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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1976 Apr;73(4):1193–1195. doi: 10.1073/pnas.73.4.1193

Electron probe x-ray analysis of single ferritin molecules.

H Shuman, A P Somlyo
PMCID: PMC430227  PMID: 1063401

Abstract

Single molecules and groups of two or three ferritin molecules were subjected to electron probe x-ray microanalysis in a transmission electron microscope equipped with a liquid nitrogen cooled stage. Significant Fe Kalpha peaks were generated during 100-sec counts when single ferritin molecules were excited with a probe current of 0.35 nA/60 nm spot, less than the maximal current available in a thermionic gun. There was a linear relationship between the number of ferritin molecules analyzed and count rates. The experimental results are compared to the theoretically calculated Fe Kalpha yields and to the results of Isaacson and Johnson [(1975) Ultramicroscopy I, 33-52] with electron energy loss analysis. We conclude that current state of the art electron probe x-ray analysis can realize the theoretically predicted sensitivity of the method, and estimate 0.9 X 10(-19) g of Fe as the minimal mass detectable with maximal (thermionic) probe current during a 100-sec count and with 95% confidence.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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