Biological enzymes

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Biological enzymes

Most biological enzymes are 3D globular proteins and perform chemical reactions in cells. An example is haemoglobin, which is needed for the vital carrying on oxygen in blood around to the body from the lungs to the organs that need it. Enzymes serve as Essential Catalysts to virtually every bodily process. An enzyme shortage can cause a variety of illnesses e.g. blue baby syndrome and sickle cell amoeba.

Not all proteins are enzymes, but most enzymes are proteins (the exception is catalytic RNA). A catalyst is a molecule, which increases the rate of a reaction but is not the substrate of that reaction and does not get used up in the reaction. A substrate is a molecule upon which an enzyme acts to yield a product. Enzymes convert a substrate molecule into a different molecule.

Many of the reactions in catabolism are favourable. This means that these reactions will occur spontaneously even outside of a living organism. But one major problem is, they are too slow to be of any use in a biological system. If cells did not have ways of speeding up catabolism, life would be impossible. In all biological reactions Enzymes accelerate the rate of the reaction.

There are enzymes that do specific functions, thus work one certain substrate, such as digestive enzymes are used to break down food molecules and help with digestion, e.g. the breaking down of protein molecules to amino acids.

Enzymes also work in specific conditions, such as the right concentration, pH and temperature. Most enzymes denature at 45 C and hence work at an optimum temperature.

All Enzymes are made inside the cell; intracellular, by the process of protein synthesis. But some enzymes are secreted from the cell and act upon substrates in the extracellular fluids, this type of enzyme is referred to as a exoenzyme. Other enzymes act upon substrates within the cytoplasm or organelles of the cell this type of enzyme is referred to as an endoenzyme. Constitution enzymes are made by the cell at a constant rate regardless of the level of the substrates for that enzyme. Inducible enzymes are produced in response to the exposure of the cell to the substrates for that enzyme. The Lac operon is an example of a mechanism that allows for enzyme induction.
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Also most enzymes have hydrophilic side chains attached to them but some are very hydrophobic. Enzymes are proteins, which themselves are polymers of amino acids. Some enzymes have extra molecules associated with them, besides amino acids, which assist in the reaction they carry out.

Enzymes prefer to break down substrates that are in a transition state. They get the substrate into the right conformation, and then they breakdown the substrate into products.

The part of the enzyme that does the work is called the active site (active cleft). The residues in this site are in ...

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