Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: KEGG:D00046 (lactose)
16,692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Streptococcus lactis strain DR1251 was capable of growth on lactose and galactose with generation times, at 30 degrees C, of 42 and 52 min, respectively. Phosphoenolpyruvate-dependent phosphotransferase activity for lactose and galactose was induced during growth on either substrate. This activity had an apparent K(m) of 5 x 10(-5) M for lactose and 2 x 10(-2) M for galactose. beta-d-Phosphogalactoside galactohydrolase activity was synthesized constitutively by these cells. Strain DR1251 lost the ability to grow on lactose at a high frequency when incubated at 37 degrees C with glucose as the growth substrate. Loss of ability to metabolize lactose was accompanied by the loss of a 32-megadalton plasmid, pDR(1), and Lac(-) isolates did not revert to a Lac(+) phenotype. Lac(-) strains were able to grow on galactose but with a longer generation time. Galactose-grown Lac(-) strains were deficient in beta-d-phosphogalactoside galactohydrolase activity and phosphoenolpyruvate phosphotransferase activity for both lactose and galactose. There was also a shift from a predominantly homolactic to a heterolactic fermentation and a fivefold increase in galactokinase activity, relative to the Lac(+) parent strain grown on galactose. These results suggest that S. lactis strain DR1251 metabolizes galactose primarily via the tagatose-6-phosphate pathway, using a lactose phosphoenolpyruvate phosphotransferase activity to transport this substrate into the cell. Lac(-) derivatives of strain DR1251, deficient in the lactose phosphoenolpyruvate phosphotransferase activity, appeared to utilize galactose via the Leloir pathway.
...
PMID:Influence of the lactose plasmid on the metabolism of galactose by Streptococcus lactis. 10 44

Growth of galactose-adapted cells of Streptococcus lactis ML(3) in a medium containing a mixture of glucose, galactose, and lactose was characterized initially by the simultaneous metabolism of glucose and lactose. Galactose was not significantly utilized until the latter sugars had been exhausted from the medium. The addition of glucose or lactose to a culture of S. lactis ML(3) growing exponentially on galactose caused immediate inhibition of galactose utilization and an increase in growth rate, concomitant with the preferential metabolism of the added sugar. Under nongrowing conditions, cells of S. lactis ML(3) grown previously on galactose metabolized the three separate sugars equally rapidly. However, cells suspended in buffer containing a mixture of glucose plus galactose or lactose plus galactose again consumed glucose or lactose preferentially. The rate of galactose metabolism was reduced by approximately 95% in the presence of the inhibitory sugar, but the maximum rate of metabolism was resumed upon exhaustion of glucose or lactose from the system. When presented with a mixture of glucose and lactose, the resting cells metabolized both sugars simultaneously. Lactose, glucose, and a non-metabolizable glucose analog (2-deoxy-d-glucose) prevented the phosphoenolpyruvate-dependent uptake of thiomethyl-beta-d-galactopyranoside (TMG), but the accumulation of TMG, like galactose metabolism, commenced immediately upon exhaustion of the metabolizable sugars from the medium. Growth of galactose-adapted cells of the lactose-defective variant S. lactis 7962 in the triple-sugar medium was characterized by the sequential metabolism of glucose, galactose, and lactose. Growth of S. lactis ML(3) and 7962 in the triple-sugar medium occurred without apparent diauxie, and for each strain the patterns of sequential sugar metabolism under growing and nongrowing conditions were identical. Fine control of the activities of preexisting enzyme systems by catabolite inhibition may afford a satisfactory explanation for the observed sequential utilization of sugars by these two organisms.
...
PMID:Catabolite inhibition and sequential metabolism of sugars by Streptococcus lactis. 41 61

The effect of oral administration of galactose, lactose, and sucrose and intravenous injection of galactose on the urinary excretion of blood-group-active oligosaccharides has been studied. Galactose given either as the free sugar, a glycoside (lactose) or a constituent of normal diet was an absolute requirement for the formation and excretion of A-trisaccharide, B-trisaccharide and 2'-fucosylgalactose in blood group A, B and O(H) secretors, respectively. Great individual variation was seen in the amounts of galactose-dependent oligosaccharides excreted. Injection of galactose resulted in excretion of 3-59% of the amount of oligosaccharide formed after oral administration to the same individual. The mean ratio A-trisaccharide/B-trisaccharide was 2.7 in four blood-group-A1B secretors and 0.22 in three A2B secretors and can thus serve as a parameter for chemical differentiation between the two blood groups. The excretion of larger blood-group-active oligosaccharides, including the A-pentasaccharide, the B-pentasaccharide and lactodifucotetraose, that are normal components in urine from, respectively, starved A, B, and H secretors, was about the same after oral administration of galactose or lactose. The B-trisaccharide was the only oligosaccharide detected in plasma after oral galactose administration to a blood-group-B secretor individual. The concentration was 0.38 mg/l of plasma.
...
PMID:Urinary excretion of oligosaccharides induced by galactose given orally or intravenously. 51 Feb 88

Galactose, lactose, N-acetylgalactosamine, N-acetylglucosamine and fibrinoglycopeptides were bound to lysozyme by different linkages. These glycosylated lysozymes were tested as N-acetylneuraminic acid acceptors using particular sialytransferase preparations from frog and bovine liver and from bovine and porcine submandibular glands. Desialylated fetuin served as reference compound. Galactose residues of desialo-fetuin and lysozyme-lactose are sialylated by all four sialytransferases tested, galactose bound to lysozyme via a phenylazo group is inactive with the enzyme from bovine submandibular gland, and galactose bound directly to lysozyme serves as substrate only for the frog liver sialytransferase. Lysozyme-phenylazo-N-acetylgalactosamine is active only with the sialytransferase from bovine sumbandibular gland. N-Acetylglucosamine derivatives of lysozyme are inactive with all sialytransferases tested. These observations are discussed in the light of the natural substrates for the sialytransferases investigated.
...
PMID:The specificity of sialytransferases using glycosylated lysozyme derivatives as substrates. 51 Oct 94

At least four strategies have been developed by bacteria for capturing carbohydrates. They are typified by the transport mechanisms for glycerol, glucose, lactose, and galactose in Escherichia coli. Glycerol enters the cell by facilitated diffusion catalyzed by specific membrane protein. Once inside the cell, the substrate is trapped by phosphorylation mediated by an adenosine triphosphate (ATP)-dependent kinase. glucose is phosphorylated in transit by a membrane-associated phosphoenolpyruvate phosphotransferase system (PTS). A specific component of this complex serves also for signal recognition to chemotaxis. Lactose is concentrated chemically unaltered by beta-galactoside permease driven by a proton motive force. Galactose is also pumped into the cell, but the process is energized by ATP or its equivalent. In addition, there is a periplasmic galactose-binding protein essential for both transport and chemotactic response. The relative functional merits of each kind of transport mechanism are discussed. Although many bacterial species possess both the concentrative mechanism and the PTS, some employ the former and others the latter for beta-galactoside utilization. The postulate that the PTS is more avid in scavenging while the concentrative permease system permits a broader range of substrate exploitation is supported by the growth responses of 12 bacterial strains to several beta-galactosides.
...
PMID:Selective advantages of various bacterial carbohydrate transport mechanisms. 82 May 74

Galactose oxidase (E.C. 1.1.3.9) was covalently immobilized to chemically modified porous silica particles by reaction of the native enzyme with pendant benzoyl azide groups on the carrier. The enzyme loading on the carrier was 100-150 units per milliliter. The immobilized enzyme was incorporated into a hardware assembly suitable for the determination of galactose or lactose concentrations in complex biological fluids. The prototype instrument as described is suitable for continuous, on-line monitoring or discrete sample analysis. Reaction conditions can be readily provided which maintain global first order kinetics within the reactor and strict linearity of the procedure over a wide range of sample concentrations. Auto-inactivation of the immobilized enzyme can be prevented by K3Fe(CN)6 and long-term reactor stability can be achieved by the periodic application of the reagent to the enzyme reactor in situ.
...
PMID:Galactose oxidase: applications of the covalently immobilized enzyme in a packed bed configuration. 103 60

The ability of the horse to digest and absorb soluble carbohydrates was assessed using a series of oral disaccharide tolerance tests followed in the same animals by tolerance tests with the constituent monosaccharides. In horses older than three years, lactose did not produce an increase in the plasma glucose levels but induced the passing of soft faeces, indicating that adult horses are lactose intolerant. Horses of all ages could absorb the glucose: galactose mixture without any change in the faeces. The tolerance is due to a failure to hydrolyse lactose and does not involve the monosaccharide transport systems. These findings correspond to the known development pattern of brush border lactase activity in the equine small intestine. Both sucrose and maltose were rapidly hydrolysed, the resulting tolerance curves closely approximating to those for the constituent monosaccharides. Galactose was absorbed at a similar rate to glucose, although a dose of 1g/kg was necessary to produce galactosaemia. An oral lactose tolerance test (1 g/kg as a 20 per cent solution) could be of clinical value to determine small intestinal mucosal damage in diarrhoeic foals when the continued ingestion of lactose might be detrimental.
...
PMID:Carbohydrate digestion and absorption studies in the horse. 111 66

A lectin was isolated from the crude extract prepared from the seeds of E. costaricensis. It was purified by gel filtration on Sephadex G-100 followed by DEAE-Sephadex A-50 chromatography. PAGE revealed only one protein band, while analytical isoelectric focusing revealed four bands. The protein is a dimer with M(r) 58kda not united by disulfide bridges. It is a glycoprotein with 6.5% of neutral sugars, stable at 70 degrees C and at a pH range between 2 to 10. The protein exhibited a non specific agglutination of human erythrocytes, nevertheless it differentiated between erythrocytes of animal origin, agglutinating those of rabbit and chicken and not those from horse, goat, sheep or rat. Galactose, N-acetyl-D-galactosamine, lactose and EDTA are inhibitors while Ca++ and Mn++ acted as activators of the agglutination. No change in the blood pressure was observed when the lectin was intravenously injected in rats.
...
PMID:[Isolation, purification and characterization of a lectin from the seed of Erythrina costaricensis (Leguminosae)]. 184 49

Lactate has been shown to be an important fuel for brain metabolism during early postnatal development (1). In an attempt to identify the source(s) of lactate in the postnatal rat, we have studied the in vitro catabolism of glucose, galactose, fructose, alanine, glycerol, and octanoate in liver and muscle minces prepared from suckling rat pups. Whereas galactose, fructose, and octanoate were found to be lactagenic (lactate generating) in liver, glucose was the sole lactate precursor in muscle. Galactose was most effective as a hepatic lactate source at 3 d of age. Thereafter, the production of lactate from galactose decreased to reach control levels by 15 d of age. In contrast, fructose or octanoate were lactagenic throughout development. Lactate formation from galactose was completely halted by iodoacetate, inhibited by high galactose concentrations, and suppressed by fasting. The absence of oxygen increased lactate production from either fructose or octanoate, but it did not affect lactagenesis from galactose. Muscle minces produced lactate from glucose in an age-dependent manner similar to the development pattern of lactate formation from galactose by liver. Because lactose-derived galactose is readily available during suckling, it is suggested that galactose-based hepatic lactagenesis serves a unique role in maintaining the supply of lactate during early postnatal development. This hepatic capability may augment glucose-based muscle lactate synthesis at a time when lactate is a major brain fuel.
...
PMID:Lactate genesis by rat liver and muscle during development. 195 16

Type-specific carbohydrate antigen of the serotype i "Streptococcus milleri" was extracted with trichloroacetic acid from purified cell walls of the type strain K39K. The extracts were then purified by chromatography on DEAE-Sephadex A-25 and Sephadex G-100 columns. The purified serotype i carbohydrate antigen produced a single precipitin band against its homologous type-specific antiserum, which fused with the band produced by the autoclaved extract of the type strain cells. The serotype i antigen was a polysaccharide composed of rhamnose, galactose and glucose in a molar ratio of 1.6:6.8:1.0. The quantitative precipitin inhibition test with various haptenic sugars showed that galactose as well as lactose produced the greatest inhibition, which suggested that a galactose in terminal beta linkage is the immunodeterminant of the serotype i-specific antigen. Galactose was detected in the autoclaved extracts from cells of all the 15 serotype i strains tested.
...
PMID:Immunochemical characterization of type i carbohydrate antigen of "Streptococcus milleri" (Streptococcus anginosus). 212 90


1 2 3 4 5 6 7 8 9 10 Next >>

---