Kinetics of the release of aluminum from human serum dialuminum transferrin to citrate.
The kinetics of release of Al3+ from human serum dialuminum transferrin (Al2Tf) to citrate were investigated at 37 degrees C, pH 7.4, mu = 0.7 M, by difference UV spectrophotometry. The two metal-binding sites are not identical but behave in a kinetically similar manner to give apparent second-order rate constants of 0.60 and 0.38 M-1 s-1, respectively, for release of the first Al3+ from Al2Tf. The rate constants for release of the second metal ion from the monoaluminum transferrins are 0.27 and 0.12 M-1 s-1. The kinetic scheme for release of A13+ from Al2Tf is therefore similar to that for release of Fe3+ from Fe2Tf, but the rate of constants for metal ion release are between two and four orders of magnitude larger.
Marques
H M
HM
Department of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
D000535:Aluminum / Q000097:blood*; D001665:Binding Sites; D002412:Cations; D002951:Citrates / Q000097:blood*; D019343:Citric Acid; D006801:Humans; D007700:Kinetics; D013056:Spectrophotometry, Ultraviolet; D014168:Transferrin / Q000378:metabolism*
D002412:Cations; D002951:Citrates; D014168:Transferrin; D019343:Citric Acid; D000535:Aluminum