Premium
N‐terminal Glycation of Proteins and Peptides in Foods and in Vivo
Author(s) -
Penndorf Ilka,
Li Changhao,
Schwarzenbolz Uwe,
Henle Thomas
Publication year - 2008
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1433.024
Subject(s) - glycation , chemistry , valine , lysine , hemoglobin , derivatization , peptide , chromatography , biochemistry , acid hydrolysis , high performance liquid chromatography , amino acid , in vivo , glycated hemoglobin , hydrolysis , diabetes mellitus , endocrinology , biology , receptor , type 2 diabetes , microbiology and biotechnology
Specific determination of N ‐(2‐furoylmethyl)valine (FM‐Val) together with furosine in acid hydrolyzates of human hemoglobin of healthy volunteers ( n = 6) and diabetic patients ( n = 14) by means of reversed‐phase HPLC with electrospray ionization–time‐of‐flight mass spectroscopy is reported. Whereas FM‐Val is formed during acid hydrolysis of the N‐terminal hemoglobin adduct N ‐fructosylvaline, furosine results from acid degradation of lysine residues glycated at the ɛ‐amino group. Quantification was based on the use of synthesized isotopomers, namely N ‐[2‐( 13 C 6 )furoylmethyl]valine and N ‐ɛ‐[2‐( 13 C 6 )furoylmethyl]lysine, thus enabling interference‐free detection and calibration. Taking the conversion factors into account, the amount of N‐terminally bound N ‐fructosylvaline in human hemoglobin was between 518 and 774 pmol/mg protein for healthy volunteers and between 586 and 1426 pmol/mg protein for diabetic patients. Derivatization at the side chain of peptide‐bound lysine residues to N ‐ɛ‐fructosyllysine was from 1156 to 1753 pmol/mg protein for healthy controls and from 1191 to 2409 pmol/mg protein for diabetics. For these patients, the amount of N ‐fructosylvaline showed good correlation with the values for HbA 1c . The significantly higher relative extent of glycation at the N terminus compared to side‐chain glycation points to a specific and intraindividual capacity for enzymatic deglycation in human erythrocytes, which can be assessed using the proposed method.