Nonrandom distribution of iron in circulating human transferrin
O Zak and P Aisen
By combining the urea gel electrophoresis technique of Makey and Seal with
Western immunoblotting, a method has been developed for analyzing the
distribution of iron between the two sites of circulating human
transferrin. The new method avoids exposure of samples to a nonphysiologic
pH that may promote removal or redistribution of iron from the protein;
this facilitates examination of multiple samples at one time. Analysis of
21 freshly drawn specimens from normal human subjects confirms previous
reports that iron is not randomly distributed in the specific sites of
transferrin. Rather, there is a considerable range in the ratio of
occupancies of N-terminal and C- terminal sites (N:C ratio), from 0.31 to
6.87 in the present study, with the N-terminal site predominantly occupied
in most subjects. The N:C ratio correlates modestly with serum iron
concentration (r = .54). Possible flaws in studies indicating a random
occupancy of the specific sites of circulating transferrin may lie in the
low pH to which samples may be exposed during procedures based on
isoelectric focusing or in drawing inferences from data considering only
total monoferric transferrin rather than the two distinguishable monoferric
species.
Volume 68,
Issue 1,
pp. 157-161,
07/01/1986
Copyright © 1986 by The American Society of Hematology
