sacofactor coenzyme

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 Catalysis by Coenzymes Some common coenzymes • One carbon metabolism – Biotin – Tetrahydrofolate Transfers CO 2 One carbon groups C O H to CH 3 Catalysis by Coenzymes Some common coenzymes • Acyl groups and others – Coenzyme A – Lipoic acid – Thiamine pyrophosphate – Pyridoxal phosphate – 5’-Deoxyadenosyl- cobalamin Transfers Acyl groups Acyl groups Aldehydes Amino groups and amines Alkyl groups Vitamin Derived Coenzymes folate Folate Varies Coenzyme Derived from Deficiency causes NAD Niacin Pellagra FAD Riboflavin (B 2 ) Dermatitis Biocytin Biotin Seborrhea (skin) Tetrahydro- Vitamin Derived Coenzymes Thiamin (B 1 ) Βεριβερι Πψροδοξαλ πηοσπηατε Πψριδοξινε (Β 6 ) ς αριεσ 5 −∆εοξψαδεν− οσψλχοβαλαµ ιν ς ιταµιν Β 12 Περνιχιουσ Ανεµια Coenzyme A Pantothenate + others Fatigue Irritability Thiamine pyrophosphate Examples of Coenzyme Catalysis Uncatalyzed reaction CO 2 H CR NH 3 H H CR NH 3 H R C H NH 3 C O O R C H NH 3 C O O R C H NH 3 C O O Examples of Coenzyme Catalysis Catalysis with pyridoxal phosphate (Vitamin B 6 derivative) Schiff Base R C H NH 3 C O O N H X X X X CH O + H 2 O N H X X X X HC R C H NH C O O Examples of Coenzyme Catalysis CO 2 N H X X X X HC R C H NH C O O N H X X X X HC R C H NH C O O N H X X X X HC R C H NH C O O N H X X X X HC R C H NH N H X X X X HC R C H NH