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Adsorption behaviour of globular proteins at the water/mercury interface
Author(s) -
Scheller Frieder,
Jänchen Michael,
Prümke HansJörg
Publication year - 1975
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1975.360140802
Subject(s) - chemistry , globular protein , adsorption , dropping mercury electrode , mercury (programming language) , polarography , electrode , crystallography , molecule , lysozyme , protein adsorption , inorganic chemistry , biochemistry , organic chemistry , electrochemistry , computer science , programming language
The adsorption of globular proteins at solid/liquid or liquid/liquid interfaces provides evidence of unfolded molecular conformation. Proteins with high apolar character are strongly unfolded, while those with high polar character are generally incompletely unfolded. Structural changes of globular proteins at adsorption on mercury electrodes were studied by ac polarography and capacity–time curves. The surface area per molecule of nine globular proteins was determined from the adsorption kinetics at the dropping mercury electrode. For all the proteins investigated, this value was greater than the maximal molecular cross section of the native proteins. The surface area was about 19 Å 2 per amino acid residue, which coincides with the value for unfolded proteins at the water/air interface. Differences between dropping mercury electrode and hanging drop mercury electrode occurred only with lysozyme and phosphorylase; for the other proteins, the structure of the adsorption layer was independent of the time of interaction at the electrode. Since not all of the reducible groups of the adsorbed proteins come into contact with the electrode, the flattening should be incomplete.