant hydrolysis of Adenosine-triphosphate (ATP) or other similar molecules.Example: glutamine synthetase.Translocases catalyze the movement of ions or molecules across cell membranes in general. Example: extern mitochondrial membrane.