Enzyme :: essays research papers

The plot of enzyme activity Vs. pH is often " gong shaped" since two different amino acid groups of the enzyme are existence titrated to different states of ionization at the different pH value. This means that that one of the two possible ionization states of the amino acid place chain is effective in enzyme catalysis - in other words, if an acerbic side chain like Glu is involved in catalysis, it probably totally works when it is ionized since Glu side chain carboxylic acid groups make water a pK around pH 5, at pH determine on a lower floor this pK, the enzyme will be less active voice while at pH values above the pK, the enzyme will be most active. At high pH values, another group, for example, the amino side chain group in a Lys may control the activity. So at pH values below the pK of the Lys amino side chain, which is about pH 9, the enzyme is active, while at pH values above the Lys side chain pK, the enzyme will be less active. In the end, the pH optimum li es somewhere between the pK values for these two groups that control the enzymes activity.B. Temperature OptimumMost enzymes allow an optimum temperature, which may be related to the type of organism from which the enzyme was isolated. Some organisms like plants bring forth well tightly fitting room temperature and so their enzymes are most active at a temperature around 30 to 40C. A ordinary rule of thumb from chemistry is that a reactions rate approximately duplicate with a 10C increase in reaction or assay temperature. However, since enzyme are held together by weak non-covalent bonds, at high temperatures, the enzyme catalyzed rate slows down rather than increases Of courese, at low temperatures, all the molecules in the solution slow down and so does the enzyme catalyzed reaction. At high temperatures, the caloric movement of the molecules become to great for the enzyme to hold its shape or bod and so it begins to denature and lose its activity. Animal enzymes often hav e temperature optima near 37C (especially humans since this is body temperature). For thermophilic organisms, like bacteria or blue-green algae which grow well in near boiling acerbic springs, much higher temperature optima are found some enzymes even have temperature optima near 90C.In the end, the temperature you use for an enzyme assay may see on the equipment available to you in the lab.