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
Cartan formalism (physics) the normal Einstein–Hilbert action, using the relations formula_95 and formula_96. Note that in terms of the Planck mass, we set formula_97, whereas the last term keeps all the SI unit factors. Note that in the presence of spinor fields, the Palatini action implies that formula_98 is nonzero. So there's a non-zero torsion, i.e. that formula_99. See Einstein–Cartan theory. Cartan formalism (physics) The vierbein or tetrad theory much used in theoretical physics is a special case of the application of Cartan connection in four-dimensional manifolds. It applies to metrics of any signature. (See metric tensor.) This section is an approach to