Enzymes; poisons and drugs
A drug is either a substance which is used within diagnostics, treatment or prevention of a disease or illness; however drugs are also used on a recreational level and will cause changes within the central nervous system. A poison is a substance that caused injury, illness or death especially by chemical means.
Many drugs and poisons are enzyme inhibitors; they bind to an enzyme and decrease their activity. The way in which an inhibitor may work is by attaching to the enzymes active site and therefore blocking any enzyme substrate complexes from forming. Many drugs are enzyme inhibitors due to them being able to block the activity of an enzyme, therefore being able to kill a pathogen or to correct a metabolic imbalance.
Then there are competitive and non-competitive inhibitors. A competitive inhibitor will have a shape which is very similar to that of the substrate molecule which means that it will be able to fit within the active site of the enzyme; this is why it is called a competitive inhibitor as it is competing with the substrate for a place within the active sites of the enzymes. When the inhibitor is fitted within the active site it will not cause any new products to be formed due to slight difference between the inhibitor and the substrate molecule. A non-competitive inhibitor is one that does not compete with the substrate for a place but instead it will attach to the enzyme molecule in a region away from the active site. This will then cause a distortion in the tertiary structure of the enzyme molecule and change the shape of the active site therefore making no substrate molecules able to fit within the active site, therefore no enzyme substrate complexes form and therefore a slower rate of reaction. The binding of an inhibitor is either reversible or irreversible. If it is an irreversible inhibitor it will usually react with the enzyme and then change it chemically, via covalently bond formations, modifying key amino residues needed for enzymatic activity. Then there are reversible inhibitors which bind non- covalently.
An example of a poison is snake venom which includes a mixture of toxins and different enzymes with many of them containing almost 90% proteins. There are two types of snake venom; neurotoxins and hemotoxins. Neurotoxins affect the central nervous systems of the victim and will usually result in interference with the heart and cause a fall in blood pressure. Then there are hemotoxic poisoning snakes in which effect their prays circulatory system and muscle tissue causing excessive scarring, gangrene, permanent disuse of motor skills and sometimes leads to the amputation of the affected area. There are roughly 20 different enzymes in which venomous snakes can have although none will have all of them. These are some example of enzymes which are included within snake venoms; * Cholinesterase; this will attack the nervous system causing muscles to relax to the point where the prey has little control. * Amino acid oxidase; plays a part in the digestion and triggering of other enzymes. * Hyaluronidase; causes other enzymes to be absorbed more rapidly by the prey. * Proteinase; plays a large part