A new HPLC-based assay for the measurement of fructosamine-3-kinase (FN3K) and FN3K-related protein activity in human erythrocytes

• Published in: Clinical chemistry and laboratory medicine Vol. 52; no. 1; pp. 93 - 101
• Main Authors: Hellwig, Anne, Scherber, Anja, Koehler, Carsta, Hanefeld, Markolf, Henle, Thomas
• Format: Journal Article
• Language: English
• Published: Germany De Gruyter 01.01.2014
• Subjects: Aged; Chromatography, High Pressure Liquid; diabetic complications; Erythrocytes - enzymology; Erythrocytes - metabolism; Female; fructosamine-3-kinase (FN3K); fructosamine-3-kinase-related protein (FN3K-RP); glycation; Hexoses - analysis; Hexoses - chemical synthesis; Hexoses - metabolism; Humans; Lysine - analogs & derivatives; Lysine - analysis; Lysine - chemical synthesis; Lysine - metabolism; Male; Middle Aged; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Substrate Specificity
• ISSN: 1434-6621; 1437-4331; 1437-4331
• DOI: 10.1515/cclm-2012-0853

An impact on glycation, and possibly on diabetic complications, is attributed to fructosamine-3-kinase (FN3K) and its related protein (FN3K-RP) because they degrade Amadori compounds in vivo. Little is known about individual differences in FN3K-RP activity, which might contribute to an individual risk for diabetic complications. An HPLC-based activity assay for FN3K-RP in erythrocytes with the substrate -α-hippuryl- -ε-psicosyllysine was developed. The activities of FN3K and FN3K-RP were also analysed in erythrocytes of 103 consecutive participants of a health-care survey amongst a high-risk group for diabetes. The potential associations of these activities with the subjects’ health background (anthropometric data, glucose tolerance and HbA , blood lipids, history of metabolic diseases in the subjects and their families, and medication) were examined. The interindividual variability of FN3K-RP is less pronounced than that of FN3K [60–135 vs. 2.8–12.5 mU/g haemoglobin (Hb)]. No correlations with age, sex, body weight, blood cholesterol, or plasma glucose in an oral glucose tolerance test were observed. Subjects with kidney disease had higher activity of mainly FN3K-RP [111±15 vs. 98±18 mU/g Hb, mean±standard deviations (SDs), n=16 vs. 87, p=0.009], whereas subjects whose parents or siblings had a stroke showed lower FN3K activity (6.2±1.6 vs. 7.1±1.8 mU/g Hb, mean±SD, n=24 vs. 66, p=0.040). There is a likely impact of FN3K and FN3K-RP on the glycation cascade in vivo with potential positive and negative effects. The new screening method enables further studies to elucidate the function and importance of FN3K-RP.