Abstract
We describe a simple, sensitive affinity technique for the routine measurement of glycosylated plasma proteins in clinical laboratories. The commercially available phenylboronic acid gel used for the chromatography has recently been marketed as a kit for this purpose (Glycogel Test Kit, Pierce Chemical Co). The manufacturers of this kit recommend loading 200 μl neat plasma to each 1 ml gel column. This high loading is to enable the direct measurement of protein in the bound and unbound fractions at 280 nm. This loading is consistent with 10–15 mg protein being added per ml gel. Our results show that protein levels greater than 2 mg per ml gel overload the column. Therefore we used a modification of the more sensitive Bradford procedure to measure protein. The method discriminates between normals (6·29 ± 1·87%) and diabetic patients (12·62 ± 3·36%) and has good precision (CV 4–6%). The results obtained correlate with the colorimetric method using thiobarbituric acid (r = 0·70) and with glycosylated haemoglobin (r = 0·82).