Search

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 method has been developed to separate and identify thyroglobulin autoantibody (TgAb) and thyroid peroxidase autoantibody (TPOAb) in serum obtained from normal and autoimmune thyroid diseases using phenyl Sepharose CL-4B hydrophobic column. The protein peaks obtained from hydrophobic column were identified as TgAb and TPOAb by comparing the elution profile of commercially purified standard thyroid autoantibodies. The similarity of the inhibitory effects of eluted proteins and of standard thyroid autoantibodies on lectin concanavalin A-RBC interaction confirmed the separation of TPO-Ab and TgAb by the hydrophobic, column. The eluted fractions from the hydrophobic column were estimated by the radio immunoassay (RIA) to confirm the presence of both auto-antibodies. This hydrophobic column method offers an advantage of visual inspection of this autoantibodies by graphic representation of peak height along with their estimation in autoimmune thyroid disorders.

Background : A sugar-binding protein, lectin, was identified in the cystic fluid of brain tumor (glioma). Methods : The protein was purified by high performance liquid chromatography. Results : The molecular weight of the lectin was 29 kDa. The activity of the purified protein was inhibited strongly by p -nitro-β- d -galactose and asialofetuin. The lectin activity was not Ca 2+ - or Mg 2+ -dependent. The antiserum of this pure lectin specifically cross-reacted in the cerebrospinal fluid (CSF) of glioma tumor patients. The same antibody had no reaction with CSF of other neurological patients, normal rat brain tissue extract, oncofetal antigens such as alpha fetoprotein (AFP), carcinoembryonic antigen (CEA), plant lectins, and other body fluids like plural and ascites. Conclusions : This antilectin antibody may be useful in the evaluation of patients with primary brain tumor (glioma).

The erythroagglutinating activity of purified Vicia faba lectin was enhanced in the presence of gums; gum guar caused the highest enhancement. Circular dichroism probe demonstrated 40-57% beta-conformation and 4-23% alpha-conformation of the lectin at pH 7.2 depending upon the analytical methods used. The beta-conformations of untreated and modified V. faba lectins were increased in the presence of gums. The mixing of gum guar with lectin and with modified lectin, respectively, led to the highest values of beta-conformational change in the protein molecule, thereby increasing the number of receptor sites of the lectin molecule. The enhancement of the activity of V. faba lectin in the presence of gum guar might be due to the conformational change of the protein molecule.

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.

On binding toVicia faba lectin, the fluorescence of 4-methylumbelliferyl-α-D-glucoPyranoside was quantitatively quenched showing that the interaction of 4-methylumbelliferyl-α-D-glucoPyranoside took Place in a binding environment. The binding of the fluorescent sugar was saccharide sPecific as evidenced by the reversal of 4-methylumbelliferyl-α-D-glucoPyranoside fluorescence quenching by D-fructose. The association constant,K a, values for the 4-methylumbelliferyl-α-D-glucoPyranoside was determined by comPetition study emPloying reversal of fluorescence quenching of 4-methylumbelliferyl-α-D-glucoPyranoside by D-fructose. TheK a value obtained for D-fructose was 1.07 ±0.03 X 104 M-1 and for 4-methylumbelliferyl-α-D-glucoPyranoside was 1.60 ±0.05 X 104 M-1 at 15°C. TheK a values of 2.51 ±0.06 X 104M-1, l.26 ±0.02 X 104 M-1 and 0.56 ±0.01 X 104M-1, resPectively at 10°, 20° and 30°C were obtained from the ChiPman equation. The relative fluorescence quenching, ΔF a, at infinite concentration of the free saccharide sites ofVicia faba lectin [P′] was 93.5% at 30°C and the binding constant for 4-methylumbelliferyl-α-D-glucoPyranoside lectin interaction as derived by Yank and Hanaguchi equation was 0.63 ±0.01 X 104M-1.

Vicia faba lectin contained 40-57% beta-conformation, 4-23% alpha-conformation along with random coil at pH 7.2 depending upon the analytical methods used. The percentage of beta-conformation increased with the addition of N-acetyl-D-glucosamine or methyl alpha-D-mannopyranoside. The structural transitions of V. faba lectin were affected by alkali at pH 9.6 and 10.6. Binding constants and free energy changes for the interaction between V. faba lectin and N-acetyl-D-glucosamine and methyl alpha-D-mannopyranoside were estimated at pH 7.2 using the c.d. and fluorescence methods.

Human erythrocyte specific lectin was isolated from the seeds ofErythrina variegata Linn. var.orientalis Linn. Merrill. The lectin preferentially agglutinated erythrocytes in the sequence of O>B>A = AB. The lectin was purified 19-fold by affinity chromatography on acid treated sepharose 4B with an yield of 81%. The purified lectin was found homogeneous on polyacrylamide gel electrophoresis. The erythroagglutination reaction was inhibited by N-acetyl-D-galactosamine, D-galactose and lactose at very low concentration. The haemagglutination by the purified lectin was not inhibited by different hexose and pentose sugars even at high concentration. The purified lectin was a glycoprotein and agglutinated leucocytes at 3 μg protein concentration. The lectin induced transformation of peripheral blood lymphocytes in cultures.

Two lectins, an N-acetylgalactosamine-binding lectin, lectin-I, which reacts specifically with human erythrocytes of blood group A, and a galactose-binding lectin, lectin-II, which is specific for human blood group B erythrocytes, have been isolated and purified from rice bean, Phaseolus calcaratus syn. Vigna umbellata , by a salt solubility pH-dependent method, chromatofocusing and high-performance liquid chromatography. The homogeneity of the lectins was determined by liquid chromatography and polyacrylamide gel electrophoresis. The purified lectin-I of molecular mass 80 000 is possibly composed of two subunits of molecular mass ca. 18 000 and 22 000, respectively, whereas lectin-II of molecular mass 100 000 appears to be composed of a monomeric protein of molecular mass 25 000. One endogenous lectin-binding protein was also isolated and purified by liquid chromatography. The endogenous lectin-binding protein of molecular mass 40 000 affects the activity of the A-group specific lectin more than that of the B-group specific lectin. The endogenous lectin-binding protein appears to be composed of a monomeric protein of molecular mass 20 000.