light chain

light chain

n.

The smaller of the two types of polypeptide chains in immunoglobulins, consisting of an antigen-binding portion with a variable amino acid sequence, and a constant region with an amino acid sequence that is relatively unchanging.

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light chain (L chain),

a subunit of an immunoglobulin molecule composed of a polypeptide chain of about 22,000 daltons, or atomic mass units. An example of a light chain is a Bence Jones protein molecule associated with multiple myeloma.

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chain

a collection of objects linked together in linear fashion, or end to end, as the assemblage of atoms or radicals in a chemical compound, or an assemblage of individual bacterial cells.

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chain binomial model

model of an outbreak of an infectious disease in which the outbreak is depicted as a series of steps with a binomial statement of the probability of an outcome at each step.

branched chain

an open chain of atoms, usually carbon, with one or more side chains attached to it.

heavy chain

any of the large polypeptide chains of five classes that, paired with the light chains, make up the antibody molecule. Heavy chains bear the antigenic determinants that differentiate the immunoglobulin classes. See also heavy-chain disease.

J chain

a polypeptide occurring in polymeric IgM and IgA molecules.

light chain

either of the two small polypeptide chains (molecular weight 22,000) that, when linked to heavy chains by disulfide bonds, make up the antibody molecule; they are of two types, kappa and lambda, which are unrelated to immunoglobulin class differences.

light chain disease

the overproduction of immunoglobulin light chain molecules by certain B cell tumors (plasmacytomas). See monoclonal gammopathy.

obstetric chain

used in obstetrics in cattle and horses to snare extremities and for traction. Made of rustproof metal with links designed not to kink or to jam. They have a loop link at each end to facilitate single-handed formation of a loop. The links are shaped so that the ring-grip handles used for traction will grip at any point and stay put with the strongest pull.

chain shank

a leather lead with a short section of chain at the proximal end. It can be placed over the horse's nose, through the mouth or across the upper gum for greater control.

side chain

a chain of atoms attached to a larger chain or to a ring.

stallion chain

strong chain, 1-2 ft (0.5 m) long, at the end of a solid lead. For leading a stallion with little chance of his biting through the lead.

chain termination method

See sanger-coulson method.