A convenient method for the crystallization of sugars and other organic substances

Tauber, Henry; Kleiner, Israel S.

doi:10.1021/ed009p1970

Cited by 9 publications

(11 citation statements)

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“…However, in view of our experiments which show that maltase is digested and inactivated by trypsin, it is possible that the inactivation of yeast-maltase during autolysis really may have been due to the action of proteases, which are found in abundance in yeast, and which act best at a pH ranging between 4.0 to 7.8. Some enzymes (16) are not digested by trypsin, and crystalline ureaseisinactivatedby trypsin only if a gum is present (17,18). Sumner and Kirk (19) could not digest crystalline urease with trypsin, with or without gum, but Sumner, Kirk, and Howell (20) digested crystalline urease with pepsin and with papain.…”

Section: Discussionmentioning

confidence: 99%

The Digestion and Inactivation of Maltase by Trypsin and the Specificity of Maltases

Tauber

Kleiner

1933

Journal of General Physiology

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In 1925 Leibowitz (1) proposed the theory that there are two kinds of maltases,--one kind present in yeast, having the power of hydrolyzing maltose and a-methylglucoside and another found in moulds (2--4) with only maltose-splitting power. Thus he would differentiate between glucosidomaltase and glucomaltase. But Weidenhagen (5) has taken quite a different view. He thinks that sucrose may be hydrolyzed by a-glucosidase and by a/~-h-fructosidase, and maltose only by a-glucosidase. This he explains by his steric configurative theory, according to which one and the same enzyme, a-glucosidase, must be able to hydrolyze sucrose, maltose, and a-glucosides since each has an a-glucosido rest bound to a glycone or an aglycone. In other words this means that the classical nomenclature of maltase, sucrase, etc., would have to be dropped, since such separate enzymes would not exist. Recently we (6) have shown the maltase of the mammary gland to be unmistakably a glucomaltase, hydrolyzing maltose but not sucrose or a-methylglucoside, thus corroborating the theory of Leibowitz. Doubt has been cast upon Weidenhagen's work (7) from another angle by Karstroem (8), Myrbaeck (9), and Virtanen (10) who found that the enzyme of a certain strain of B. colt can hydrolyze maltose but not cane sugar. Experiments on moulds by Pringsheim, Borchard, and Loew (11) speak also against the theory of Weidenhagen.Since, in enzyme chemistry, the question whether there are distinct maltases and sucrases is of considerable importance, we have undertaken to procure additional data by studying the maltase of saliva and the maltase produced by Escherichia colt. For the determination of enzyme activity we have used an improved technic. We have utilized our new method (12) which permits of the determination of minute 767

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Section: Discussionmentioning

confidence: 99%

The Digestion and Inactivation of Maltase by Trypsin and the Specificity of Maltases

Tauber

Kleiner

1933

Journal of General Physiology

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“…The Si(IV)-Mo(VI) solution is initially yellowish due to the formation of yellow molybdosilicate anionic species, 2 and the monosaccharide reduces directly the Mo(VI) species to form a mixed-valence molybdosilicate anion, which renders the solution blue. This method is simple and easy to carry out in comparison with the conventional reducing saccharide assay using a copper(II) reagent, such as the Somogyi-Nelson 3,4 and Tauber-Kleiner 5,6 methods. Also, even in a ketose assay, 7 our method shows higher reproducibility than the conventional method using a phenol-acetone-borate reagent.…”

Section: Introductionmentioning

confidence: 99%

Determination of Chitin Based on the Colorimetric Assay of Glucosamine in Acidic Hydrolysate

et al. 2016

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A colorimetric method for the glucosamine (GlcN) assay was applied for the determination of chitin, which can be hydrolyzed to produce GlcN. A 10-mg sample was mixed with 10 mL of a 5 mol/L HCl aqueous solution, and the mixture was kept at 100 C for 12 h. Under these conditions, chitin was completely depolymerized and deacetylated to produce GlcN, even when the sample was a crab shell. A 20-μL aliquot of the hydrolysate was mixed with 20 μL of a 5 mol/L NaOH aqueous solution and 200 μL of a 50 mmol/L Na2SiO3, 600 mmol/L Na2MoO4, 1.5 mol/L CH3COOH and 30% (v/v) dimethyl sulfoxide solution. The mixture was kept at 70 C for 30 min. In the mixture, GlcN reduced the Mo(VI) species to form a blue molybdosilicate anion, which gave an absorbance maximum at around 750 nm. Since N-acetylglucosamine and chitin oligosaccharides could not render the reaction mixture blue, GlcN in the hydrolysate could be assayed colorimetrically with high selectivity. When a standard chitin sample was examined, the GlcN concentration in the hydrolysate was determined to be 0.97 ± 0.02 g/L (as hydrochloride salt), indicating that the sample contained 10.0 ± 0.2 mg chitin (as an N-acetylglucosamine homopolymer). Calcium cation, amino acids, and proteins did not interfere with the GlcN assay. Thus, the proposed method was successfully applied to determine chitin in a crab shell sample.

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“…The method is simple and easy to carry out in comparison with the conventional colorimetric monosaccharide determination using a copper(II) reagent. 8,9 Since poly-and oligosaccharides would not interfere with the determination of monosaccharide at the same concentration level, the colorimetric method can be applied advantageously to a microtiter plate assay of saccharifying enzyme. Also, the method has been optimized for the determination of fructose in the presence of excess glucose, and has been successfully applied to the high-throughput screening of glucose isomerase.…”

Section: Introductionmentioning

confidence: 99%

Microplate Assay of α-Glucosidase and Its Inhibitors Based on the Direct Reduction of Molybdosilicate by Glucose

et al. 2015

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A colorimetric method for monosaccharide determination (Anal. Sci., 2013, 29, 1021 was optimized for the high-throughput screening of α-glucosidase, which hydrolyzes an α-1,4-glycosidic bond of starch and related oligo-and polysaccharides, followed by the release of D-glucose from the non-reducing ends. In a microplate, 40 μL of a sample solution was mixed with 160 μL of a 50 mM Na2SiO3, 600 mM Na2MoO4, 1.5 M CH3COOH, and 20% (v/v) dimethyl sulfoxide solution, which was yellowish due to the formation of a yellow molybdosilicate. The mixture was kept at 80 C for 60 min. In the mixture, glucose reduced the Mo(VI) species directly to form a blue heteropolymolybdate(V/VI). Thus, 0.1 mM level glucose can be determined by the color change from yellow to blue. Since maltose cannot render the mixture blue as strongly as glucose, the present method has been successfully applied to a microtiter plate assay of α-glucosidase with the disaccharide. Also, the method has been applied to an assay of α-glucosidase inhibitors, acarbose and quercetin.

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A convenient method for the crystallization of sugars and other organic substances

Cited by 9 publications

References 0 publications

The Digestion and Inactivation of Maltase by Trypsin and the Specificity of Maltases

The Digestion and Inactivation of Maltase by Trypsin and the Specificity of Maltases

Determination of Chitin Based on the Colorimetric Assay of Glucosamine in Acidic Hydrolysate

Microplate Assay of α-Glucosidase and Its Inhibitors Based on the Direct Reduction of Molybdosilicate by Glucose

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