Enzymes

Have you ever wondered who discovered enzymes?
Well, enzymes were actually discovered accidently by a scientist known as Eduard Buchner in 1897 (that was just a little known fact that the video failed to mention).
Ok, now you may be thinking how was it discovered?
Like any other discovery it was by accident. Buchner was interested in how yeast could convert sugar to alcohol but more specifically he had the idea that yeast may contain proteins. Basically he proved that fermentation actually occurred by what is known to be enzymes.
This video explains with a suitable example the function of enzymes…
What are enzymes?
Enzymes are proteins but they can also be RNA molecules. A familiar function of enzymes are as catalyst which serves to speed up a reaction, without enzymes chemical reactions would be too slow which would not make life possible.
Enzymes as catalyst:
Enzymes are specific and only work for a specific reaction, for example proteinase which hydrolyzes peptide bonds. So, an enzyme-catalyzed reaction occurs when an the enzyme binds to the substrate to form a complex. The enzyme has an area known as the active site where the substrate binds. After this occurs the enzyme may undergo minute changes to accommodate the substrate this is described as the
induced fit. As this occurs it lowers the activation energy, i.e. the minimum energy required to allow the reaction to proceed.
The affects of temperature, pH on the enzyme…
In chemicals reactions as the temperature increases, the rate of the reaction also increases. However, this is not the case with enzymes, instead as the temperature increases the denaturation of the enzyme occurs. Therefore the optimal temperature for the enzymes to work in the human body is 37°C.
pH is the measure of the H+ concentration. The pH meter ranges from 1 to 14 that is acidic-neutral- alkaline. Enzymes work in the optimum pH of 6 to 8. However, pepsin is the exception, since it needs a pH of 2 which is in gastric juice. Changes in the pH affect the complex particularly when the substrate binds to the enzyme as well as the rate of the breakdown of the complex. Note that buffers in the system adjust the change in pH.

Glycolysis Made Easy

YouTube Video 2- Glycolysis

This video on glycolysis is very concise and appealing to the eyes. The video makes use of a step by step diagram which is easy to follow. The notes are short and to the point. According to the video glucose is converted to glucose-6-phosphate by adding a phosphate group from ATP in the presence of hexokinase. Glucose-6-phosphate is converted to fructose-6-phosphate by phospoglucose isomerase which is then converted to fructose-1,6-bisphosphate by adding a phosphate group from ATP in the presence of phosphofructokinase. The fructose-1,6-bisphosphate is converted to 2 triose phosphate isomers, dihydroxyacetone Phosphate and glyceraldehyde-3-phosphate, by the enzyme aldose. The enzyme triose phosphate isomerase regulates these isomers by favouring one over the other depending on the concentration of ATP and ADP. When the body requires ATP glceraldehyde-3-phosphate is favoured and is converted to two 1,3-bisphosphoglycerate by the removal of H+ and addition of a phosphate group from NAD+P in the presence of glyceraldehyde phosphate dehydrogenase. 2 ATP is produced by removing a phosphate group in the presence of phosphoglycerate kinase to produce two 3-phosphoglycerate. These are converted to 2-phosphoglycerate by phosphoglyceromutase. Enolase is used to remove 2 water molecules to produce two phosphoenolpyruvate. Finally pyruvate kinase converts the phosphoenolpyruvate to 2 pyruvate by removing a phosphate group per compound to produce 2 ATP. Therefore in total 4 ATP is produced per glucose, 2 ATP is used per glucose, 2 pyruvates is produced per glucose, 2 NADH+H is produced per glucose and 2 water molecules is produced per glucose.