Showing papers on "Melibiose published in 1968"

Biochemical Studies on Lipopolysaccharides of Salmonella R Mutants

Abstract: In an in vitro system, containing 20,000 ×g cell wall particles and 100,000 ×g cell sap supernatant of various Salmonella rough mutants the rate of galactose transfer from UDP-[14C]-galactose to the core lipopolysaccharide was studied and the following results obtained: 1 Cell wall partieles from the S. minnesota mutants mR5, mR7, and mR8 are poor acceptors for galactose. The lipopolysaccharides of these mutants contain heptose and phosphate in a molar ratio of 2:2, whereas in normal lipopolysaccharide of Salmonella the ratio is 2:3. 2 20,000 ×g cell wall fractions from mutants which produce lipopolysaccharide of normal phosphate content, such as those from S. minnesota mRz or S. typhimurium tmM are good acceptors for galactose. 3 Phosphate-poor cell wall particles can be treated with ATP and enzyme extracts of mutants containing lipopolysaccharide of normal phosphate content to yield proper acceptors for galactose. 4 A radioactive disaccharide which chromatographically behaves like melibiose, and which after treatment with α-galactosidase yields [14C]galactose can be isolated from partial hydrolysates of cell wall particles which have previously been incubated with UDP-[14C]galactose and enzyme extract from tmM. This result is the same whether phosphate is already present in the cell wall fraction or is introduced enzymatically by the addition of ATP to the incubation mixture. It is concluded that mR5 and mR8 are defective in a lipopolysaccharide phosphorylating enzyme and that lack of phosphate groups in the lipopolysaccharide results in an incomplete core because unphosphorylated lipopolysaccharide acts only as a poor acceptor in the galactose transfer reaction.

Analysis of Melibiose Mutants Deficient in α-Galactosidase and Thiomethylgalactoside Permease II in Escherichia coli K-12

Abstract: Three types of mutants (mel−) unable to metabolize the α-d-galactoside, melibiose, were derived from Escherichia coli K-12. One type lacked α-galactosidase; another lacked a specific transport system, termed thiomethylgalactoside (TMG) permease II; and the third lacked both of these functions. The mutational sites were genetically mapped by recombination frequency with different markers and by determination of chromosomal transfer in interrupted-mating experiments. All three mel− mutant types mapped in a cluster near to the metA marker on the E. coli chromosome and were cotransducible. Induction studies revealed that the three α-d-galactosides, melibiose, melibiitol, and galactinol, induced α-galactosidase and TMG permease II coordinately; d-galactose also induced them but only in a galactokinaseless mutant. These data suggest that α-galactosidase and TMG permease II may be components of a common operon.

Myo‐Inositol, a Cofactor in the Biosynthesis of Stachyose

Abstract: 1 In extracts from Phaseolvs vulgaris seeds an enzyme has been found which transfers the galactosyl moiety of galactinol to raffinose giving rise to stachyose and myo-inositol. 2 Two tests to measure the enzyme activity are described. 3 The reaction is reversible. An equilibrium constant of approximately 4 has been determined for . The enzyme catalyzes exchange reactions between galactinol and myo-[14C]inositol and between stachyose and [14C]raffinose. Specifically labeled galactinol and stachyose can be prepared in this way. 4 The Km values for galactinol and for the two best galactosyl acceptors, raffinose and melibiose, have been measured. 5 Besides the galactinol: raffinose-6-galactosyl transferase the extract of the seeds also contains an α-galactosidase, which separates from the transferase during the purification. The transferase is strongly inhibited by p-chloromercuribenzoate. 6 Ripening seeds contain an enzyme which catalyzes the reaction UDP-galactose + myoinositol galactinol + UDP. However, no direct transfer of galactose from UDP-galactose to raffinose has been observed. 7 The physiological importance of the results is discussed.

Streptococcus faecium var. casseliflavus, nov. var

Abstract: Streptococcus faecium var. casseliflavus is a gram-positive, spherical cell. The cells occur chiefly as pairs within chains and elongate to ogive-shaped cells during growth. Growth is good on 5% bile salts-agar and in broth at 10 C, and in broth adjusted to pH 9.6 or containing 6.5% NaCl, but many strains fail to grow at 45 C. Litmus is reduced rapidly prior to formation of an acid curd. Few strains release ammonia from arginine or serine. The organism is not proteolytic and does not produce H(2)S or acetylmethylcarbinol, reduce nitrate, decarboxylate tyrosine, or produce slime on sucrose-agar. Most strains survive heating to 60 C for 30 min. It produces gray colonies on potassium tellurite agar, reduces 2,3,5-triphenyltetrazolium-HCl to a pink color, and ferments cellobiose, dextrin, maltose, mannose, and sorbitol, thus resembling S. faecalis. Like S. faecium, it produces peroxidase but not catalase on heated blood media, dissimilates malate, and ferments arabinose, melibiose, and salicin, but not melezitose. Like both species, it ferments dextrose, galactose, lactose, mannitol, sucrose, trehalose, and citrate. Properties peculiar to the variant include the high pH limiting initiation and termination of growth; the fermentation of alpha-methyl-d-glucoside, raffinose, and xylose; motility; and growth without blue button formation in ethyl violet broth. The water-soluble, pale lemon-yellow pigment is released into the aqueous phase only after the cell envelope is altered by fat solvents. The bacterium thrives as an epiphyte on plants.

Automated Carbohydrate Analysis of Physiologic Fluids

Abstract: Automated carbohydrate analysis can be useful clinically in the research laboratory as an aid in understanding the fundamental role of carbohydrates in metabolism, including their pathologic significance. An analytic system being developed at our laboratory utilizes an automated carbohydrate analyzer to chromatograph borated physiologic fluids while using strongly basic anion-exchange resin. The eluted carbohydrates are detected by sulfuric acid-phenol colorimetry. The carbohydrate analyzer used in this experimental work should become a useful tool in the clinical laboratory. Normal and diabetic human urine and blood serum have been chromatographed and significant differences established. As many as 38 peaks have been observed in the complex urine chromatograms. Using cochromatographic technics, 14 peaks have been tentatively identified as sucrose, raffinose, N-acetylglucosamine, maltose, lactose, ribose, fructose, arabinose, fucose, galactose, xylose, mannoheptulose, glucose, and glucose-1-phosphate. All except fucose have been quantified. Blood serum chromatograms consist of a major glucose peak and several smaller peaks indicating traces of other sugars. Melibiose has been used as an internal standard in chromatograms to determine recovery, resolution, and reproducibility. With the present technic, the lower limit of detectable sugar in physiologic fluids is in the 1-µg. range.

Variation in the fermentative pattern of some Saccharomyces species.

Abstract: The acquisition of the ability to ferment galactose, maltose, sucrose, raffinose and melibiose by yeast strains of the genus Saccharomyces was investigated During cultivation in selective media 11 strains belonging to 5 species gained the ability to ferment one or several of these sugars De-adaptation was not usually observed after cultivation in glucose medium, indicating that the saltants are stable in this medium

Galactosidase Activity of Lactose-positive Neisseria

Abstract: The chromogenic substrate o-nitrophenyl-beta-d-galactopyranoside (ONPG) was hydrolyzed by lactose-positive Neisseria. Eight strains of pharyngeal origin were examined. In culture reactions, seven strains resembled Neisseria meningitidis with the exception that they produced acid from 1% (w/v) lactose. An eighth strain (V8) differed in that it did not form acid from maltose or from 1% lactose. However, acid formation was observed in 10% lactose cultures of strain V8, suggesting that entry of lactose occurred by passive diffusion, rather than as a result of permease activity. The enzymes which hydrolyzed ONPG were produced constitutively by the cells of all eight strains. Thus, specific activity in these strains was not increased by prior exposure to lactose, or to two other possible inducers, isopropyl-beta-d-thiogalactoside or methyl-beta-d-thiogalactoside. Study of cell-free extracts of one strain showed that the enzyme was heat-labile, having a half-life of 10 min at 45 C. The enzyme was unstable at low protein concentrations, but it was protected completely or partially when albumin or manganous ions were added. The enzyme appeared to be a typical beta-galactosidase: alpha-galactosides (melibiose and p-nitrophenyl-alpha-d-galactopyranoside) were not hydrolyzed, activity against ONPG was not dependent upon inorganic phosphate, and galactose was released by cleavage of ONPG. ONPG hydrolysis provided a simple and rapid method for detecting lactose-positive Neisseria.

Candida friedrichii sp. n., a melibiose-fermenting yeast

Abstract: A new yeast that ferments raffinose and galactose and is unable of fermenting sucrose is described asCandida friedrichii. Four types of melibiose-fermenting yeasts are distinguished and discussed.

Galactosidase Activity ofLactose-positive Neisseria'

Abstract: (ONPG)was hydrolyzed bylactose-positive Neisseria. Eight strains ofpharyngeal origin were examined. Inculture reactions, sevenstrains resembled Neisseria meningitidis with theexception thattheyproduced acidfrom1% (w/v) lactose. An eighth strain (V8)differed inthatitdidnotformacidfrommaltose orfrom1% lactose. However,acidformation was observed in10%lactose cultures ofstrain V8,suggesting thatentryoflactose occurred bypassive diffusion, rather thanas a result of permeaseactivity. Theenzymeswhichhydrolyzed ONPG wereproduced constitutively bythecells ofalleight strains. Thus, specific activity inthese strains wasnotincreased byprior exposuretolactose, ortotwootherpossible inducers, isopropyl-:D-thiogalactoside ormethyl-3-D-thiogalactoside. Studyofcell-free extracts ofone strain showed that theenzymewasheat-labile, having a half-life of10minat45C. Theenzymewas unstable atlowprotein concentrations, butitwas protected completely orpartially whenalbumin ormanganousions wereadded. Theenzymeappeared tobeatypical 3-galactosidase: a-galactosides (melibiose andp-nitrophenyla-D-galactopyranoside) werenothydrolyzed, activity against ONPG was notdependent upon inorganic phosphate, andgalactose was released bycleavage of ONPG.ONPG hydrolysis provided a simple andrapid methodfordetecting lactose-positive Neisseria. Thecommonspecies ofNeisseria donottypically formacidfromlactose (Bergey's Manual). Nevertheless, lactose-positive strains havebeen described (13,15,16)whichbearconsiderable resemblance toNeisseria meningitidis. Asabasis forprojected genetic andtaxonomic studies of representative strains, theenzymatic action of these lactose-positive Neisseria onvarious galactosides wasexamined. Useofa chromogenic substrate, whichhasbeeninvaluable innumerous genetic investigations oflactose metabolism (1, 12), provided asensitive method fordetermining (3-galactosidase activity.