Asn Asparagine; one of more than 20 naturally occurring amino acids.

Asp Aspartic acid; one of more than 20 naturally occurring amino acids.

assay A technique (test) for measuring a biological response or for determining characteristics such as composition, purity, activity, and weight.

ATP Adenosine 5'-triphosphate; helps cells conserve and spend energy and often is used in assays of various ATP-dependent enzymes.

attenuated Weakened (attenuated) viruses often used as vaccines; they can no longer produce disease but still stimulate a strong immune response similar to the natural virus. Examples include oral polio, measles, mumps, and rubella vaccines.

AutoBlend In chromatography systems manufactured by Waters, AutoBlend mode allows the automatic blending of up to four buffers, salts, or solvents in accurate proportions reproducibly, which can simplify mobile phase preparation. Any sequence of isocratic, binary, ternary, and quaternary gradients (very useful for SEC) can be used. The technique is useful for routine assays as well as automatic method development or system flushing.

autoradiography A technique that uses X-ray film to visualize radioactively labeled molecules or molecular fragments; used in analyzing the length and number of DNA fragments after separation by gel electrophoresis.

B

Bacillus subtilus A Gram-positive, aerobic, endospore-forming, rod-shaped bacterium commonly found in soil, bodies of water, sewers, and in association with some green plants; the second most common species used in recombinant fermentation; also known for its ability to handle organic waste in other types of biotechnology such as bioremediation.

bacteriophage A virus that infects bacteria, sometimes used as a vector.

bacteriostatic agent A chemical agent that prevents microbes from multiplying but does not reliably kill them. May be used during processing, in raw materials, or in final products, especially multiple dosage medicines.

baculovirus A virus that replicates only in the cells of Lepidopteran insects; it has been genetically engineered to force the insect cells in culture to produce large amounts of a given protein through its natural method of replication, that is, injecting DNA into each cell.

baseline Observations or data used for comparison or as a control.

base pair Two bases on different strands of nucleic acid that join together. In DNA, cytosine (C) always pairs with guanine (G) and adenine (A) always links to thymine (T). In RNA molecules, adenine joins to uracil (U).

basic variant A product variant that exhibits a more positive charge character by IEX or CE than the primary biotherapeutic form.

batch A quantity of a drug substance or drug product with uniform character and quality, within specified limits, produced according to a single manufacturing run during the same cycle of manufacture.

batch culture Large-scale cell culture in which cell inoculum is cultured to a maximum density in a tank or airlift fermentor, harvested, and processed as a batch.

benchtop A term used to distinguish between laboratory-scale or small-scale processes, those that can be performed "on the bench" (in the lab or even on a tabletop) and larger, pilot- or production-scale processes. Benchtop equipment (a "benchtop bioreactor," for example) can fit on a table or in a confined laboratory area.

beta sheet (b-sheet) A structure resulting from the regular, accordion-like folding of polypeptide chains; the chief alternative to the alpha helix.