Effect of lactoferrin on the ferroxidase activity of ceruloplasmin.
The effects of various forms of lactoferrin (Lf) interacting with ceruloplasmin (Cp, ferro-O2-oxidoreductase, EC 1.16.3.1) on oxidase activity of the latter were studied. Comparing the incorporation of Fe3+ oxidized by Cp into Lf and serum transferrin (Tf) showed that at pH 5.5 apo-Lf binds the oxidized iron seven times and at pH 7.4 four times faster than apo-Tf under the same conditions. Apo-Lf increased the oxidation rate of Fe2+ by Cp 1.25 times when Cp/Lf ratio was 1 : 1. Lf saturated with Fe3+ or Cu2+ increased the oxidation rate of iron 1.6 and 2 times when Cp to holo-Lf ratios were 1 : 1 and 1 : 2, respectively. Upon adding to Cp the excess amounts of apo-Lf (Cp/apo-Lf < 1 : 1) or of holo-Lf (Cp/holo-Lf < 1 : 2) the oxidation rate of iron no longer changed. Complex Cp-Lf demonstrating ferroxidase activity was discovered in breast milk.
Sokolov
A V
AV
Institute for Experimental Medicine, Russian Academy of Medical Sciences, St. Petersburg, 197376, Russia. biochem@nm.ru
Pulina
M O
MO
Zakharova
E T
ET
Shavlovski
M M
MM
Vasilyev
V B
VB
D001059:Apoproteins / Q000378:metabolism; D002570:Ceruloplasmin / Q000378:metabolism; D005260:Female; D006801:Humans; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007781:Lactoferrin / Q000378:metabolism / Q000494:pharmacology*; D008895:Milk, Human / Q000201:enzymology / Q000378:metabolism; D010084:Oxidation-Reduction
D001059:Apoproteins; D007501:Iron; D002570:Ceruloplasmin; D007781:Lactoferrin