F

Fab Antigen-binding fragment of an immunoglobulin. An IgG Fab is prepared by enzymatic cleavage of the intact tetrameric IgG, and reduction of the inter-chain disul-fide links, and binds one mole of antigen per mole. [See F(ab)'2]

F(ab)'2 Dimeric antigen-binding fragment of an immunoglobulin. An IgG F(ab)'2 is prepared by enzymatic digestion of the intact IgG, which removes the Fc portion of the molecule. F(ab)'2 binds two moles of antigen per mole. (See Fab)

factors (coagulation factors) Protein constituents of blood, numbered according to the order in which they were discovered, which separate out in a traditional fractionation procedure (Cohn fractionation); Factor VIII, for example, is a blood serum protein involved in clot formation that is also called antihemophilic globulin.

Fc Portion of an immunoglobulin molecule that carries various effector functions, such as the ability to bind complement. Important in immunological activities, and separable from the antigen-binding portion by enzymatic or chemical cleavage. (See Fab)

FD&C Act Food, Drug and Cosmetic Ad of 1938; the major legislation regulating such products in the United States. It requires companies to prove that their products are safe before marketing them, extends FDA oversight to cosmetics and therapeutic devices, explicitly authorizes factory inspections, requires standards for food, and adds injunctions to previous penalties of seizure and criminal prosecution for violations of related laws.

FDA United States Food and Drug Administration.

FDA-483 A form prepared at the conclusion of an inspection (without review by FDA management) citing observations that may constitute violations of law, in the opinion of the inspector. Originally intended to inform companies of possible product adulteration so that prompt corrective action could be taken, 483s now list a host of observations. Accessible through the Freedom of Information Act by competitors, potential customers, and the media, 483s can lead to withholding of product approvals, may come into play in due diligence phases of acquisitions and mergers, and can potentially cost companies money.

FDAMA FDA Modernization Act; enacted in November 1997, this amends the FD&C Act to improve (facilitate) the regulation of food, drugs, devices, and biological products.

feedstock Also feed or feed stream; most often the raw broth containing particles to be removed that is placed into a laboratory or manufacturing appliance such as a centrifuge or chromatography column.

feed stream Also feed or feedstock; most often the solution fed into a reaction or separation/purification process.

fermentation Large-scale cultivation of microorganisms or single-celled creatures for industrial purposes, such as to produce therapeutic molecules or specialty foods and beverages.

fermenter A large bioreactor used to grow bacteria or fungi in liquid culture.

fill-and-finish The part of a manufacturing process concerned with packaging a product in its final form.

filter Porous material through which a liquid or gas is passed so that particulates and impurities are held in suspension and removed from the feed stream. Some impurities may pass through.

filtrate The part of a mixture that passes through a filter, also called permeate.

filtration Separation of solid particles from a fluid by passing the mixture through a porous, fibrous, or granular substance.

FISH Fluorescence in situ hybridization; an analytical method in which specific sequences of DNA are labeled with fluorescent molecules, hybridized (amplified), and then detected with a fluorescence microscope.

floe A fluffy aggregate that resembles a woolly cloud.

flocculant A precipitate (floe), sometimes a flaky or fluffy aggregate that resembles a woolly cloud; the aggregation (flocculation) of initially separate cells that form flocs.

flux Usually, the rate of flow. A lower flux means slower flow, usually caused by clogging.