1. Action of Enzymes
Enzymes are proteins.
NO EFFECT on ΔH, ΔS, ΔG.
Increases the rate of the reaction by decreasing Ea
Action of enzyme is determined by tertiary and quaternary structure.
Substrate – the “reactant” molecule in the catalyzed reaction.
Active Site – the specific site on the enzyme molecule that catalyzes the reaction.
Each enzyme catalyzes a specific chemical reaction.

3. Enzymes – induced fit

4. Enzymes – induced fit

5. Factors that affect the rate of a catalyzed reaction
Cofactor – A substance that attaches to an enzyme in order to increase its effectiveness.
Coenzyme – an organic cofactor.
Factors that affect the rate of a catalyzed reaction
[enzyme] – first order Rate = k[E]
As concentration of enzyme increases, more substrate molecules can be catalyzed

6. [Substrate]
As concentration increases, rate increases (first order kinetics) up to a point – enzyme saturation. When all enzyme molecules are working at capacity, rate levels off.

7. Km = Michaelis-Menten constant
Vmax Km
Vmax = The maximum rate of a reaction for a particular enzyme concentration.
Km = Michaelis-Menten constant
Represents approximate [substrate] in human body under normal conditions
Equal to [substrate] at ½ Vmax

8. Inhibitor – A substance that attaches to enzyme and slows down (inhibits) the action of the enzyme
Irreversible inhibition – occurs if the inhibitor bonds covalently to the enzyme
Reversible if weak forces are present (H-bonds, dipole-dipole, LDF)
Competitive Inhibition – The inhibitor attaches at the active site, preventing the substrate from binding with the enzyme. (example is CO or CN-)
To reduce the effect, we can increase the substrate concentration

9. Non-competitive inhibition – Inhibitor binds to the enzyme at a site other than the active site. This causes the shape of the active site to change, so that the enzyme will no longer fit into the active site properly. (heavy metal ions)

10. Temperature
Most efficient at body temperature. As temperature increases or decreases, tertiary structure changes, altering active site.

11. pH
Each enzyme has an optimal pH. The further you get from that pH, the less effective it is (denaturation occurs)

12. Uses of Enzymes in Biotechnology Fermentation – production of alcohol
Wine – yeasts in grape skin turn sugars into alcohol
2 (C6H10O5)n + n H2O n C12H22O11
C12H22O11 + H2O 2 C6H12O6
C6H12O C2H5OH + 2 CO2
Cheese manufacture – fermentation of lactose.
Penicillin – fermentation to make antibiotic.
Enzyme immobilization
Genetic Engineering (anti-virals)

13. Carbohydrates Carbohydrates have empirical formula Cx(H2O)y.
Carbohydrate means hydrate of carbon.
Most abundant carbohydrate is glucose, C6H12O6.
Carbohydrates are polyhydroxy aldehydes and ketones.
Glucose is a 6 carbon aldehyde sugar and fructose is a 6 carbon ketone sugar.
The alcohol side of glucose can react with the aldehyde side to form a six-membered ring.

14. Most glucose molecules are in the ring form.
Note the six-membered rings are not planar.
Focus on carbon atoms 1 and 5: if the OH groups are on opposite sides of the ring, then we have -glucose; if they are on the same side of the ring, then we have -glucose.
The - and - forms of glucose form very different compounds.

18. Disaccharides
Glucose and fructose are monosaccharides.
Monosaccharides: simple sugars that cannot be broken down by hydrolysis with aqueous acids.
Disaccharides are sugars formed by the condensation of two monosaccharides. Examples: sucrose (table sugar) and lactose (milk sugar).
Sucrose is formed by the condensation of -glucose and fructose.
Glycoside linkage – “ether” bond formed when monosaccharides combine to form disaccharides or polysaccharides (C-O-C).

19. Lactose is formed from galactose and -glucose.
Sucrose is about six times sweeter than lactose, a little sweeter than glucose and about half as sweet as fructose.
Disaccharides can be converted into monosaccharides by treatment with acid in aqueous solution.

20. Polysaccharides
Polysaccharides are formed by condensation of several monosaccharide units.
There are several different types. Example: starches can be derived from corn, potatoes, wheat or rice.

21. Starch performs storage of glucose in plants and animals.
Starch contains 1,4 and 1,6 linkages.
Enzymes catalyze the conversion of starch to glucose.
Starch is poly -glucose whereas cellulose is poly -glucose.
Enzymes that hydrolyze starch do not hydrolyze cellulose because of the different shapes of the polymers.
Ingested cellulose is recovered unmetabolized. This is referred to as dietary fiber.

22. Polysaccharides
Cellulases are enzymes that enable animals to use cellulose for food and break down cellulose by hydrolysis. These enzymes are absent in most animals, including mammals.

24. Major Functions of Carbohydrates
Energy sources
Energy reserves (glycogen)
Structure (cellulose)
Dietary Fiber – mainly plant material that is not digested by hydrolyzed by enzymes in the human digestive tract.
Importance – may help prevent diverticulitis, IBS, constipation, obesity, Crohn’s disease, hemorrhoids, and diabetes mellitus.

25. Respiration
The process by which glucose is converted to energy.
Aerobic – C6H12O6 + 6 O2  6 CO2 + 6 H2O
First, glucose reacts with O2 to produce pyruvic acid, C3H4O3:
C6H12O6 + O2  2 C3H4O3 + 2 H2O

26. Then, pyruvic acid is oxidized to form CO2 and H2O:
2 C3H4O3 + 5 O2  6 CO2 + 4 H2O
Hemoglobin, with Fe2+ attached, carries O2 from the lungs to the cells, then carries CO2 from the cells to the lungs.
Cytochromes, with Fe3+ or Cu2+ attached, facilitate the oxidation of glucose (metal ion is reduced to Fe2+ or Cu+)
Anaerobic – C6H12O6  2 CO2 + 2 C2H5OH
(fermentation)

27. Anaerobic – In humans, pyruvic acid is converted to lactic acid:
Otherwise, pyruvic acid becomes ethanol:
C6H12O6  2 CO2 + 2 C2H5OH
(fermentation)