accelase
A mixture of enzymes that hydrolyse proteins, used to shorten the maturation time of cheeses and intensify the flavour of processed cheese.
active transport
The movement of an ion or molecule across a cell membrane against a concentration or electrochemical gradient. The process requires specific enzymes and energy supplied by ATP.
albumin
(al-bew-min)a protein that is soluble in water and coagulated by heat. serum a. a protein found in blood plasma that is important for the maintenance of plasma volume.
allosteric
Applied to a protein molecule that has two or more sites at which it can bind (combine) with other molecules, such that binding with one influences its binding with another. Some (allosteric) ...
allosteric enzyme
A regulatory enzyme whose catalytic activity is modified by the noncovalent attachment of a specific metabolite to a site on the enzyme other than the catalytic site.
allozyme
Any one of a number of different forms of the same enzyme that are coded by different alleles at the same locus.
alpha amino acid
An amino acid in which the amino group is attached to the number two, or ‘alpha’ carbon, adjacent to the carboxyl group. Compounds of this type represent the basic building blocks of peptides and ...
alpha helix
The most common form of secondary structure in proteins, in which the polypeptide chain is coiled into a helix. The helical structure is held in place by weak hydrogen bonds between the N-H and C=O ...
amino acid
An organic acid carrying an amino group. Proteins are linear polymers of the l-forms of ~20 common amino acids linked by peptide bonds.
amino acids, sulphur
Two amino acids—methionine and cysteine—contain sulphur in the side-chain; although cysteine is not an essential amino acid, it can only be synthesized from methionine, and it is conventional to ...
amino-acid sequence
The sequence of amino-acid residues in a polypeptide chain that represents the primary structure of a protein. This sequence is unique to each protein and influences the protein's secondary, ...
aminogram
A diagrammatic representation of the amino acid composition of a peptide or protein. A plasma aminogram is the composition of the free amino acid pool in blood plasma.
anabolism
n. the synthesis of complex molecules, such as proteins and fats, from simpler ones by living things. See also anabolic, metabolism.
anaphylaxis
Extreme sensitivity to an allergen, clinically manifest as acute-onset swelling of mucosal tissues including the trachea, where it causes life-threatening obstruction of the airway.
antibody
A protein (see immunoglobulin) produced by certain white blood cells (plasma cells) in response to entry into the body of a foreign substance (antigen) in order to render it harmless. An ...
antigen
A molecule, normally a protein, glycoprotein, or polysaccharide, usually found on the surface of a cell, which can interact with receptors found on lymphocytes or antibodies. See also immunogen.
apoenzyme
An inactive enzyme that must associate with a specific cofactor molecule or ion in order to function. Compare holoenzyme.
Bacillus thuringiensis
A naturally occurring bacterium that produces a protein which kills caterpillars and some moths and butterflies. It is a biopesticide that is used extensively by the microbial pesticide industry.
