How Enzymes Work Goals: Define enzymes as proteins which functions as biological catalysts. Explain enzyme action in terms of the "lock and key hypothesis" Investigate and describe the effect of temperature and of pH on enzyme activity - Enzyme LAB.

Speed in chemical reactions can be very important Speed in chemical reactions can be very important. Think of what would happen if the food you just ate took three days to digest. Enzymes – biological catalysts (or substances) that can change the speed of chemical reactions without themselves being changed..

Properties of Catalysts: Only a small amounts are needed Change the speed of reactions Remain unchanged after reaction. Are "reusable” Are Proteins Are Highly specific (each only work on certain substances) Usually end with “ase or sometimes with “in”

Examples: Maltase – works on maltose Lipase – works on lipids Enzymes are specific Every reaction in a cell requires a specific enzyme. Enzymes are named for their substrates: substance that an enzyme acts on. Maltase – works on maltose Lipase – works on lipids Proteases – work on proteins

Lock and Key Model of How Enzymes Work Copy below diagram into notes:

Another Look Enzymatic Hydrolysis or Dehydration Synthesis? What is missing?

Coenzymes Coenzyme Some enzymes need Coenzymes to function properly. Vitamins often function as Co-enzymes ex. niacin Coenzyme

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter6/animations.html

Enzymatic Dehydration Synthesis A + B + H2O --enzyme C products substrate

Enzymatic Hydrolysis C --enzyme A + B + H2O substrate products

Enzymatic Hydrolysis Animation

Factors that Affect Enzyme Action Temperature pH

Enzymes and Temperature. Low temperatures - enzymes are inactive. As temperature increases enzymes activity increases (therefore reactions will get faster). Each enzyme has an optimum temperature at which they work best. - often 37 C When the temperature is too high, the enzymes are destroyed, or denatured.

Enzymes and Temperature. Substrate concentration constant Low temperatures - enzymes are inactive. As temperature h enzymes activity h (reactions speed up). Each enzyme has an optimum temperature. When temperature gets too high, enzymes are destroyed, or denatured. (see animations next two pages).

Enzyme Denatured Heat

Enzyme Denatured Active site is deformed and no longer functions

Review of pH pH scale determines how acidic or basic a substance is. pH of 7 is neutral 1-6 is acidic 7-14 is basic.

Substrate concentration constant Enzymes and pH. Substrate concentration constant Each enzymes work best at optimum pH. If the pH is very high or very low, enzymes can be denatured.

Rate of an enzymatic reaction as a function of temperature and pH

Enzyme Review See Mr. Wanamaker’s site http://www.lpscience.fatcow.com/jwanamaker/animations.htm