A semi-automated method for determination of glycosylation of plasma proteins using the thiobarbituric acid method is described. Plasma samples (100 μL) and a plasma pool used as a secondary standard were incubated in 0·3 M oxalic acid at 100°C for exactly 2 h. The hydroxymethyl furfural released and the total protein were measured concurrently on a Technicon AAII Autoanalyzer. Addition of 10 or 20 mmol glucose to plasma samples caused a minimal increase in the measured glycosylated protein. Within-batch and between-batch coefficients of variation were 3·1% and 4·9% respectively. The mean glycosylated protein levels for 52 normals and 48 maturity-onset diabetics were (±1SD) 0·96±0·13 and 1·75±0·32 nmol HMF/mg protein/2 h incubation.
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