Phosphoric acid esters of galactose.

Growth-phase regulation of the Escherichia coli thioredoxin gene. (1/53)

The two promoters of Escherichia coli trxA gene were separately cloned into pKO100 as well as pJEL170. Galactokinase expression in cells containing the pKO100 derivatives was found to be negatively correlated with growth rate and was 6- to 20-fold higher in stationary cultures than in exponential cultures. The expression of trxA-galK was induced by amino acid starvation in a RelA(+) strain but not in an isogenic Rel(-) strain indicating that the control involves guanosine 3',5'-bispyrophosphate (ppGpp). RpoS, which appears to be essential for expression of most stationary phase expressed genes, is not required for trxA expression. Increased expression of relA, which increases ppGpp concentration, increases trxA expression.  (+info)

Engineering the active center of the 6-phospho-beta-galactosidase from Lactococcus lactis. (2/53)

Several amino acids in the active center of the 6-phospho-beta-galactosidase from Lactococcus lactis were replaced by the corresponding residues in homologous enzymes of glycosidase family 1 with different specificities. Three mutants, W429A, K435V/Y437F and S428D/ K435V/Y437F, were constructed. W429A was found to have an improved specificity for glucosides compared with the wild-type, consistent with the theory that the amino acid at this position is relevant for the distinction between galactosides and glucosides. The k(cat)/K(m) for o-nitrophenyl-beta-D-glucose-6-phosphate is 8-fold higher than for o-nitrophenyl-beta-D-galactose-6-phosphate which is the preferred substrate of the wild-type enzyme. This suggests that new hydrogen bonds are formed in the mutant between the active site residues, presumably Gln19 or Trp421 and the C-4 hydroxyl group. The two other mutants with the exchanges in the phosphate-binding loop were tested for their ability to bind phosphorylated substrates. The triple mutant is inactive. The double mutant has a dramatically decreased ability to bind o-nitrophenyl-beta-D-galactose-6-phosphate whereas the interaction with o-nitrophenyl-beta-D-galactose is barely altered. This result shows that the 6-phospho-beta-galactosidase and the related cyanogenic beta-glucosidase from Trifolium repens have different recognition mechanisms for substrates although the structures of the active sites are highly conserved.  (+info)

Lactose metabolism involving phospho-beta-galactosidase in Klebsiella. (3/53)

Klebsiella strain RE1755A is a Lac- Gal- mutant which has lost both of its lac operons, but possesses a gene specifying beta-galactosidase III, an enzyme which hydrolyzes o-nitrophenyl-beta-D-galactopyranoside but does not hydrolyze lactose. Selective pressure was applied to isolate mutants able to utilize lactose. The lactose-utilizing mutants obtained were shown to possess an unaltered beta-galactosidase III. Lactose utilization was shown to result from a pleiotropic mutation which also (i) permits galactose utilization and (ii) prevents induction of beta-galactosidase III synthesis by lactose. Evidence is presented suggesting that a phospho-beta-galactosidase enzyme is involved in lactose metabolism.  (+info)

Integrated genomic and proteomic analyses of a systematically perturbed metabolic network. (4/53)

We demonstrate an integrated approach to build, test, and refine a model of a cellular pathway, in which perturbations to critical pathway components are analyzed using DNA microarrays, quantitative proteomics, and databases of known physical interactions. Using this approach, we identify 997 messenger RNAs responding to 20 systematic perturbations of the yeast galactose-utilization pathway, provide evidence that approximately 15 of 289 detected proteins are regulated posttranscriptionally, and identify explicit physical interactions governing the cellular response to each perturbation. We refine the model through further iterations of perturbation and global measurements, suggesting hypotheses about the regulation of galactose utilization and physical interactions between this and a variety of other metabolic pathways.  (+info)

Neonatal screening for galactosemia by quantitative analysis of hexose monophosphates using tandem mass spectrometry: a retrospective study. (5/53)

BACKGROUND: Classic galactosemia (OMIM 230400) is an inherited disorder in the metabolism of galactose caused by deficiency of the enzyme galactose 1-phosphate uridyl transferase (EC 2.7.7.12). Galactosemia leads to accumulation of galactose and galactose 1-phosphate (gal-1-P) in blood and tissues and, if untreated, produces neonatal death or severe mental retardation, cirrhosis of the liver, and cataracts. Hence, the disorder is included in many neonatal screening programs. METHODS: We retrospectively analyzed filter-paper blood samples obtained 4-8 days postpartum for routine neonatal screening from 12 galactosemia patients and 2055 random controls. Total hexose monophosphates (HMPs) were used as a marker of gal-1-P and were assayed by negative-ion mode electrospray tandem mass spectrometry (tandem MS) with settings biased toward gal-1-P detection. The predominant precursor/product ion pair m/z 259/79 was used to quantify total HMPs by external standardization. RESULTS: Linear calibration curves were obtained in the range 0-8 mmol/L gal-1-P. The detection limit was 0.1 mmol/L HMP, and total CVs ranged from 13% at the detection limit to <8% at >1 mmol/L HMP. The method was in agreement with an alkaline phosphatase-galactose dehydrogenase method. All samples from galactosemia patients contained increased HMP concentrations (range for patients, 2.6-5.2 mmol/L; range for reference group, <0.10-0.94 mmol/L). The diagnostic sensitivity and specificity were 100% at a cutoff of 1.2 mmol/L HMP. A Duarte/classic galactosemia compound heterozygous sample could be discriminated clearly from both patient and reference samples. CONCLUSION: Quantitative analysis of HMPs by tandem MS can be used in laboratory investigations of galactosemia.  (+info)

Lactose metabolism in Streptococcus lactis: phosphorylation of galactose and glucose moieties in vivo. (6/53)

Starved cells of Streptococcus lactis ML3 grown previously on lactose, galactose, or maltose were devoid of adenosine 5'-triphosphate contained only three glycolytic intermediates: 3-phosphoglycerate, 2-phosphoglycerate, and phosphoenolpyruvate (PEP). The three metabolites (total concentration, ca 40 mM) served as the intracellular PEP potential for sugar transport via PEP-dependent phosphotransferase systems. When accumulation of [14C]lactose by iodoacetate-inhibited starved cells was abolished within 1 s of commencement of transport, a phosphorylated disaccharide was identified by autoradiography. The compound was isolated by ion-exchange (borate) chromatography, and enzymatic analysis showed that the derivative was 6-phosphoryl-O-beta-D-galactopyranosyl (1 leads to 4')-alpha-D-glucopyranose (lactose 6-phosphate). After maximum lactose uptake (ca. 15 mM in 15 s) the cells were collected by membrane filtration and extracted with trichloroacetic acid. Neither free nor phosphorylated lactose was detected in cell extracts, but enzymatic analysis revealed high levels of galactose 6-phosphate and glucose 6-phosphate. The starved organisms rapidly accumulated glucose, 2-deoxy-D-glucose, methyl-beta-D-thiogalactopyranoside, and o-nitrophenyl-beta-D-galactopyranoside in phosphorylated form to intracellular concentrations of 32, 32, 42, and 38.5 mM, respectively. In contrast, maximum accumulation of lactose (ca. 15 mM) was only 40 to 50% that of the monosaccharides. From the stoichiometry of PEP-dependent lactose transport and the results of enzymatic analysis, it was concluded that (i) ca. 60% of the PEP potential was utilized via the lactose phosphotransferase system for phosphorylation of the galactosyl moiety of the disaccharide, and (ii) the residual potential (ca. 40%) was consumed during phosphorylation of the glucose moiety.  (+info)

Erythrocyte galactose 1-phosphate quantified by isotope-dilution gas chromatography-mass spectrometry. (7/53)

BACKGROUND: Measurements of alpha-D-galactose 1-phosphate (Gal-1-P) in erythrocytes are used to monitor the adequacy of dietary therapy in the treatment of galactosemia. We have devised a gas chromatography-mass spectrometry (GC/MS) isotope-dilution method for quantification of Gal-1-P. METHODS: We prepared trimethylsilyl (TMS) derivatives and used alpha-D-[2-(13)C]Gal-1-P as the internal standard for GC/MS. Results obtained with this method were compared with those determined by the established enzymatic method for samples from 23 healthy individuals (11 children and 12 adults), 9 suspected patients with galactosemia, 12 galactosemic patients on diet therapy, and 2 newly diagnosed toxic neonates. RESULTS: The method was linear up to 2.5 mmol/L with a lower limit of detection of 2.1 nmol (0.55 mg/L). Intra- and interassay imprecision (CVs) was 2.2-8.8%. In the 23 healthy individuals, values ranged from nondetectable to 9.2 micromol/L (2.4 mg/L of packed erythrocytes). Galactosemic patients on diet therapy had values of 10.9-45 mg/L of packed erythrocytes, whereas the newly identified patients had values of 166 and 373 mg/L. CONCLUSIONS: The GC/MS method is precise and useful over the wide range of concentrations needed to assess the galactose burden in patients with galactosemia.  (+info)

GALT deficiency causes UDP-hexose deficit in human galactosemic cells. (8/53)

Previously we reported that stable transfection of human UDP-glucose pyrophosphorylase (hUGP2) rescued galactose-1-phosphate uridyltransferase (GALT)-deficient yeast from "galactose toxicity." Here we test in human cell lines the hypothesis that galactose toxicity was caused by excess accumulation of galactose-1-phosphate (Gal-1-P), inhibition of hUGP2, and UDP-hexose deficiency. We found that SV40-transformed fibroblasts derived from a galactosemic patient accumulated Gal-1-P from 1.2+/-0.4 to 5.2+/-0.5 mM and stopped growing when transferred from 0.1% glucose to 0.1% galactose. Control fibroblasts accumulated little Gal-1-P and continued to grow. The GALT-deficient cells had 157+/-10 micromoles UDP-glucose/100 g protein and 25+/-5 micromoles UDP-galactose/100 g protein when grown in 0.1% glucose. The control cells had 236+/-25 micromoles UDP- glucose/100 g protein and 82+/-10 micromoles UDP-galactose/100 g protein when grown in identical medium. When we transfected the GALT-deficient cells with either the hUGP2 or GALT gene, their UDP-glucose content increased to 305+/-28 micromoles/100 g protein (hUGP2-transfected) and 210+/-13 micromoles/100 g protein (GALT-transfected), respectively. Similarly, UDP-galactose content increased to 75+/-12 micromoles/100 g protein (hUGP2-transfected) and 55+/-9 micromoles/100 g protein (GALT-transfected), respectively. Though the GALT-transfected cells grew in 0.1% galactose with little accumulation of Gal-1-P (0.2+/-0.02 mM), the hUGP2-transfected cells grew but accumulated some Gal-1-P (3.1+/-0.4 mM). We found that 2.5 mM Gal-1-P increased the apparent KM of purified hUGP2 for glucose-1-phosphate from 19.7 microM to 169 microM, without changes in apparent Vmax. The Ki of the reaction was 0.47 mM. Gal-1-P also inhibited UDP-N-acetylglucosamine pyrophosphorylase, which catalyzes the formation of UDP-N-acetylglucosamine. We conclude that intracellular concentrations of Gal-1-P found in classic galactosemia inhibit UDP-hexose pyrophosphorylases and reduce the intracellular concentrations of UDP-hexoses. Reduced Sambucus nigra agglutinin binding to glycoproteins isolated from cells with increased Gal-1-P is consistent with the resultant inhibition of glycoprotein glycosylation.  (+info)

I'm sorry for any confusion, but "galactosephosphates" is not a widely recognized or established term in medicine or biochemistry. It seems that this term may be a combination of "galactose," which is a simple sugar, and "phosphate," which is a common ion found in biological systems. However, without more context, it's difficult to provide an accurate medical definition for this term.

Galactose is a monosaccharide that is metabolized in the body through the Leloir pathway, and defects in this pathway can lead to genetic disorders such as galactosemia. Phosphates are often found in biological molecules, including nucleic acids (DNA and RNA) and certain sugars (like glucose-1-phosphate).

Without further context or information about how "galactosephosphates" is being used, I would be cautious about assuming that it refers to a specific medical concept or condition.

... galactosephosphates MeSH D09.894.417.448 - glucosephosphates MeSH D09.894.417.448.500 - glucose-6-phosphate MeSH D09.894. ...
... galactosephosphates MeSH D09.894.417.448 - glucosephosphates MeSH D09.894.417.448.500 - glucose-6-phosphate MeSH D09.894. ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
Newburger PE, Pagano JS, Greenberger JS, Karpas A, Cohen HJ. Dissociation of opsonized particle phagocytosis and respiratory burst activity in an Epstein-Barr virus-infected myeloid cell line. J Cell Biol. 1980 Jun; 85(3):549-57 ...
Galactosephosphates [D09.894.417.370] * Glucosephosphates [D09.894.417.448] * Hexosediphosphates [D09.894.417.592] * ...
Galactosephosphates / metabolism Actions. * Search in PubMed * Search in MeSH * Add to Search ...
Galactosephosphates Preferred Term Term UI T017214. Date01/01/1999. LexicalTag NON. ThesaurusID NLM (1978). ... Galactosephosphates Preferred Concept UI. M0008943. Registry Number. 0. Scope Note. Phosphoric acid esters of galactose.. Terms ... Galactosephosphates. Tree Number(s). D09.894.417.370. Unique ID. D005695. RDF Unique Identifier. http://id.nlm.nih.gov/mesh/ ...
Galactosephosphates Preferred Term Term UI T017214. Date01/01/1999. LexicalTag NON. ThesaurusID NLM (1978). ... Galactosephosphates Preferred Concept UI. M0008943. Registry Number. 0. Scope Note. Phosphoric acid esters of galactose.. Terms ... Galactosephosphates. Tree Number(s). D09.894.417.370. Unique ID. D005695. RDF Unique Identifier. http://id.nlm.nih.gov/mesh/ ...
Galactosephosphates Galactosidase use Galactosidases Galactosidase, Galactosylceramide use Galactosylceramidase Galactosidases ...
GALACTOSEPHOSPHATES] 79. ԳԱՄԲԻԱ [GAMBIA] 30. ԳԱԼԱԿՏՈԶԱՖՈՍՖԱՏՆԵՐ [GALACTOSEPHOSPHATES] 80. ԳԱՄԲԻԱ [GAMBIA] 31. ԳԱԼԱԿՏՈԶԵՄԻԱ [ ...
N0000007255 Galactose N0000167975 Galactose Dehydrogenases N0000167997 Galactose Oxidase N0000168552 Galactosephosphates ...
D9.546.359.377 Galactosephosphates D9.203.894.417.370 D9.894.417.370 Galactosides D9.203.408.320 D9.408.320 Galactosylceramides ...
galactosephosphates. Other Resources:. Words people are searching for today: moteliers, concierges, dicrotic_wave, creepingly, ...

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