Electrostatic repulsion between molecules of like charge can be misinterpreted as binding

FEBS Letters

Klee, Claude B.¹  Stemmer, Paul¹ 

[1] Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA

关键词: EDTA binding;    Electrostatic repulsion;    Calmodulin;    α-Lactalbumin;    Chelator;   

DOI  :  10.1016/0014-5793(90)80509-H

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Spectroscopic methods have shown that Ca²⁺ chelators interact with Ca²⁺-binding proteins. These spectral alterations have been interpreted as evidence for the binding of chelator by the proteins. We show by direct examination of EDTA interaction with calmodulin and α-lactalbumin that these proteins repel EDTA rather than bind it. The repulsion is reduced by increased salt concentration but is unaffected by Ca²⁺ binding to the proteins. The acidic protein, α-lactalbumin, repells the negatively charged EDTA and inorganic phosphate whereas the basic protein, lysozyme, repells the positively charged spermine. Thus, spectroscopic changes induced by negatively charged Ca²⁺ chelators on negatively charged Ca²⁺-binding proteins are due to electrostatic repulsion, and not to binding. These observations underscore the possible pitfalls of using spectroscopic methods alone to analyze protein-ligand interactions.

【 授权许可】

Unknown