Disease relevance of D-Tagatose

• Molecular cloning, characterization, and nucleotide sequence of the tagatose 6-phosphate pathway gene cluster of the lactose operon of Lactococcus lactis [1].
• Crystal structure of Escherichia coli L-arabinose isomerase (ECAI), the putative target of biological tagatose production [2].
• Streptococcus mutans serotype c tagatose 6-phosphate pathway gene cluster [3].
• These values correspond to those reported previously for the tagatose pathway enzymes in Staphylococcus aureus and Lactococcus lactis [3].
• Tagatose and milk allergy [4].

High impact information on D-Tagatose

• Because we could not attribute fructose cytoprotection to metabolic effects, alterations in the expression of bcl-2, or metal chelation, we next determined if the poorly metabolized ketohexoses, tagatose and sorbose, also inhibited apoptosis; unexpectedly, both ketohexoses inhibited apoptosis [5].
• After the addition of 5 mM fructose, xylitol, tagatose, or D-xylulose, PRPP increased from a basal value of 6 +/- 1 nmol/g of cells to, respectively, 68 +/- 11, 42 +/- 11, 67 +/- 22, and 530 +/- 50 nmol/g of cells (means +/- SEM of 3-9 experiments) [6].
• In addition, the study shows that certain sugars such as glucose or tagatose, when added to redox-inactive glassy matrices, can be used as a source of thermal electrons that can be harvested by suitable redox active proteins, raising the prospect of using common sugars as an electron source in solid state thermal fuel cells [7].
• The tagatose 6-phosphate pathway gene cluster (lacABCD) encoding galactose-6-phosphate isomerase, tagatose-6-phosphate kinase, and tagatose-1,6-diphosphate aldolase of Lactococcus lactis subsp. lactis MG1820 has been characterized by cloning, nucleotide sequence analysis, and enzyme assays [1].
• Transcription studies showed that the four tagatose 6-phosphate pathway genes are the first genes of the lactose-inducible lactose-phosphotransferase operon consisting of the lacABCDFEGX genes [1].

Chemical compound and disease context of D-Tagatose

• The enzyme extract of E. coli with the plasmid pTC101 also converted galactose into tagatose with a 96.4% yield [8].

Biological context of D-Tagatose

• Analysis of the tagatose proteins expressed by recombinant plasmids in minicells was used to determine the sizes of the various gene products [3].
• Nucleotide and deduced amino acid sequences of the lacR, lacABCD, and lacFE genes encoding the repressor, tagatose 6-phosphate gene cluster, and sugar-specific phosphotransferase system components of the lactose operon of Streptococcus mutans [9].
• Pathway of gluconeogenesis from tagatose in rat hepatocytes [10].
• Sorbitol and tagatose were as potent as fructose in stimulating the phosphorylation of 5 mM glucose [11].
• Hydrolysis of lactose before thermal treatments promoted elevated accumulation of reducing sugars (galactose and glucose) that could be partially converted to the corresponding isomers (tagatose and fructose) during heating [12].

Anatomical context of D-Tagatose

• When incubated with tagatose, the hepatocytes accumulated tagatose 1-phosphate, a presumed inhibitor of phosphorylase a [13].
• Under the optimum conditions, the immobilized cell reactor with Mn2+ produced an average of 59 g/L tagatose with a productivity of 2.9 g/L.h and a conversion yield of 19.5% for the first 20 days [14].

Associations of D-Tagatose with other chemical compounds

• Further, the crystal structure of ECAI forms a basis for identifying molecular determinants responsible for isomerization of arabinose to ribulose in vivo and galactose to tagatose in vitro [2].
• Mutation of the lacA gene of the tagatose pathway caused impaired growth in lactose and galactose, suggesting that galactose can only be efficiently utilized when both the Leloir and tagatose pathways are functional [15].
• There was great phenotypic heterogeneity (13 different biotypes) based on the acidification of saccharose, tagatose, mannitol, and cyclodextrin and the presence of the enzymes pyroglutamic acid arylamidase and N-acetyl-beta-glucosaminidase [16].
• One hundred strains from 100 dairy herds in Denmark, 29 strains from 29 dairy herds in Pennsylvania, USA, 7 reference strains and 18 strains consisting of 9 paired strains from 9 quarters were investigated using biotyping (utilization of tagatose and sorbitol) and HindIII ribotyping [17].

Gene context of D-Tagatose

• Detection of tagatose 1,6-bisphosphate aldolase activity was dependent on expression of the 36-kDa protein specified by lacD [18].
• Differential display PCR demonstrated that the inactivation of S. gordonii luxS downregulated the expression of a number of genes, including gtfG, encoding glucosyltransferase; fruA, encoding extracellular exo-beta-D-fructosidase; and lacD encoding tagatose 1,6-diphosphate aldolase [19].
• In a separate study to characterize the molecular basis of aldolase specificity, the agaY-encoded tagatose 1,6-bisphosphate aldolase of E. coli was cloned, expressed and kinetically characterized [20].
• The S. mutans lacE and lacG genes are located in the same operon as the tagatose genes [21].
• Genes for the lactose-specific PEP-PTS proteins, phospho-beta-galactosidase and tagatose 6-phosphate pathway enzymes are encoded by a single 8 kb operon, lacABCDFEGX, and there is a divergently transcribed lacR repressor gene [22].

Analytical, diagnostic and therapeutic context of D-Tagatose

• The bioreactor produced 230 g/L tagatose from 500 g/L galactose in continuous recycling mode, with a productivity of 9.6 g/(L.h) and a conversion yield of 46% [23].
• Immobilized cells produced the highest tagatose concentration, indicating that cell immobilization was more efficient for tagatose production than enzyme immobilization [14].
• Small phase 2 clinical trials showed tagatose to be effective in treating type 2 diabetes [24].
• Drug evaluation: tagatose in the treatment of type 2 diabetes and obesity [25].

References