The structure of unimolecular films

Abstract

Surface films one molecule in thickness present the simplest type of molecular mosaic. In this paper, data obtained by means of surface pressure and surface potential methods on films of various proteins are given and applied in an attempt to indicate the probable structure of the protein micelle as it exists in the film state. Gorter and Grendel 1 were the first, with the aid of a Langmuir trough, to examine thin films of proteins and spread the material dispersed in acid or alkaline solutions on the surface of various substrates. This method, ingenious as it was, could not be utilized to obtain homogeneous films in every instance as revealed by the ultramicroscopic examination of protein films spread in this manner by Zocher and Stiebe12 The apparent mean limiting thickness of the films studied by Gorter and Grendel varied from 7.5 to 30.6 A. and appeared to be complicated by the action of the dispersing agent on the proteins and the solubility of a portion of the material. Preliminary results on some protein films have been presented by Hughes, Schulman and Rideal. Recently Hughes and Rideal 4 have examined in detail the behavior of monolayers of gliadin and glutenin. Films formed by spreading the solid material directly from the arm of a quartz fiber microbalance were found to be homogeneous as revealed by surface potential and surface pressure measurements. In the case of gliadin, in which two-thirds of the side chains may be regarded as consisting of the glutamyl residue, they were