Susceptibilities of lactoferrin and transferrin to myeloperoxidase-dependent loss of iron-binding capacity.
Apolactoferrin and apotransferrin lost their ability to subsequently bind iron when exposed to an excess of either HOCl or myeloperoxidase plus H2O2 and Cl-. Apolactoferrin, however, was more resistant than apotransferrin. By oxidizing a mixture of the two proteins, then separating them by immunoprecipitation, the difference in susceptibility was shown to be due to the greater reactivity of transferrin iron-binding groups, rather than protective groups on the lactoferrin molecule. The iron-saturated proteins were much more resistant to oxidative modification than the apoproteins. The greater resistance of apolactoferrin should be advantageous for maintaining its iron binding capacity when co-released with myeloperoxidase and reactive oxygen species from stimulated neutrophils.
Winterbourn
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CC
Department of Pathology, Christchurch School of Medicine, Christchurch Hospital, New Zealand.
Molloy
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AL
D001059:Apoproteins / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D003512:Cyclohexanones / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D006997:Hypochlorous Acid / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007781:Lactoferrin / Q000378:metabolism*; D007782:Lactoglobulins / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism*; D011485:Protein Binding; D014168:Transferrin / Q000378:metabolism*
D001059:Apoproteins; D002712:Chlorides; D003512:Cyclohexanones; D007782:Lactoglobulins; D014168:Transferrin; D006997:Hypochlorous Acid; C006991:chlorodimedone; D006861:Hydrogen Peroxide; D007501:Iron; D009195:Peroxidase; D007781:Lactoferrin