1 / 12

What you should know from today’s lecture

What you should know from today’s lecture. Examples and chemical basis of the diversity of proteins and their functions. Levels of protein structure and the chemical bonds that stabilize each level. 3-D structure determines biological function. Denaturation. Enzymes and catalysis.

step
Télécharger la présentation

What you should know from today’s lecture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What you should know from today’s lecture • Examples and chemical basis of the diversity of proteins and their functions. • Levels of protein structure and the chemical bonds that stabilize each level. • 3-D structure determines biological function. • Denaturation. • Enzymes and catalysis. • Enzyme cofactors, vitamins, and minerals. • Biochemical pathways.

  2. The diverse functions of proteins

  3. Levels of protein structure Fig. 3.16, p. 43

  4. Would you like to: • Reduce human suffering? • Win a Nobel Prize? • Become richer than Bill Gates? • Here’s how:

  5. Why is it so hard to predict protein folding? • Even a small protein made of just 100 amino acids has 3200 possible backbone configurations. • The fastest supercomputers can do 1015 calculations per second. • Even at that speed, it would take 1080 seconds to calculate the 3-dimensional shape of the small protein. • The universe is only 1020 seconds old. • A real protein folds in a microsecond (10-6 seconds).

  6. Protein denaturation • Hydrogen bonds are broken, destroying 3-D structure, and, therefore, protein function • Denatured proteins are less soluble in water • Covalent peptide bonds are NOT broken • Common protein denaturants are gentle heat (100oC or less), solvents such as ethanol, even violent mechanical action such as beating an egg white • Sometimes reversible, sometimes not

  7. Biochemical reactions A-P-P-P ATP A-P-P + P + energy ADP substrates (reactants) products • Rules of thumb: • Chemical reactions proceed spontaneously from few complex molecules to a greater number of less complex molecules; from higher bond energy to lower energy • Making a more complex molecule from simpler substrates requires energy input

  8. Catalysts • Increase the rate of a chemical reaction • Do not affect the equilibrium of the reaction • Participate in the reaction but are not ‘used up’ • Are neither a substrate nor a product of the reaction • Protein catalysts (enzymes) are exquisitely specific for their substrates and products • Enzymes typically accelerate reaction rates by thousands or millions of times

  9. The effect of enzymes on chemical reactions G1P : G6P OH O P 1:19 O O HO HO HO O P HO OH OH OH

  10. How do enzymes work? Sucrase Glucose + Fructose Sucrose Lock-and-key Induced fit

  11. Enzyme cofactors (coenzymes) • Provide a wider range of chemically active ‘functional’ groups than are available in the 20 amino acid ‘R’ groups • Vitamins Example: nicotinic acid (niacin) in NADH and NADPH • Minerals Iron (Fe++) in hemoglobin Magnesium (Mg++) in chlorophyll

  12. Biochemical pathways

More Related