ENZYMES & Chemical Digestion

Chemical Digestion Basics Dehydration Synthesis vs. Hydrolysis Anabolic – Dehydration Synthesis –Require the removal of water to form bonds Catabolic – Hydrolytic Reactions –Require the addition of water to break bonds Carbohydrates – mono and disaccharides Lipids (triglycerides) – glycerol + fatty acids Proteins – amino acids

enzyme substrate products enzyme Terminology: Enzyme Active site Substrate(s) Product(s) Reversible reactions

Factoids: Enzymes are: Proteins

Factoids: Enzymes: Lower the activation energy needed for a reaction to take place A B Molecule C +

Factoids: Enzymes: Are unchanged after catalyzing a reaction

Factoids: Enzymes: Turnover numbers are very high Examples: –1 molecule of acetylcholinesterase -> 25,000 molecules of acetylcholine in 1 second –1 molecule of catalase breaks down 40 million molecules of hydrogen peroxide in 1 second

Factoids: Enzymes: Are specific in their activity Lock and key model

Factoids: Enzymes: Sometimes require a nonprotein factor = cofactor (metallic ion) or coenzyme (vitamin) –Examples: Iron, zinc, copper, sodium, potassium, vitamin B

Factoids: Enzymes: are usually named after the substrate on which they act have names ending in –ase ( with a few exceptions) Examples: Cellulase Sucrase Lipase Lactase Acetylcholinesterase

Factors Affecting Enzyme Activity

Temperature

pH Pepsin – stomach enzyme Trypsin – duodenum enzyme more H+

Concentration of Enzyme or Substrate

Inhibitors Competitive Inhibition Noncompetitive Inhibition

Enzyme Uses

Papaya and Papain

Pineapple and Bromelain

Lactose = milk sugar Lactase – enzyme produced by cells that line the small intestine Symptoms Solutions –Avoid dairy products (calcium problem) and prepared foods containing lactose –Determine problematic amounts of lactose or source (i.e. milk, ice cream, aged cheeses) –Lactase additives: add to milk (lactose content reduced by 70% or buy lactose-reduced milk

Enzyme Dietary Supplements

Questions Concerning Dietary Enzyme Supplements Are there people who do not produce enough of certain enzymes? Could an increase in digestive enzymes increase the digestion of food? Can you increase the amount of digestive enzymes by taking oral dietary supplements?