| photoaffinity labelling | <technique> A technique for covalently attaching a label or marker molecule onto another molecule such as a protein. The label, which is often fluorescent or radioactive, contains a group that becomes chemically reactive when illuminated usually with ultraviolet light) and will form a covalent linkage with an appropriate group on the molecule to be labelled: proximity is essential. The most important class of photoreactive groups used are the aryl azides, which form short lived but highly reactive nitrenes when illuminated. (31 Dec 1997) |
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| photoaffinity labels | Biologically active molecules which are covalently bound to the enzymes or binding proteins normally acting on them. Binding occurs due to activation of the label by ultraviolet light. These labels are used primarily to identify binding sites on proteins. (12 Dec 1998) |
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| spin labelling | <chemistry, technique> The technique of introducing a grouping with an unpaired electron to act as an electron spin resonance (ESR) reporter species. This is almost invariably a nitroxide compound (N O) in which the nitrogen forms part of a sterically hindered ring. (18 Nov 1997) |
| drug labelling | Use of written, printed, or graphic materials upon or accompanying a drug container or wrapper. It includes contents, indications, effects, dosages, routes, methods, frequency and duration of administration, warnings, hazards, contraindications, side effects, precautions, and other relevant information. (12 Dec 1998) |