enzyme cofactors การใช้

• Some 4Fe 4S clusters bind substrates and are thus classified as enzyme cofactors.
• Apolipoproteins also serve as enzyme cofactors, receptor ligands, and lipid transfer carriers that regulate the metabolism of lipoproteins and their uptake in tissues.
• Metal cofactors are bound tightly to specific sites in proteins; although enzyme cofactors can be modified during catalysis, they always return to their original state by the end of the reaction catalyzed.
• The coupling of photochromic units to enzymes or enzyme cofactors even provides the ability to reversibly turn enzymes " on " and " off ", by altering their shape or orientation in such a way that their functions are either " working " or " broken ".
• Structurally, it is a dinucleotide that only differs from the house-keeping enzyme cofactor, NADP by a hydroxyl group ( replacing the nicotinamide amino group ) and yet this minor modification converts it into the most potent Ca 2 +-mobilizing second messenger yet described.
• The three diseases are classified together as the GM2 gangliosidoses, because each disease represents a distinct molecular point of failure in the activation of the same enzyme, beta-hexosaminidase . "'AB variant "'is caused by a failure in the gene that makes an enzyme cofactor for beta-hexosaminidase, called the GM2 activator.
• Other organisms require additional metals as enzyme cofactors, such as vanadium in the nitrogenase of the nitrogen-fixing bacteria of the genus " Azotobacter ", tungsten in the aldehyde ferredoxin oxidoreductase of the thermophilic archaean " Pyrococcus furiosus ", and even cadmium in the carbonic anhydrase from the marine diatom " Thalassiosira weissflogii ".
• Although a sodium-dependent transporter for vitamin C exists, it is present mainly in specialized cells, whereas the glucose transporters, the most notable being GLUT1, transport Vitamin C ( in its oxidized form, DHA ) in most cells, where recycling back to ascorbate generates the necessary enzyme cofactor and intracellular antioxidant, ( see Transport to mitochondria ).