electrophoresis Analytical method in which an electric field is applied to a medium (paper, thin-layer plates, polyacrylamide or agarose gel), causing charged molecules to move through it. In capillary electrophoresis, samples move through a buffer-filled tube (capillary). In gel electrophoresis, samples move through a thin agarose or polyacrylamide gel. Bigger biomolecules (and those carrying few electrically charged chemical groups) move slower through the medium than smaller molecules (and those with many electrically charge chemical groups).

Coagulation factors are proteins found in blood plasma. Red blood cells (above) are the most familiar components of blood.

electrostatic binding A chemical bond of two atoms or molecules by an electrostatic force (like static electricity) caused by one or more electrons moving from one atom to the other.

eluate Also called elution fractions; the separated components of a mixture that wash out from a chromatography column during elution.

eluent The substance used to recover samples from a chromatography column; sometimes an elution solvent. When a buffering agent is used, it is called an elution buffer. Sometimes a solvent is used and just referred to as the eluent.

elution Washing out; removing adsorbed material with a solvent or buffering agent.

elution profile A graph made to show how much material is being carried out of the column by the eluent in column chromatography over time. The graph will show a number of different peaks; each peak represents a different separated material from the original mixed substance. Also called a chromatogram.

Liquid formulations are most common for biopharmaceuticals.

EM Electron microscopy; in which instruments focus electrons like optical microscopes focus light. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are sometimes used in bioanalytical laboratories.

EMEA European Medicines Evaluation Agency; the agency responsible for regulating biopharmaceuticals in the European Union.

emulsification A process that creates a stable mixture of two liquids that normally would not mix together (such as oil and water) by forcing one to disperse in the other as droplets.

enantiomer Either of a pair of chemical compounds whose molecular structures have a mirror-image relationship to each other (see diastereomer).

encapsidation During formation of a virus particle, the process by which nucleic acid is incorporated (encapsidated) into the viral capsid (see also capsid).

encapsulation To enclose in a capsule, usually one made of a biodegradable polymer.

endogenous Growing or developing from a cell or organism, or arising from causes within the organism.

endonuclease A restriction enzyme that breaks up nucleic acid molecules at specific sites along their length. Such enzymes are naturally produced by microorganisms as a defense against foreign nucleic acids.