Observation of albumin resonances in proton nuclear magnetic resonance spectra of human blood plasma: N-terminal assignments aided by use of modified recombinant albumin.
Two-dimensional total shift correlation spectroscopy (TOCSY) and double-quantum-filtered phase-sensitive homonuclear shift-correlated spectroscopy (DQF-COSY) 1H NMR spectra are used to assign peaks for about one sixth of the amino acids residues of isolated human serum albumin (67 kDa) to amino acid types. Sequential assignments are presented for 1H NMR resonances of the N-terminal residues Asp1, Ala2 and His3 of human serum albumin (HSA). These are based on pH-dependent chemical shifts reflecting the titrating N-terminal NH2 and the His3 imidazole ring, in addition to DQF-COSY and TOCSY experiments. Studies of variant recombinant human albumin with Asp1 deleted, rHA(2-585), aided the assignments. The structural nature of the N-and C-termini of HSA are discussed and pKa values of 7.9 and 6.3 were determined for the N-terminal amino group and His3 imidazole ring, respectively. About 20 spin systems for albumin, including those for the N-terminal amino acids, were assigned in 1H NMR spectra of blood plasma buy comparison with isolated albumin. Resonances for lipids within lipoproteins and also several low molecular mass components can also be assigned in 2D TOCSY 1H NMR spectra of plasma.
Harris
R
R
Delta Biotechnology Limited, Nottingham, UK.
Patel
S U
SU
Sadler
P J
PJ
Viles
J H
JH
D000595:Amino Acid Sequence; D006801:Humans; D008074:Lipoproteins / Q000097:blood; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry; D012709:Serum Albumin / Q000737:chemistry*
D008074:Lipoproteins; D011994:Recombinant Proteins; D012709:Serum Albumin