Schramm H J, Dülffer T
Adv Exp Med Biol. 1977;86A:197-206. doi: 10.1007/978-1-4684-3282-4_11.
Bifunctional imidoesters are due to their mild reaction especially suitable for the crosslinking of proteins. Most often used are diimidates with a medium span (4 or 6 CH2-groups). Reagents with a wider span might be of interest. In such a case, however, the bridge should be more hydrophilic. Bifunctional imidoesters have, therefore, been prepared from dinitriles NC-(CH2)2-X-(CH2)2-CN; X being -O-, -O-(CH2)n-O- or -O-(CH2)m-O-(CH2)n-O-. The bridge of diimidoesters can also be labelled by coloured or fluorescent groups. Diimidoesters containing -S-S-bonds in the bridge can be cleaved more easily after their reaction with proteins. Dimethyl-3.3' -(8- delta -dithiahexamethylenedioxy)-dipropionimidate, a "long", cleavable and more hydrophilic diimidate, is a promising new reagent. In cases, where HS-(CH2)3-C(=NH)-OCH3- HC1 is is used for crosslinking of proteins, this reagent can possibly be replaced by 2-iminothiolane hydrochloride, a cyclic thioimidate, which is easier to prepare and to handle.
双功能亚胺酯因其温和的反应特性，特别适用于蛋白质交联。最常用的是具有中等跨度（4或6个CH₂基团）的二亚胺酯。具有更宽跨度的试剂可能会受到关注。然而，在这种情况下，桥连部分应该更具亲水性。因此，双功能亚胺酯是由二腈NC-(CH₂)₂-X-(CH₂)₂-CN制备的；其中X为-O-、-O-(CH₂)ₙ-O-或-O-(CH₂)ₘ-O-(CH₂)ₙ-O-。二亚胺酯的桥连部分也可以用有色或荧光基团标记。在桥连部分含有-S-S-键的二亚胺酯与蛋白质反应后更容易裂解。3,3'-（8-δ-二硫杂六亚甲基二氧基）-二丙酸二甲酯亚胺酯，一种“长链”、可裂解且更具亲水性的二亚胺酯，是一种很有前景的新型试剂。在使用HS-(CH₂)₃-C(=NH)-OCH₃·HCl进行蛋白质交联的情况下，该试剂可能会被盐酸2-亚氨基硫杂环戊烷替代，后者是一种环状硫代亚胺酯，制备和操作起来更容易。
