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ENZYMES

Enzymes are what type of biological molecule?

What is their monomer?

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Objective:

  • Students will be able to identify the different structures of proteins and their functions.
  • Students will be able identify the limits of enzymes.

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Fireflies

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  • ENZYMES are biological catalysts.
  • Catalyst - a substance that speeds up chemical reactions in cells.

- HOW? They lower the activation energy (activation energy- amount of energy required for a reaction to occur)

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  • Speeds up reaction 10 million X.

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Activation energy

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Turn to your neighbor and complete these sentences

When a reaction occurs

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(With an enzyme or without an enzyme)

The Activation Energy is

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(more or less)

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How do they work?

  • The reactants are known as substrates (what is being broken or built)

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  • Enzymes provide a site(space) where substrates can be brought together to react. (like a docking station)

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  • This binding region on the enzyme is called the active site.

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How do they work?

  • When substrates are brought together at the active site the form a short-lived enzyme –substrate complex.

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  • Once the reaction has occurred, and the product is formed, the enzyme is released from the complex and restored to its original state.

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  • The enzyme can work again and again.

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IF YOU’RE A “HOW” PERSON

(you do not need to know this!)

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1. The enzyme may hold the substrates in such a way as to distort the substrate bonds closer to their form in the transition state. This reduces the amount of energy needed to complete the transition.

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2. The enzyme may create a charge distribution opposite to that of the transition state. This lowers the energy of the transition state and decreases the activation energy.

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3. The enzyme may reduce the reaction entropy ΔS‡ by bringing substrates together in the correct orientation to react.

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4. The enzyme may provide a completely different chemical pathway for the reaction. It may form new bonds in the ES complex that would be difficult to form without the enzyme

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The enzyme goes back to starting state and works again and again

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Remember… its actually like this

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How do Enzymes and Substrates Fit?

  • One substrate fit into active site of only one enzyme
  • Lock and Key theory

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Urokinase

Hyaluronidase

DNA topoisomerase-II

Endonucleases

Cyclo-oxygenase

Acetyl cholinesterase

Monoamine oxidase

Oxidases

Hydrolases

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DNA dependent RNA polymerase

Reductases

Lyases

Ligases

Isomerases

Glucuronidase

Transaminases

Glycogen synthase

Aminoacyl tRNA synthetase

Lactate dehydrogenase

Use your power of observation… What do all these Enzymes have in common?

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Enzyme Specificity

  • Enzymes are picky!

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  • Each enzyme catalyzes only one reaction.

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  • For example, there is a specific enzyme that breaks maltose down into 2 glucose molecules.

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  • B/C this is the only reaction this enzyme carries out- called maltase

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  • Many enzymes are named this way replacing suffix with –ase.

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Enzymes in the Human Body

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Name that Enzyme!!!

  • The enzyme that breaks down maltose is maltase
  • Using this model name the following:

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Bind DNA polymers= _

Breaks down Cellulose= _

Produces telomeres= _

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Regulation of Enzymes

  • Can be affected by:
  • pH - needs to be stable.
    • Usually neutral but there are exceptions
    • Pepsin, digestive enzyme pH 2
    • Enzymes are active over narrow range of pH.
  • temperature - enzymes in the human body work best at 37 C - normal body temperature.
  • Concentration of substrates and enzymes
  • Inhibitors
    • Competitive and non-completive

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Temperature

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pH

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CONCENTRATION

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  • Concentration- how much of a substance is present
    • Substrate Concentration- if there is more of a substance/material then the enzyme can work as fast as possible with the available resources
      • Listen for example!

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Saturation Point

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Substrate Concentration

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CONCENTRATION

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  • Concentration- how much of a substance is present
    • Enzyme Concentration- if there are more enzymes the reaction with occur faster as long as there is enough material
      • Listen for example!

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Enzyme Concentration

  • NOT EXACTLY CORRECT!!Listen for why!

This is where you’d run out of substrate

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INHIBITORS

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INHIBITORS

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  • Inhibitors- a molecule that attaches to the enzyme, not allowing the substrate to attach
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Competitive Inhibitors

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    • Competitive inhibitor-mimic substrate and physically block active site

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Noncompetitive Inhibitors

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    • Noncompetitive inhibitor-attaches to an enzyme’s allosteric (somewhere other than active site) site, but changes active site so substrate is unable to fit into active site

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Enzymes are important in:

  • 1. Regulating chemical pathways.
  • 2. Making materials that the cell needs.
  • 3. Releasing energy.
  • 4. Transferring information.