Enzyme unit many kinds of substance besides enzymes (for example, vitamins and hormones). Enzyme unit The enzyme unit (symbol U or sometimes EU) is a unit for the amount of a particular enzyme. One U is defined as the amount of the enzyme that produces a certain amount of enzymatic activity, that is, the amount that catalyzes the conversion of 1 micro-mole of substrate per minute. The conditions also have to be specified: one usually takes a temperature of 25°C and the pH value and substrate concentration that yield the maximal substrate conversion rate. The enzyme unit was adopted by the International
Entropy entropy, have dimensions of energy divided by temperature, which has a unit of joules per kelvin (J K) in the International System of Units (or kg m s K in terms of base units). The entropy of a substance is usually given as an intensive property—either entropy per unit mass (SI unit: J K kg) or entropy per unit amount of substance (SI unit: J K mol). The French mathematician Lazare Carnot proposed in his 1803 paper "Fundamental Principles of Equilibrium and Movement" that in any machine the accelerations and shocks of the moving parts represent losses of "moment of