Copper(II) binding properties of hepcidin
#MMPMID26883683
Kulprachakarn K
; Chen YL
; Kong X
; Arno MC
; Hider RC
; Srichairatanakool S
; Bansal SS
J Biol Inorg Chem
2016[Jun]; 21
(3
): 329-38
PMID26883683
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Hepcidin is a peptide hormone that regulates the homeostasis of iron metabolism.
The N-terminal domain of hepcidin is conserved amongst a range of species and is
capable of binding Cu(II) and Ni(II) through the amino terminal copper-nickel
binding motif (ATCUN). It has been suggested that the binding of copper to
hepcidin may have biological relevance. In this study we have investigated the
binding of Cu(II) with model peptides containing the ATCUN motif, fluorescently
labelled hepcidin and hepcidin using MALDI-TOF mass spectrometry. As with
albumin, it was found that tetrapeptide models of hepcidin possessed a higher
affinity for Cu(II) than that of native hepcidin. The log K 1 value of hepcidin
for Cu(II) was determined as 7.7. Cu(II) binds to albumin more tightly than
hepcidin (log K 1 = 12) and in view of the serum concentration difference of
albumin and hepcidin, the bulk of kinetically labile Cu(II) present in blood will
be bound to albumin. It is estimated that the concentration of Cu(II)-hepcidin
will be less than one femtomolar in normal serum and thus the binding of copper
to hepcidin is unlikely to play a role in iron homeostasis. As with albumin,
small tri and tetra peptides are poor models for the metal binding properties of
hepcidin.
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