scispace - formally typeset
Search or ask a question

Showing papers on "Melibiose published in 1970"


Journal ArticleDOI
TL;DR: The effects of pH, substrate concentration, inhibitors, and temperature on the catalytic activity of the crystalline enzyme are described.

94 citations


Journal ArticleDOI
TL;DR: Investigations by means of thin-layer chromatography indicated that the addition of small amounts of this enzyme preparation to soy milk resulted in complete hydrolysis of galacto-oligosaccharides.
Abstract: SUMMARY As part of a program to reduce the flatulence-inducing tendency of soy milk, a method for the enzymatic removal of galacto-oligosaccharides by means of an enzyme preparation from Aspergillus saitoi was investigated. It was found that a partially purified preparation possessing both α-galactosidase and invertase, yet free from protease, could be obtained easily from a commercial A. saitoi acid-protease product by means of a simple molecular sieving procedure. The α-galactosidase exhibited its optimum pH between 5.0 and 5.5, and seemed to be stable between pH 4.0 and 8.0. The optimum temperature was found at about 55°C; however, the enzyme itself was inactivated by maintaining it at 70°C for 30 min. These properties appeared suitable for the enzymatic treatment of soy milk. p-Chloromercuribenzoate, N-bromosuccinimide, HgCl2, AgNO3 or CuCl2 showed strong inhibitory effects on the enzyme. The presence of 1 x 10-2M galactose caused only slight inhibition. Km value of the enzyme with melibiose as a substrate was found to be 3.11 x 10-3M and the molecular weight of the enzyme estimated to be about 290,000 on the basis of a gel filtration technique. Investigations by means of thin-layer chromatography indicated that the addition of small amounts of this enzyme preparation to soy milk resulted in complete hydrolysis of galacto-oligosaccharides. The practicability of the present method was also discussed from an economic viewpoint.

92 citations



Journal ArticleDOI
TL;DR: The α-Galactosidase (α- d -galactoside galactohydrolase, EC 3.23) and β-galactosaidase were extracted from spinach leaves and separated from each other by chromatography on DEAE-cellulose and by Sephadex gel filtration.

41 citations


Journal ArticleDOI
TL;DR: D diets containing glucose, fructose, galactose, maltose, trehalose, melezitose, and sorbitol were also ingested optimally and well utilized and the four pentoses tested and mannose acted as feeding deterrents and their utilizability remained undecided.

28 citations


Journal ArticleDOI
TL;DR: Conidia of Penicillium griseofulvum Dierckx were found to have an absolute requirement for glucose to initiate germination, and spores did not swell or germinate in the absence of glucose, although they were shown to be permeable to water.
Abstract: Conidia of Penicillium griseofulvum Dierckx were found to have an absolute requirement for glucose to initiate germination. Spores did not swell or germinate in the absence of glucose, although they were shown to be permeable to water. Maximum germination required the presence of nitrate and phosphate in addition to glucose. Rate of germination was dependent on glucose concentration in the early stages but later stages of the germination process were independent of the glucose concentration over the range tested. Of other sugars tested, galactose and melibiose induced germination but were scarcely used for mycelial growth, whilst fructose and lactose were completely unable to induce germination but supported mycelial growth almost as vigorously as glucose. During germination in glucose medium spores rapidly increased their uptake of oxygen and lost their resistance to drying. In the absence of oxygen, or presence of cyanide, only partial swelling occurred and no germ tubes were formed. Germination was inhibited by high spore density, and by removal of carbon dioxide from the medium.

22 citations


Journal ArticleDOI
TL;DR: Lysosomes in homogenates of Tetrahymena pyriformis have been shown to be permeable to the cryoprotective nonelectrolytes glycerol and dimethylsulphoxide, to the hexoses glucose, galactose and α-methylglucose and to the hexitols mannitol, sorbitol and inositol.

15 citations


Journal ArticleDOI
TL;DR: The hydrolysis of p‐nitrophenyl‐α‐galactoside occurred optimally at pH 4·9, showed an approximate Km of 1·0 × 10−3m, and was markedly inhibited by melibiose, galactose and the mercuric ion.
Abstract: — The presence of α-galactosidase activity has been demonstrated in rat brain. This enzyme, located mainly in the crude mitochondrial fraction, actively hydrolysed the substrates p-nitrophenyl-α-galactoside and melibiose, and also catalysed the hydrolysis of digalactosyl diglyceride of both animal and plant origin. The hydrolysis of p-nitrophenyl-α-galactoside, as catalysed by the α-galactosidase, occurred optimally at pH 4·9, showed an approximate Km of 1·0 × 10−3m, and was markedly inhibited by melibiose, galactose and the mercuric ion.

15 citations


Journal ArticleDOI
TL;DR: In this article, the reaction of methanolic or aqueous ammonia with octa-O-acetyl-β-melibiose gives Nacetyl 6 O-α-D-galactopyranosyl, β-D -glucofuranosylamine (I) and 1,1-bis(acetamido)-1-deoxy-6 O-γα-d-glucitol (IV).
Abstract: The reaction of methanolic or aqueous ammonia with octa-O-acetyl-β-melibiose gives N-acetyl-6-O-α-D-galactopyranosyl-β-D-glucofuranosylamine (I) and 1,1-bis(acetamido)-1-deoxy-6-O-α-D-galactopyranosyl-D-glucitol (IV). The structure of the furanoid compound was demonstrated by oxidation with periodate. The factors which determine the different yields of these products in both media are discussed and the yields are compared with those of nitrogenated products obtained by ammonolysis of acetates of 1,4-linked disaccharides.

3 citations


Journal ArticleDOI
TL;DR: Sugars present in some Brazilian varieties of common beans were studied by two-dimension paper chromatography with the following pair of solvente: phenol-water-amonia and butanol-acetic acid-water.
Abstract: Sugars present in some Brazilian varieties of common beans (Phaseolus vulgaris L.) were studied by two-dimension paper chromatography with the following pair of solvente: 1) phenol-water-amonia, 80: 20: 0,5 (w/v/v/ and 2) butanol-acetic acid-water, 40: 10: 5 (v/v). Determinations were made by elution of the spots followed by colorimetry. The sugars identified and measured were raffinose, sucrose, melibiose, glucose and fructose. The more abundant sugars were fructose and glucose.

2 citations