Daily Newsletter February 15, 2012

Daily Newsletter February 15, 2012

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Today's Topic: Enzymes, structure and function.

•  First thing to remember, Eynzymes are Proteins!
• So they are constructed on ribosomes.
• Their structure is determined by electrostatic interactions.
• Their shape can change when things bind to it.
• They can be denatured.
• Second, they act as catalysts.
• They lower activation energy by brining molecules together in the correct alignment, and can induce molecular tension to cause the reaction.
• Though their shape may change during the chemical reaction, the enzyme is left essential unchanged at the end of the reaction.

Enzymes work by binding the substrate of the reaction, and then inducing molecular tension.  Remember, when something binds to a protein, the electrostatic interactions around the protein change, resulting in a conformational (shape) change in the protein. It is this shape change that will induce molecular tension.

Every enzyme has an active site.  This is the place where the substrate(s) will bind to the enzyme.  The active site must have a shape that loosely fits the substrate, and the electrochemical pattern of the active site must compliment the electrochemical pattern of the substrate.  When they bind, you get an Enzyme Substrate complex.  Below is a basic cartoon about the process:

Here is a quick video that shows the brief conformational change that helps to induce the reaction.


Conformational changes alone are not the only part in inducing a reaction.  You will also find that proteins can have prosthetic groups that aid them in their action.  For example, you can a Heme group with Iron that can hold Oxygen in red blood cells.  Some digestive enzymes use Chromium to help in their action.  Many metabolic pathways will contain Electron Carriers needed for redox reactions.  We will see examples of these over the next few weeks.

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Daily Challenge: There are three enzymes that we will come across next week. Today, you are to look at the action of these three enzymes and articulate how they work. Use the information above as guidance, but be specific for each of these three enzymes. One point to look at is whether or not these enzymes require additional prosthetic groups or coenyzmes/cofactors. The enzymes are glucokinase (hexokinase 4), glyceraldehyde-3-phosphate dehydrogenase, and aldolase. [Wikipedia warning: be careful with wikipedia on this one. Some enzymes have good descriptions, while others are either too technical or poorly written.]

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Admin Note: As of today, only 7% of the students have started the calibrations. Do not delay. You will only hurt yourself if you wait until the last minute.