Enzymes

• Enzymes are proteins that act as catalysts in biochemical reactions.
• Convention This is the transfer of heat through direct contact between particles of matter. In solids, this is primarily how heat is transferred. Heat energy is passed from one particle to the next as they collide with each other. Materials that are good conductors, like metals, allow heat to flow easily, while insulators, like wood or air, impede the flow of heat.
• Temperature - Most enzymatic reactions occur optimally within a narrow range of temperatures. If the temperature is too low, the enzyme will not function properly; if it is too high, the enzyme may denature.
• The rate at which an enzyme-catalyzed reaction occurs depends on several factors:
• pH - The pH level at which an enzyme functions best is called its optimum pH. Many enzymes have an optimal pH near neutrality (7).
• Substrate Concentration - As substrate concentration increases, reaction rate also increases up to a certain point. Beyond this point, increasing substrate concentrations no longer increase reaction rates because all active sites on the enzyme molecules are already occupied by substrates.
• Inhibitors can be reversible or irreversible inhibitors. Reversible inhibition occurs when the inhibitor binds to the enzyme but does not cause permanent damage. Irreversible inhibition occurs when the inhibitor causes permanent damage to the enzyme.
• pH - The pH of the environment can affect the shape of the active site of an enzyme, making it more or less effective at binding substrates. For example, some enzymes work best in acidic environments (low pH), while others prefer basic conditions (high pH).
• Active Site - A specific region on the surface of an enzyme where the substrate binds.
• Lock and Key Model - An old model of enzyme action that suggests that the shape of the active site matches exactly with the shape of the substrate.
• Induced Fit Model - Proposed by Daniel Koshland in 1956, this model suggests that when a substrate enters the active site of an enzyme, the enzyme changes slightly to better fit the substrate. This change allows the enzyme to more effectively lower the activation energy required for the chemical reaction to proceed.
• Competitive inhibitors compete with the normal substrate for binding to the active site of the enzyme. They do not change the shape of the active site, so the enzyme can still catalyze the reaction once the competitive inhibitor has been removed.
• Noncompetitive inhibitors bind to another part of the enzyme than the active site. They alter the structure of the active site, making it impossible for the substrate to bind. Once the noncompetitive inhibitor has been removed, the enzyme cannot return to its original form.
• Enzymes are biological catalysts that speed up chemical reactions without being consumed themselves. They lower the activation energy required for a reaction to take place.
• Characteristics of living things
• Living organisms have cells