期刊
CHEMICAL SCIENCE
卷 11, 期 3, 页码 879-887出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9sc05260g
关键词
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资金
- National Natural Science Foundation of China [21327902, 21675083, 91753108, 31972917]
- Fundamental Research Funds for the Central Universities [020514380142, 020514380174]
- State Key Laboratory of Analytical Chemistry for Life Science [5431ZZXM1804, 5431ZZXM1902]
- 1000 Plan Youth Talent Program of China
- Program for high-step Entrepreneurial and Innovative Talents Introduction of Jiangsu Province
- Technology Innovation Fund Program of Nanjing University
- Excellent Research Program of Nanjing University [ZYJH004]
In the formation of coordination interactions between metal ions and amino acids in natural metalloproteins, the bound metal ion is critical either for the stabilization of the protein structure or as an enzyme co-factor. Though extremely small in size, metal ions, when bound to the restricted environment of an engineered biological nanopore, result in detectable perturbations during single channel recordings. All reported work of this kind was performed with engineered alpha-hemolysin nanopores and the observed events appear to be extremely small in amplitude (similar to 1-3 pA). We speculate that the cylindrical pore restriction of alpha-hemolysin may not be optimal for probing extremely small analytes. Mycobacterium smegmatis porin A (MspA), a conical shaped nanopore, was engineered to interact with Ca2+, Mn2+, Co2+, Ni2+, Zn2+, Pb2+ and Cd2+ and a systematically larger event amplitude (up to 10 pA) was observed. The measured rate constant suggests that the coordination of a single ion with an amino acid follows hard-soft-acid-base theory, which has never been systematically validated in the case of a single molecule. By adjusting the measurement pH from 6.8 to 8.0, the duration of a single ion binding event could be modified with a similar to 46-fold time extension. The phenomena reported suggest MspA to be a superior engineering template for probing a variety of extremely small analytes, such as monatomic and polyatomic ions, small molecules or chemical intermediates, and the principle of hard-soft-acid-base interaction may be instructive in the pore design.
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