Proteins Wrap Up

1. Proteins Wrap Up

2. How enzymes work • Reduce activation energy needed to start reaction • Do not change net amount of energy produced by a reaction • Exergonic release energy

3. Enzyme VS no Enzyme

4. Denaturing Enzymes • Disrupt bonds forming shape of enzyme • Denaturing can be permanent or temporary • Thermal breaks distant bonds holding tertiary structure first • pH changes charges which allows new attractions to form new shapes (interferes with H bonding)

5. pH

6. pH Urine – 6 Stomach acid – 1 Duodenum – 6 Jejunum & ileum - 7 Saliva – 6.5 Blood – 7.4

7. pH scale • 0-14 • 7 neutral • Below 7 acid • Above 7 base/alkaline • Log scale – pH 1 is 100X more acidic than pH 3

8. Optimum pH digestive enzymes Lipase (pancreas) 8.0 Pepsin 1.5 - 1.6 Trypsin 7.8 - 8.7 Urease 7.0 Amylase (pancreas) 6.7 - 7.0 Catalase 7.0

9. Optimal pH • Enzyme activity is greatest at optimal pH • Above and below optimal pH enzyme activity drops off • pH extremes can permanently denature enzymes

10. Temperature • Temperature is measure of kinetic energy • The greater the temp the faster the molecules move and the more often they collide • Lower temp = slower reaction rates • Increasing temperature increases reaction rate because of increased collisions and increased chance of interactions

11. Temperature flip side • Increasing temperature can lead to denaturing of enzymes which serves to decrease reaction rate • Higher temp – greater vibration – more likely to break bond within enzyme and denature it

12. Graph optimal temperature Interaction between denaturing of enzyme at higher temps and increasing collisions at higher temps

13. Effect of varying Concentrations • Substrate – molecule being acted on by enzyme • Enzyme – protein catalyst

14. Effect Enzyme Concentration Linear increase of activity IF substrate is unlimited

15. Effect Substrate Concentration Set amount enzyme: Rate plateaus (although never max out) because more and more enzyme active sites are being used and unavailable for other substrate molecules. More substrate than enzyme molecules available to handle them.

16. Lactose Revisited • Lactose broken into glucose and galactose • Lactase is the enzyme • Lactose intolerant people no longer produce enzyme to break down lactose – need it as baby to break down milk • Yeast produce lactase and are the source for large scale production of lactose free products

17. Advantages of lactose free products because of glucose and galactose sugars • Lactose less soluble • Lactose less sweet • When fermenting yoghurt and cottage cheese bacteria breakdown the monosaccharides faster than the lactose disaccharide • Lactose crystallizes more