Enzyme Activity z Amount of reaction that a certain amount of enzyme will produce in a specified period of time z Activity determined by measuring the amount of product formed or substrate that disappeared z IU of enzyme activity is – The amount of enzyme necessary to produce 1 µmole of product (or the loss of 1 µmol of substrate) per minute under specified conditions of substrate concentration, pH and TemperatureEnzyme Activity z Amount of reaction that a certain amount of enzyme will produce in a specified period of time z Activity determined by measuring the amount of product formed or substrate that disappeared z IU of enzyme activity is – The amount of enzyme necessary to produce 1 µmole of product (or the loss of 1 µmol of substrate) per minute under specified conditions of substrate concentration, pH and Temperature