A method of reacting a first chemical entity and a second chemical entity to forma conjugate in which the first and second chemical entities are covalently boundwith respect to each other, comprises bringing into simultaneous contact thefirst chemical entity, the second chemical entity and a thiol generator, whereinthe thiol generator reacts with the first chemical entity in a thiolation reactionresulting in formation of a free sulfhydryl group on the first chemical entity,and the free sulfhydryl group reacts with the second chemical entity to form theconjugate, and wherein the second chemical entity is polyvalent with respectto its reactivity with sulfhydryl groups. The present invention primarily differsfrom the prior art in that no separation step is involved between reaction of thethiol generator and first chemical entity and reaction with the second chemicalentity. The invention also provides a conjugation kit.
