1. Enzymes, Coenzymes, and Vitamins Review
Chapter 18
Enzymes, Coenzymes, and Vitamins
Review

2. Enzymes Catalysts for biological reactions Usually proteins
Do not affect the equilibrium constant of a reaction.
Lower the activation energy of a reaction.
Usually proteins
Examples:
Catalase (catalyzes decomposition of H2O2)
Papain (catalyzes protein hydrolysis)

3. Enzyme Cofactors
Non-protein parts of enzymes that are essential for the catalytic activity of the enzyme.
Metal ions
Coenzymes
Organic molecules (derived from vitamins) that act as enzyme cofactors

4. Vitamins Water-soluble vitamins Thiamine (vitamin B1)
Deficiency causes beriberi (fatigue, poor appetite, weight loss, nerve degeneration, heart failure).
Thiamine diphosphate (TPP) is a coenzyme in some decarboxylase enzymes.
Dietary sources include liver, yeast, whole grains.

5. Vitamins Water-soluble vitamins Riboflavin (vitamin B2)
Needed for good vision, healthy skin and hair.
Flavin adenine dinucleotide (FAD) is a coenzyme in oxido-reductases.
Dietary sources include liver, eggs, green vegetables, whole grains.

6. Vitamins Water-soluble vitamins Niacin (vitamin B3)
Deficiency causes pellagra (dermatitis, muscle fatigue, mouth sores, mental disorders).
Coenzymes include nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+).
Dietary sources include brewer’s yeast, meat, whole grains.

7. Vitamins Water-soluble vitamins Pantothenic acid (vitamin B5)
Deficiency results in fatigue, retarded growth, anemia.
A component of coenzyme A
Dietary sources include brewer’s yeast, meat, eggs, whole grains.

8. Vitamins Water-soluble vitamins Pyridoxine (vitamin B6)
Deficiency results in fatigue, dermatitis, anemia, retarded growth.
Converted to the coenzyme pyridoxal phosphate (PLP).
Dietary sources include meat, nuts, whole grains, spinach.

9. Vitamins Water-soluble vitamins Cyanocobalamine (vitamin B12)
Deficiency causes pernicious anemia, neurodegeneration.
A coenzyme in methyltransferases.
Dietary sources include meats, fish.

10. Vitamins Water-soluble vitamins Ascorbic acid (vitamin C)
Deficiency causes scurvy (bleeding gums, bruising), neurodegeneration.
Dietary sources include fruits and vegetables.

11. Vitamins Water-soluble vitamins Biotin (vitamin H)
Deficiency causes dermatitis, anorexia, depression.
Dietary sources include yeast, liver, nuts, eggs.

12. Vitamins Water-soluble vitamins Folic acid (vitamin M)
Deficiency causes dermatitis, anorexia, depression.
Dietary sources include yeast, liver, green vegetables.

13. Vitamins Fat-soluble vitamins Retinol (vitamin A)
Deficiency causes night blindness, dry skin.
Dietary sources include yellow and green fruits and vegetables.

14. Vitamins Fat-soluble vitamins Cholecalciferol (vitamin D3)
Deficiency causes rickets, osteomalacia.
Dietary sources include cod liver oil, eggs, enriched dairy products.

15. Vitamins Fat-soluble vitamins Tocopherol (vitamin E)
Deficiency causes hemolysis of red blood cells, anemia.
Dietary sources include meat, whole grains, vegetables, vegetable oils.

16. Vitamins Fat-soluble vitamins Phylloquinone (vitamin K)
Deficiency causes hemorrhage, delayed blood clotting.
Dietary sources include liver, spinach, broccoli.

17. Vitamins