Measurements of attractive forces between proteins and end-grafted poly (ethylene glycol) chains
Sheth, S.R.; Leckband, D.
Proceedings of the National Academy of Sciences of the United States of America 94(16): 8399-8404
ISSN/ISBN: 0027-8424 PMID: 9237988 DOI: 10.2307/42868
The molecular forces between streptavidin and lipid bilayers with grafted Mr 2,000 poly(ethylene glycol) (PEG) were directly measured using a surface force apparatus. The forces were repulsive at low compressive loads, but they became attractive after the proteins were pressed into the polymer layer at higher loads. The strength of the adhesion was reflected by the fact that separation of the streptavidin and PEG caused the detachment of anchored polymer from the supporting membrane. The properties of the grafted chains were altered by these interactions. The polymer continued to bind protein for many hours after the onset of attraction. Protein denaturation was not responsible for the changes seen.