Resources

List by Alphabet: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

a Related Biological Terms:

detoxification

The chemical modification by oxidation, methylation, glycosylation, etc. of a xenobiotic to render it innocuous.

dextran

A branched-chain storage polysaccharide of microbial origin.

dextro-rotation

(see optical rotation)

diagonal electrophoresis

A method for identification of a particular kind of peptide in a mixture by identical electrophoretic steps, the second at a 908 angle to the first, with a chemical modification introduced between the steps. An example is the identification of tyrosine-bearing peptides in a mixture of peptides by treatment of the products of paper electrophoresis with iodine vapour to iodinate the tyrosine residues before the second electrophoresis. Iodotyrosine peptides are then identified as those that deviate from the diagonal formed by all the other peptides when they are visualized by, for instance, the ninhydrin reaction. Related tool: real time pcr

dialysis

A technique for the separation of macromolecules from smaller molecules by placing them within a semi-permeable membrane, such as Cellophane, separating them from a large volume of water. Only the low-molecular-mass diffusible molecules cross the membrane and pass into the larger volume; the macromolecules are confined to their original space. Equilibrium dialysis is the technique of quantification of binding capacity and affinity by dialysis of a macromolecule against various concentrations of a ligand and subsequent measurement of the final concentrations of bound and free ligand within the dialysis chamber and free ligand outside it. Related tool: molecular biology tools

diamagnetic

Descriptive of a compound or chemical group (usually one that contains no unpaired electrons) that is not affected by a magnetic field. (see also paramagnetic)

diaphorase

An enzyme that transfers electrons from NADH to a dye or to ferricyanide.

diastereoisomer

One of two or more compounds that differ from each other at one or more asymmetrical centres, e.g. D-erythrose and D-threose. (see also enantiomer; epimer; stereoisomer)

diauxie

bacterial growth in two stages which occurs when the bacteria are grown on two carbon sources, e.g. glucose and xylose. The first phase corresponds to consumption of one compound, followed by a lag phase until enzymes for the assimilation and metabolism of the second compound are produced. Roseman, S. and Meadow, N.D. (1990) J. Biol. Chem. 265, 2993-2996

difference Patterson map

An interim stage in the solution of a molecular structure from X-ray crystallographic data. Using only the intensities due to heavy atom reflections obtained by subtraction of the reflections of the protein from those of an isomorphous replacement, Fourier analysis calculates the vectors between heavy atoms. Their display is the difference Patterson map. This map may then be used to calculate the relative positions of the heavy atoms. (see also Fourier transformation; phase problem) Related tool: molecular biology tools

< 55 56 57 58 59 60 61 62 63 64 65 > Total Pages 251

If you know of any terms that have been omitted from this glossary that you feel would be useful to include, please send detail to the Editorial Office at GenScript: website@genscript.com

If your term is adopted, we will send 1,000 EzCoupon points to your GenScript account.