1 / 12

Enzymes

Enzymes. SBI 4U September 14 th , 2012. What are Enzymes?. Enzymes are …. Enzymes are proteins (tertiary or quarternary ) that catalyze (i.e., increase the rates of) chemical reactions. What is a Catalyst?.

gotzon
Download Presentation

Enzymes

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. Enzymes SBI 4U September 14th, 2012

  2. What are Enzymes?

  3. Enzymes are … Enzymes are proteins (tertiary or quarternary) that catalyze (i.e., increase the rates of) chemical reactions

  4. What is a Catalyst? • A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change • In catalyzed reactions, the reactants are converted into products faster than they would be without the catalyst

  5. All reactions require Activation Energy • Activation Energy is defined as the energy that must be overcome in order for a chemical reaction to occur • Heat provides activation energy for most reactions

  6. Temperature is key! • Even though an increase in temperature is needed for most reactions to occur, too much heat can denature proteins, causing them to lose their function! • Therefore, catalysts allow reactions to proceed at suitable rates at moderate temperature by reducing the activation energy needed to catalyze reactions

  7. What does an enzyme act on? • An enzyme acts on a substrate • A susbtrate is the reactant that an enzyme acts on when it catalyzes a chemical reaction • The substrate binds to a particular site on the enzyme to which it is attracted

  8. Enzymes are very specific as to which substrate they bind to – they usually don’t bind to isomers of their substrate • The names of enzymes usually end in –ase. For example: amylase (found in saliva), lactase (found in small intestine)

  9. The Process of an Enzyme-Catalyzed Reaction • Substrate binds to the enzyme at the active site (located on the enzyme) • Substrate’s functional groups functional groups come close to the functional groups of a number of amino acids as the substrate approaches the active site. This allows the protein to change its shape, thereby better accommodating the structure – induced-fit model • The attachment of the enzyme’s active site creates the enzyme-substrate complex

  10. How do Temperature and pH affect Enzyme Activity? • Temperature – if temperature increases beyond the critical point, the protein structure can be disrupted and the enzyme can lose its function • Thus, every enzyme has an optimal temperature at which it works best • Ex: most human enzymes work best at normal body temperature 37 C, while those archaebacteria work best at above 100 C • Ph – Like temperature, enzymes work best at an optimal pH. Ex: Pepsin works best in an acidic environment with a Ph of 2

  11. Cofactors & Coenzymes • Cofactors “helper molecules” – non-protein compounds that are bound to a protein and required for the protein’s biological activity. Cofactors are usually enzymes themselves. Example: vitamins & minerals • Cofactors include zinc and manganese ions • Coenzymes – derivatives of vitamins. Also help with catalysis

More Related