Abstract
The binding of Cu²� by human serum transferrin was investigated. The kinetics of the reaction of apotransferrin with Cu ²� at saturating levels of NaHCO₃ were consistent with a sequence involving apotransferrin in Cu²� in a second order, bimolecular reaction as the rate limiting step. The observed second order rate constant was 6.25 x 10 � M�¹ s�¹. Cu²� was found to react incompletely with apotransferrin on the basis of the concentration of available binding sites as determined by spectrophotometric titration of apotransferrin with Fe³� -NTA. The removal of Cu²� from Cu²� -transferrin-CO₃²� by sodium citrate, ethylenediamine, [alpha, alpha]'-dipyridyl, nitrotriacetic acid, and bathophenanthroline sulfonate was investigated. With the exception of the reaction involving nitrilotriacetic acid, the removal of Cu²� from Cu²�-transferrin-CO₃²� does not appear to proceed via the formation of a complex involving chelate and Cu²�-transferrin-CO₃²�. Results are presented which provide the first strictly chemical evidence that the two metal binding sites of transferrin are not equivalent.
Cochran, McKendree Thomas (1976). The binding of cupric ion by human serum transferrin. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -182530.