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
Ground substance smaller amount of ground substance compared to the fibrous material. The meaning of the term has evolved over time. Ground substance Ground substance is an amorphous gel-like substance in the extracellular space that contains all components of the extracellular matrix (ECM) except for fibrous materials such as collagen and elastin. Ground substance is active in the development, movement, and proliferation of tissues, as well as their metabolism. Additionally, cells use it for support, water storage, binding, and a medium for intercellular exchange (especially between blood cells and other types of cells). Ground substance provides lubrication for collagen fibers. The components