Vmax & the Michaelis-Menten Constant Substrate concentration affects the rate of catalysis in an enzyme-substrate reaction When the substrate concentration is fixed (and enzyme concentration is...
Rate: Inhibitor Concentration There are two types of inhibitors: Competitive inhibitors have a similar shape to that of the substrate molecules and therefore compete with the substrate for the acti...
Rate: Enzyme Concentration Enzyme concentration affects the rate of reaction The higher the enzyme concentration in a reaction mixture, the greater the number of active sites available and the grea...
Rate: pH All enzymes have an optimum pH or a pH at which they operate best Enzymes are denatured at extremes of pH Hydrogen and ionic bonds hold the tertiary structure of the protein (ie. the enzym...
Rate: Temperature Enzymes have a specific optimum temperature – the temperature at which they catalyse a reaction at the maximum rate Lower temperatures either prevent reactions from proceeding or ...
Colorimetry to Measure Enzyme Activity A colorimeter is able to measure light absorbance (how much light is absorbed) or light transmission (how much light passes through) a substance Colorimetry c...
Measuring Enzyme Activity The progress of enzyme-catalysed reactions can be investigated by: Measuring the rate of formation of a product using catalase Measuring the rate of disappearance of a sub...
How Enzymes Work The lock-and-key hypothesis Enzymes are globular proteins This means their shape (as well as the shape of the active site of an enzyme) is determined by the complex tertiary struct...
Mode of Enzyme Action Enzymes have an active site where specific substrates bind forming an enzyme-substrate complex The active site of an enzyme has a specific shape to fit a specific substrate Ex...
