The N-terminal native sequence tripeptide of alpha-fetoprotein, L-threonyl-L-leucyl-L-histidine N-methylamide, was synthesized and its interaction with Cu(II) ions was investigated by potentiometric titration at 25 degrees C in 0.15 M-NaCl and by visible-absorption, e.p.r. and n.m.r. spectroscopy. Analyses of the results in the pH range 4-10 indicated the presence of multiple complex species in solution: MHL, MH-2L, MHL2, ML2 and MH-1L2, where M, H and L represent metal ion, proton and ligand anion respectively. Only the species MH-2L and MH-1L2 are present in significant amounts at physiological pH. The results of the visible-absorption spectroscopy are consistent with the findings of species distribution that MH-2L is the major complex species detected above physiological pH that has the spectral characteristics of lambda max. = 523 nm and epsilon max. = 98 M-1.cm-1. The nine superhyperfine lines in e.p.r. spectra of the major species MH-2L strongly support the co-ordination of four nitrogen atoms by Cu(II). Both 1H- and 13C-n.m.r. studies suggest that the species MH-2L is a square-planar complex. The results from the equilibrium-dialysis experiments showed that this peptide is able to compete with albumin for Cu(II) ions. At equimolar concentrations of albumin and the peptide, about 52% of the Cu(II) was bound to the peptide. The possibility that alpha-fetoprotein plays an important role as the Cu(II)-transport protein in fetal life is discussed.
Skip Nav Destination
Article navigation
February 1989
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkAdvertising
Research Article|
February 01 1989
Synthesis and copper(II)-binding properties of the N-terminal peptide of human α-fetoprotein
S J Lau;
S J Lau
*Research Institute, The Hospital for Sick Children, Toronto, Ont. M5G 1X8, Canada.
2†Departnient of Biochemistry, University of Toronto, Toronto, Ont. M5S 1A8, Canada
Search for other works by this author on:
J P Laussac;
J P Laussac
‡Laboratoire de Chimie de Coordination, C.N.R.S., 31077 Toulouse Cedex, France
4†Departnient of Biochemistry, University of Toronto, Toronto, Ont. M5S 1A8, Canada
Search for other works by this author on:
B Sarkar
B Sarkar
*Research Institute, The Hospital for Sick Children, Toronto, Ont. M5G 1X8, Canada.
5†Departnient of Biochemistry, University of Toronto, Toronto, Ont. M5S 1A8, Canada
Search for other works by this author on:
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1989 London: The Biochemical Society
1989
Biochem J (1989) 257 (3): 745–750.
Citation
S J Lau, J P Laussac, B Sarkar; Synthesis and copper(II)-binding properties of the N-terminal peptide of human α-fetoprotein. Biochem J 1 February 1989; 257 (3): 745–750. doi: https://doi.org/10.1042/bj2570745
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.