Iceberg Model of the Structure of Globular Protein Adsorption Layers at the Air–Water Interface. Study by the Tritium Planigraphy Technique

Abstract

The organization of the adsorption layers of insulin, pancreatic inhibitor of trypsin, ribonuclease S, lysozyme, myoglobin, carboxypeptidase A, subtilisin, and thermolysin at the air–water interface was studied by tritium planigraphy technique. The location of globular protein molecules relative to the interface was determined for solution concentrations corresponding to the formation of saturated adsorption layers (10–4 M, pH 6). It is established that the fraction of solution surface occupied by protein component is equal to 7–62%. Only a small part of globules with the height from 2 to 19% of their effective diameter is above the solution surface, whereas the main part of globules is submerged into water (the iceberg model).