Canadian Medical Guide > Chemicals and Drugs > Enzymes and Coenzymes > Enzymes > Ligases Terms and Definitions

Ligases

	Carbon-Carbon Ligases - Enzymes that catalyze the joining of two molecules by the formation of a carbon-carbon bond. These are the carboxylating enzymes and are mostly biotinyl-proteins. EC 6.4.
	Carbon-Nitrogen Ligases - Enzymes that catalyze the joining of two molecules by the formation of a carbon-nitrogen bond. EC 6.3.
	Carbon-Oxygen Ligases - Enzymes that catalyze the joining of two molecules by the formation of a carbon-oxygen bond. EC 6.1.
	Carbon-Sulfur Ligases - Enzymes that catalyze the joining of two molecules by the formation of a carbon-sulfur bond. EC 6.2.
	Polynucleotide Ligases - Catalyze the joining of preformed ribonucleotides or deoxyribonucleotides in phosphodiester linkage during genetic processes. EC 6.5.1.
	Ubiquitin-Protein Ligase Complexes - Complexes of enzymes that catalyze the covalent attachment of UBIQUITIN to other proteins by forming a peptide bond between the C-terminal GLYCINE of UBIQUITIN and the alpha-amino groups of LYSINE residues in the protein. The complexes play an important role in mediating the selective-degradation of short-lived and abnormal proteins. The complex of enzymes can be broken down into three components that involve activation of ubiquitin (UBIQUITIN-ACTIVATING ENZYMES), conjugation of ubiquitin to the ligase complex (UBIQUITIN-CONJUGATING ENZYMES), and ligation of ubiquitin to the substrate protein (UBIQUITIN-PROTEIN LIGASES).

Ligases Medical Definitions and Terms