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This study was undertaken to distinguish between normal and diabetic subjects by lectin-glycated hemoglobin interaction. The quantitative precipitin method was performed for the interaction between glucose-specific lectin Concanavalin A (Con A) and the glucose-containing RBC-lysate for the estimation of calculated HbA1c% from a standard curve. The standard curve was prepared by plotting the optical density of the precipitin for the interaction of standard HbA1c concentration with Con A against HbA1c reference standard. The absorbance range of the precipitate was 0.14-0.20 in normal subjects and the corresponding calculated HbA1c% along with plasma glucose (mg/dl) levels was 4.1-5.8% and 82-101 mg/dl respectively. Higher absorbance values, 0.22-0.42, were obtained in diabetic patients when the calculated HbA1c% was 6.3-12.2% and plasma glucose level was 120-292 mg/dl. Almost similar results were observed for HbA1c% (6.1-11.9%) of the same diabetic samples measured by conventional ion-exchange high performance liquid chromatography (HPLC). Excellent correlation coefficients of the two methods from regression analysis graph for normal (r = 0.98) and diabetic patients (r = 0.99) were observed. Furthermore, nondiabetic and diabetic hemoglobin variant subjects showed similar HbA1c% by our lectin-based assay when compared with standard HPLC method. We conclude that this lectin-based assay may be adopted to estimate glycated hemoglobin level in differentiating between normal and diabetic patients. This assay offers a good correlation with standard HPLC method. Moreover; the method is convenient, cheap, and needs no sophisticated instruments.

The present investigation was designed to distinguish prostate cancer and benign prostate hyperplasia by lectin-prostate specific antigen (PSA) binding.The quantitative precipitin method of concanavalin A (Con A)-carbohydrate interaction was explored with the serum PSA of patients suffering from prostatic complications.The carbohydrate content in the precipitate after binding of Con A with serum PSA of prostate cancer was significantly lower than that of benign prostate hyperplasia. This may be due to altered sugar chain structure or less glycosylation of PSA in prostate cancer.We conclude that a serum value3.0 microg/ml of the carbohydrate content of Con A-PSA precipitate indicates strong suspicion for prostate cancer and this cut off level is effective in reducing the rate of unnecessary biopsies in men with total PSA value between 4.0 to 10.0 ng/ml.

A lectin from early long pod var. of Vicia faba seed has been purified to homogeneity on chitin. The purified lectin is shown to be homogeneous in nature by Bio Gel P - 150 gel filtration, fast protein liquid chromatography and polyacrylamide gel electrophoresis. The lectin is a glycoprotein with molecular weight of 51,000. The lectin molecule is possibly composed of two types of subunits devoid of any covalent linking through sulfhydryl groups, with molecular weights 9,000 and 15,000 respectively in the ratio 2:2. The purified lectin shows a high affinity for N-acetyl-D-glucosamine (GlcNAc). Amino acid analyses show that cysteine and methionine are absent, and a high proportion of aspartic acid and glutamic acid are present in the protein molecule. The extinction coefficient of the purified lectin is 7.22. The lectin behaves as a 'cold agglutinin' displaying stronger agglutination than the naturally occurring ABO agglutinin in the cold.