Enzymes

• Enzymes are large biological molecules that are responsible for the thousands of metabolic processes that sustain life.

• They are:– highly selective catalysts– greatly accelerating rate of metabolic reactions– greatly decrease the energy needed for a reaction– Mostly proteins, although some catalytic RNA

molecules have been identified.

Structure• Enzymes are a 3-D

structure that are highly complex.

• Their structure is very important because they are specific to their substrates.

• Enzyme origins:– Listen, will be important

when we get to genetics.

Lock and Key Model

• Enzyme, Substrate, Product

Amylase• Foods with Maltose– Sweet potatoes– Grain Cereals– Pears– McDonald Hotcakes– Catsup [Ketchup]– Tootsies rolls

Lock and Key

Energy savers• Like all catalysts, enzymes work by lowering the activation

energy– this dramatically increasing the rate of the reaction.

• Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions.

• As with all catalysts, enzymes are not consumed by the reactions they catalyze

• However, enzymes do differ from most other catalysts in that they are highly specific for their substrates. – Enzymes are known to catalyze about 4,000 biochemical

reactions.

Lowers activation energy

Enzyme activity can be affected by:

• Other molecules– Inhibitors– Activators• Many drugs and poisons are enzyme inhibitors

– Temperature– Pressure– Chemical environment (pH)– Concentration of substrate

Pressure

• How could pressure effect enzymes?– Under pressure, dun dun dun da di dun dum!

Temperature

pH

Substrate concentration

Review

The experiment

• What’s the enzyme?

• What’s the substrate?

• What’s the product?

The experiment

• What’s the enzyme?– Catalase

• What’s the substrate?– H2O2

• What’s the product?– H20 + O2

The Experiment

• Basic Idea????

• How would you test pH’s affect on catalase?

• How would you test temperatures effect on catalase?

• How would you test for different amounts of substrate?

The Experiment

• Test for pH– Keep the concentration of yeast the same but

make a range of pH to test.• Test for temperature– Keep the concentration of yeast the same but

make a range of temperatures.• Substrate concentration– Change the concentration of the substrate.

BTW, inhibitors