Cofactors and Coenzymes - Biochemistry and ….ppt

Cofactors and Coenzymes Cofactors Groups or molecules (other than amino acid residues) which are important to catalysis Metals Coenzymes If tightly bound, it is called a prosthetic group Enzyme without prosthetic group (cofactor) Apoenzyme Enzyme with prosthetic group (cofactor) Holoenzyme Catalysis by Coenzymes Some common coenzymes Transfers Oxidation/Reduction Nicotinamide Adenine Dinucleotide (NAD+) Flavin Adenine Dinucleotide (FAD) Hydride ion (H-) Electrons Vitamin Derived Coenzymes Vitamin Derived Coenzymes Examples of Coenzyme Catalysis Uncatalyzed reaction Examples of Coenzyme Catalysis Catalysis with pyridoxal phosphate (Vitamin B6 derivative) Examples of Coenzyme Catalysis Examples of Coenzyme Catalysis Examples of Coenzyme Catalysis Nicotinamide adenine dinucleotide and alcohol dehydrogenase Examples of Coenzyme Catalysis The amine is released from the coenzyme following more electron shifts. Electron shifts occur and carbon dioxide is lost. The amino acid adds to pyridoxal phosphate to form a Schiff base which is a key intermediate in many transformations. Decarboxylation of an amino acid in an uncatalyzed reaction. Symptoms of vitamin deficiencies. Symptoms of vitamin deficiencies Coenzymes involved in group transfers. Single carbon functional coenzymes. Redox coenzymes. Definitions illustrated. Title slide - this section. Cofactors ( an atom or molecule essential for the action of a large molecule, cofactors may include metals or coenzyme) and coenzymes - an organic substances that enhances or is necessary for the action of enzymes. NAD+ reactive site, the yellow R is an H in NAD+ and a phosphate in NADP+ FAD reactive sites Oxidation of an alcohol to a ketone or aldelhyde FAD oxidation of a hydrocarbon chain - this kind of reaction occurs in fatty acid oxidation The oxidized and reduced forms of FAD Complete reduction of a keto to a CH2 CoA (coenzyme A) is an acyl carrier. The Ac~CoA bond is high energy. The reactive site on CoA is the -SH * Catal