Reactive and Photoreactive Crosslinkers

ABH is relatively insoluble when directly added to water or buffer, and therefore it should be pre-dissolved in DMSO prior to addition of an aliquot to an aqueous reaction medium. Stock solutions at a concentration of 50 mM ABH in DMSO work well. Since both reactive groups on ABH are stable in aqueous environments as long as the solution is protected from light, a secondary stock solution may be made from the initial organic preparation by adding an aliquot to the hydrazide reaction buffer (0.1 M sodium acetate, pH 5.5 O Shannessy et al., 1984 O Shannessy and Quarles, 1985). Make a 1 10 dilution of the ABH/DMSO solution in the reaction buffer. This solution may be stored in the dark at 4°C without decomposition. 

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Of the following amine-reactive and photoreactive crosslinkers, the overwhelming majority use an aryl azide group as the photosensitive functional group. Only a few use alternative photoreactive chemistries, particularly perfluorinated aryl azide, benzophenone, or diazo compounds. For general background information on photoreactive crosslinkers, see Das and Fox (1979), Kiehm and Ji (1977), Vanin and Ji (1981), and Brunner (1993). 

Finally, the small amine-reactive and photoreactive crosslinker, NHS-ASA (Chapter 5, Section 3.1), can be iodinated to provide a non-cleavable radioactive conjugate. 

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