Enzymes are catalytic molecules that speed up the rates of reactions.
(a) Explain why enzymes are necessary in biological systems.
(b) Discuss three control mechanisms that regulate enzymatic activity.
A) Enzymes decrease the amount of activation energy required for chemical reactions to occur.
B) 1. Cofactors and Coenzymes- Inorganic ions and non protein organic molecules that are necessary to be present on the active site for some enzymes to work. These cofactors participate in the reaction and may even accept or contribute atoms to the reactions.
2. Competitive and Noncompetitive inhibition- Limits the enzyme activity. This occurs when a molecule binds to an enzyme, either on the active site or allosteric site, and decreases its activity.
3. Allosteric Regulation- Causes a different shape in the enzyme. May either inhibit or stimulate an enzymes activity.
Cells regulate enzyme activity through two methods: allosteric inhibition and competitive inhibition. Allosteric inhibition is when something (an ion, an organic chemical, etc.) bonds to a site on the enzyme (not on the active site), and changes the shape of the enzyme. Competitive inhibition is when something (an ion, an organic chemical, etc.) enters the active site so that the true substrate cannot enter into the enzyme to have a reaction.
Enzymes are regulated by controlling the level of transcription for them as well as inhibition. Inhibition is when a compound or protein physically contacts the enzyme and reduces activity. It can block the active sight or bind allosterically and reduce activity. Some inhibitors are not for regulation but compounds from outside of the organism. Many poisons are inhibitors of crucial enzyme activity.
Enzyme activity can be regulated by several factors including temperature, pH, and other cell proteins.
Most cells contain proteins that help turn key enzymes "on" or "off" at critical stages in the life of the cell.
Enzyme speeds up the chemical reaction. So, it would speed the cells for life and live.
lock and key structure, only a certain substrate can bind with the uniquely shaped active site
enzymes are controlled by protein molecules that act as catalyst which speed up the reaction by lowering the activation energy.
Denature enzyme activity
Guaicol is used as a substrate for peroxidase activity, when we treat it with enzyme the activity of enzyme increases at a higher rate.
- Inhibition of an enzyme is to inhibit the catalytic activity of the enzyme. - Because, by blocking or inhibiting an enzyme's activity can kill a pathogen or correct a metabolic imbalance. Example : Inhibition of HIV protease.
Changes in pH or temperature decrease enzyme activity because bonds b reak and the enzyme returns to it's PRIMARY structure. (not tertiary)
At a high ion concentration, the ion interfere with the bonds between the side groups of the amino acids making up the enzyme (which is a protein). This causes the enzyme to lose its shape, called denaturation. If the enzyme loses its shape, it can no longer accept and react substrate, so the rate of enzyme activity decreases.
The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity
Denature enzyme activity
Physical activity can alter the shape of enzyme which can cause damage or may the enzyme become inactive
When an enzyme is frozen, it only slows down activity. Unlike boiling an enzyme, it does not stop it from working.
activators; inhibitors
Cold temperatures have a drastic effect on an enzyme's activity level. Cold temperatures usually dramatically slow down an enzyme's activity.
Enzyme activity is affected by other molecules, temperature, chemical environment (e.g., pH), and the concentration of substrate and enzyme. Activators are molecules that encourage enzyme activity, and inhibitors are enzymes that decrease enzyme activity. Sometimes a cofactor is necessary for the enzyme to work.
inhibitor
A strategy for activity-based enzyme detection using a novel enamide-based chemical strategy is described. Enzymatic cleavage of an amide.
Enzyme activity increases with temperature, but only up to a point.
Enzyme activity sometimes reflects the amount of protein expressed in a cell--however, due to enzyme inhibitors, the enzyme activity is not always reflective of the amount of protein expressed by a cell.
There are several things that determine an enzyme's activity. The main determinants include the structure of the enzyme, temperature, pH and so much more.