Protective effect of albumin on the glycation of hemoglobin

Glycated proteins such as hemoglobin and albumin are very important for diagnosing insulin resistancerelated conditions(IRRC; e.g. type 2 diabetes mellitus, cardiovascular diseases, nephropathy andretinopathy). The albumin glycation assay indicates the average level of blood glucose in past 2-3weeks[1]; albumin also protects other proteins against glycation. A special kind of glycated hemoglobincalled HbA1c was discovered in the 60s[2]. HbA1c indicates average blood sugar levels in past 3-4months.Currently the HbA1c assay is used as a gold standard for confirming IRRC[3]. To date theprotective effect of albumin onhemoglobin has not been investigated. We first extracted hemoglobin fromhuman whole blood. Then hemoglobin wasco-incubated with fructoseat different concentrations ofalbumin. Hemoglobin concentration was adjusted close to the physiological level (15 μL) while fructoseconcentration wasthat of diabetic state (30 mM). Albumin was incubated with different concentrations:Low, normal and high related to physiological state(0.5, 0.75 and 1.25 mM respectively).The first controlwas only hemoglobin and the second control was hemoglobin with fructose. Incubation period was 21days. Samples were taken every 5 days with 3 repetitions and the absorption of hemoglobin from 200 to650 nM was measured.The hemoglobin absorption spectrum has a peak from 350 to 450 nm.Glycationreduces total absorption within this range. We found that albumin prevented absorption drop withinhemoglobin absorption curve.These results suggest that albumin has a protective effect against glycationof the hemoglobin.

کلیدواژه ها:

HbA1c ، Glycation ، Hemoglobin ، Albumin ، Diabetes ، Insulin resistance