PECTIN ULTRASTRUCTURE I: Pectate Elementary Fibrils

Direct evidence for a supramolecular pectate structure is presented. Both positive and negative staining indicates that these tertiary structures exist as elementary fibrils. In their hydrated form, these elementary fibrils are 30.8 ± 6.2 Å wide and could contain 13 pectate molecules in their cross sectional area. The smaller width observed in the dehydrated form is probably due to the decrease in intermolecular distance on dehydration. These elementary fibrils, as a tertiary structure organizing pectate molecules, are a possible method for stabilization of component molecules of a gel network. They can serve as a basis for explanation of differences in molecular weight determined by end group analysis as compared to other methods.