What are Enzymes

Enzymes are biocatalysts which are produced by living cells and are highly proteinaceous in nature. Enzymes are renowned for their effectiveness as they virtually influence all biological processes in our living system. Biological processes such as respiration, digestion, responsible for synthesizing and analyzing carbohydrates, fats, proteins and amino acids. Enzymes are also involved in harvesting energy released by cells. Enzymes are responsible for the occurrence of all metabolic reactions at the cellular level in our body. Every cell produces hundred types of enzymes but these enzymes work outside the cell and not inside. Each enzyme works on a single substance or group of substance.

Some facts about enzymes

  • Enzymes are formally protein
  • Every catalytic activity is in someway associated with their protein structure.

  • Enzymes are active catalyst and forms a linking negotiator between the substrates or substance.

  • While accelerating any cellular reaction enzymes do not change their chemical composition.

Historical perspective

In 1878, Kuhne coined the term enzyme while he was working with some biocatalysts which were known as ferments at that time. The word, enzyme comes from another term, “in yeast”, as it was accidentally discovered while scientists were performing experiments on fermentation caused by yeast extracts.

It was Edward Buchner who accidentally discovered enzyme. When Buchner was working on a yeast extract he found some activity which made it worse. He tired around three to four times but the change was so rapid that the yeast always turned bad than his expectation. He added glucose to decelerate the process but surprising he got alcohol as a result of sugar fermentation. Pasteur had already discovered the phenomenon and named it living cell fermentation. However, Buchner added clarity to Pasteur discovery, as he confirmed that yeast extract can only bring about fermentation. In 1903, Buchner made the breakthrough as he was able to isolate enzyme. He received the Nobel Prize for this discovery.

Lock and Key model

The mechanism of enzyme activity is termed as lock and key. 1894, Emil Fischer wrote his hypothesis on enzyme activity and explained it with an example of lock and key. The enzyme is the key and the substrate is the lock. If a perfect match is found then the enzyme binds with the substrate and opens the lock. He said that every enzyme has an active site which joins with the substrate forming an enzyme+subtable complex. This is an irreversible process as the complex can split if a perfect match is not found, similar to lock and keys. Factors such as size, charge and shape of the active site of enzyme and substrate play an important role in binding.

After forming complex subtable enzyme easily separates the product from the substrate by using the amino acids in it and thus catalyzes the reaction. Hence, the above theory was named lock and key.

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