Determination of serum glycosylated proteins: Comparison of thiobarbituric acid and phenol-sulphuric acid assays
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The estimation of glycosylated proteins is useful in the detection and control of long-standing hyperglycemic conditions. In this paper the content of protein-bound glucose was determined in diabetics by spectrophotometric method with phenol-sulphuric acid (PS) and with thiobarbituric acid (TBA). The amounts of protein-bound glucose obtained with the PS reagent (80.6 +/- 22.8 mmol glucose/g protein) were always considerably higher than those obtained by TEA method (3.71 +/- 1.34 mu mol glucose/g protein). The analysis was made of parameters that might have led to such significant difference. It was shown that in the reaction with PS reagent there was an additional dehydration of carbohydrate released during the hydrolysis of glycosylated proteins. The additional dehydration was due to concentrated sulphuric acid which at higher temperature influenced chromogen formation. On the basis of the results obtained it was concluded that, although the sensitivity of the both methods for standar...d fructose was comparable, TEA method was more reliable than PS method. Therefore, it is recommended in clinical practice.
Keywords:glycosylated proteins / phenol-sulphuric method / thiobarbituric method
Source:Jugoslovenska Medicinska Biohemija, 2000, 19, 4, 411-416
- Soc Medical Biochemists Yugoslavia, Belgrade