期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：10
页码：6216-6220
DOI：10.1073/pnas.78.10.6216
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The anomalous dispersion of iron at its K-absorption edge in small-angle scattering of an aqueous solution of hemoglobin has been used to establish the geometrical arrangement of the four iron atoms in this protein. Although the anomalous contributions are 0.001-0.01 of the total scattering, experiments with synchrotron radiation from the storage ring DORIS have shown that these effects can be measured with an average precision of approximately 10% at each of the 50 points of the scattering curve. The anomalous scattering represents the convolution of the whole structure with the configuration of the four iron atoms of hemoglobin. Analysis in terms of multipoles suggests that tetrahedral symmetry of both the subunit arrangement and the iron structure is a dominant feature. The mean distance between the iron atoms of 26 A derived from this experiment compares well with that derived from crystallographic data.
