Nada Majkić-Singh

Spectrophotometric assay of xanthine oxidase with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulphonate) (ABTS) as chromogen

A new method for the determination of xanthine oxidase activity, based on the oxidation of 2,2-azino-di(3-ethylbenzthiazoline-6-sulphonate) (ABTS) by use of uricase and peroxidase, is described. The absorbance increase of the oxidized form of ABTS, measured after 10 min at 410 nm is proportional to xanthine oxidase activity. The method is sensitive, precise (CV below 8.3%), and linear up to 20 U/l. The analytical recovery of the ABTS-method was quantitative. Comparison with the UV and colorimetric NBT-method gave good correlation (r greater than or equal to 0.984). Reference values for serum xanthine oxidase activities determined with the new ABTS-method on 83 healthy persons are 0 to 1.20 U/l.

Esterase D polymorphism in Serbia (Yugoslavia)

Phenotypes of human red cell esterase D (EsD) were determined in 351 unrelated adults from Serbia (Yugoslavia). The calculated allele frequencies were 0.911 for EsD1 and 0.089 for EsD2. The phenotype distribution was in good agreement with the Hardy-Weinberg equilibrium.

Spectrophotometric determination of ethanol by an enzymatic method with 2, 2'-azino-di(3-ethylbenzthiazo- line-6-sulfonate)

Abstract The method is based on the oxidation of ethanol in the presence of alcohol oxidase, followed by oxidation of 2,2-azino-di(3-ethylbenzthiazoline-6-sulfonate) in the presence of peroxidase.

Evaluation of the Enzymatic Assay of Serum Uric Acid with 2,2′-Azino-Di(3-Ethylbenzthiazoline-6-Sulphonate) (ABTS) as Chromogen

A spectrophotometric method for the determination of serum uric acid based on the oxidation of 2,2′-azino-di(3-ethylbenzthiazoline-6-sulphonate) by use of uricase and peroxidase has already been reported. The method is very precise (CV <4·7%). The standard curve is linear up to 4640 μmol/L. Comparison with other enzymatic methods gave good correlation. The method gave results 9% lower than the phosphotungstate method. The effects of bilirubin, haemoglobin, glucose, ascorbic acid, anticoagulants and purine compounds were studied. The reference values for this method are 140·8–407·8 μmol/L for female subjects and 145·6–514·7 μmol/L for male subjects.

Determination of diamine oxidase by a kinetic method with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonate)

Abstract Hydrogen peroxide, the product of diamine oxidase-catalyzed putrescine or cadaverine oxidation, formed in proportion to the enzyme activity, is measured spectrophotometrically by using the above sulfonate (ABTS) and peroxidase. Only one reagent solution containing 3 mmol of putrescine or 10 mmol of cadaverine, 4 mmol of ABTS and 3000 U of peroxidase per litre of 0.2 mol l -1 Tris—0.1 mol l -1 HCl buffer pH 7.5 is needed. Absorbance changes are measured at 410 nm over the first 3 min of the reaction. This initial oxidation rate of the chromogen enables diamine oxidase activity up to 230 U l -1 to be determined.

Polymorphism of Human Red Cell Galactose-1-Phosphate Uridyl Transferase in Serbia, Yugoslavia

Phenotypes of human red cell galactose-1-phosphate uridyl transferase (GALT) were determined in 283 unrelated adults from Serbia (Yugoslavia). The gene frequencies were 0.959 for GALT N, 0.018 for GALT D and 0.023 for GALT N.

Activity of arylamidase in serum during normal pregnancy

SummaryReference values for the activity of arylamidase have been determined in sera of 371 women during normal pregnancy. An exponential relationship was found between enzyme activity and gestational age.

Determination of free and esterified cholesterol by a kinetic method. II. Evaluation of the enzymic method which uses 2,2-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) as chromogen.

A simple kinetic method for the determination of free and esterified serum cholesterol based on the oxidation of 2,2-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) by use of choilesterol esterase, cholesterol oxidase and peroxidase has already been reported. Here the method is statistically examined. The method is very sensitive and precise (C.V. below 5%). The standard curve is linear up to 25.9 mmol/l. Comparison with results by Abells method gave a linear regression of Yx = 0.2025 + 1.0043X with a correlation coefficient (r) of 0.983. Comparison with the enzymic methods of Roeschlau et al., Trinder, and Allain et al. gave Yx = 0.2037 + 0.9549X (r = 0.975), Yx = 0.4777 +0.8857X (r = 0.958) and Yx = 0.244 + 0.932X (r = 0.970), respectively. The effects of haemoglobin and bilirubin were studied and normal ranges for the method were determined on 150 healthy mature subjects of both sexes between 20 and 45 years of age. They are 3.375 to 6.948 mmol/l for total cholesterol, and 0.7196 to 2.089 mmol/l for free cholesterol.

Polymorphism of Red Cell Glyoxalase I in Serbia, Yugoslavia

Red cell glyoxalase I (GLO) phenotypes were determined in 258 unrelated adults from the population of Serbia (Yugoslavia). The GLO1 gene frequency was estimated to be 0.384.

Human Red Cell Adenylate Kinase Polymorphism in Srbija, Yugoslavia

Red cell adenylate kinase (AK) phenotypes were determined in 283 unrelated adults in Srbija (Yugoslavia). The gene frequencies observed were: AK1 0.961 and AK2 0.039. The adenylate kinase activity was estimated in all haemolysates; no significant differences were found between individuals of different phenotypes.