The cross-linking of tubulin with imidoesters

Abstract

Tubulin [from porcine brain] was reacted with a monofunctional imidoester, ethyl acetimidate, and 3 bifunctional imidoesters ranging in extension from 5-10 .ANG.. Extensive cross-linking occurred with the 3 bifunctional reagents resulting in the formation of dimers, trimers, tetramers, pentamers and hexamers. A similar cross-linking pattern was observed with the monofunctional reagent. This type of cross-linking is rarely seen when proteins are reacted with imidoesters. Given that the cross-linking span of ethyl acetimidate is only 3 .ANG. it is reasonable to infer that there are nucleophilic groups in close proximity within the tubulin dimer. Amidinated tubulin is still capable of assembling into microtubules.