A study of positive staining for electron microscopy using collagen as a model system—III. The effect of suberimidate fixation

Abstract

Collagen is used as a model system to study the structural effects of the fixative dimethylsuberimidate (DMS) on a protein. Using reconstituted fibrils of type I calf skin collagen(of known amino acid sequence), electron-optical data from positive staining patterns were compared with chemical data by a computer-aided correlation procedure. The results show that, under the conditions used, the reaction between DMS and collagen is specific for the ϵ-amino groups of lysyl and hydroxylysyl residues and that no reaction takes place between DMS and arginyl residues. Other evidence suggests that (unlike glutaraldehyde) no polymerization of the DMS occurs and that a cross-link between the two ϵ-amino groups can only form when they are sufficiently close to be bridged by the DMS monomer.