Tissue, pathway, proteinase, peptidase, protease ,acrosin, lipoprotein, activator, caspase, trypsin, papain, esterase inhibitors are proteins or receptor ligands or receptor antagonists that bind to an enzyme receptor and decreases its activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. Not all receptor antagonist that bind to enzymes are inhibitors; enzyme activator ligands or agonists bind to enzymes and increase their enzymatic activity, while enzyme substrates bind and are converted to products in the normal catalytic cycle of the enzyme.A microtiter plate (spelled Microtiter is a registered trade name in the United States) or microplate or micro well plate or multiwell, is a flat plate with multiple "wells" used as small test tubes. The microplate has become a standard tool in analytical research and clinical diagnostic testing laboratories. A very common usage is in the enzyme-linked immunosorbent assay (ELISA), the basis of most modern medical diagnostic testing in humans and animals. A microplate typically has 6, 24, 96, 384 or 1536 sample wells arranged in a 23 rectangular matrix. Some microplates have even been manufactured with 3456 or 9600 wells, and an "array tape" product has been developed that provides a continuous strip of microplates embossed on a flexible plastic tape.