PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “PHOSPHOTRANSFERASES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed1978

Studies on ATP: thiamine diphosphate phosphotransferase activity in rat brain.

The experiments described in this paper serve as a contribution to the solution of the discrepancies which exist in the assay of ATP:thiamine diphosphate phosphotransferase activity (EC 2.7.4.15), presently in use as a tool for the diagnosis of Leigh's disease (SNE, subacute necrotizing encephalomyelopathy). The results obtained with this phosphotransferase assay can, in part, be explained by the presence of thiamine triphosphate (ThTP) in the preparation of thiamine diphosphate (ThDP) used as a substrate, by the inhibition by ATP of the ThTP phosphohydrolase activity, present in fractions of rat brain homogenates, and by the stimulation by ThDP of the ATPase activity. When [2(-14)C-thiazole]thiamine was used for the synthesis of [14C]ThTP in fractions of rat brain, it was found that after chromatographic separation of thiamine and its phosphates, 14C radioactivity could be demonstrated in the ThTP fractions, even in the absence of an enzyme source. Probably a complex is formed between [14C]thiamine and a phosphate ester which behaves chromatographically as ThTP. It is concluded that the assay system for the measurement of ThTP synthesis in its present form is, in our hands, not suitable for diagnostic purposes.

Adenosine Triphosphate↗
PubMed1977

Effects of N2, O2'-dibutyril cyclic GMP on the nucleoside phosphotransferase activity of the retina of the chick embryos.

In the retina of the chick embryo, 2 different forms of nucleoside phosphotransferase take part in the phosphorylation of thymidine. One is an unstable form with higher molecular weight. The other with lower m. wt is a stable form. This paper shows that N2,O2'-dibutyril cyclic GMP causes a marked decrement of the activity of the unstable nucleoside phosphotransferase.

Animals↗
PubMed1990

Evolutionary origin of aminoglycoside phosphotransferase resistance genes.

The protein sequences of seven 3'-aminoglycoside phosphotransferases falling into the six identified types and three 6'-aminoglycoside phosphotransferases were analyzed to give a rooted phylogenetic tree. This tree supports the origin of these groups of enzymes in an ancestor closely related to the actinomycetes, and that horizontal transfer of the resistance genes occurred, possibly via transposons. The implications for genetic engineering of a novel antibiotic are discussed.

Actinomycetales↗
PubMed1976

Effect of ethanol ingestion on choline phosphotransferase and phosphatidyl ethanolamine methyltransferase activities in liver microsomes.

The effect of ethanol ingestion on choline phosphotransferase and phosphatidyl ethanolamine methyltransferase activities, the two enzymes involved in phosphatidyl choline biosynthesis in liver microsomes, has been investigated. Female rats were fed a 5% ethanol-liquid diet containing amino acids, minerals, vitamins, with and without choline, for 2, 6 and 10 weeks. Control animals were pair-fed the same isocaloric diet with 5% sucrose with and without choline. Ethanol administration with or without dietary choline stimulated significantly (P less than 0.001) the specific activities of phosphatidyl ethanolamine methyltransferase in liver microsomes in the animals fed 5% ethanol for 2, 6, and 10 weeks, when compared to those control animals pair-fed the isocaloric diet with or without choline. Ethanol administration with or without dietary choline for 2 weeks stimulated significantly (P less than 0.02) the specific activities of choline phosphotransferase. The specific activities of phosphatidyl ethanolamine methyltransferase continued to increase in the liver microsomes from the animals in which dietary choline was omitted for 2, 6, and 10 weeks in the sucrose controls and alcohol-fed animals. Ethanol administration stimulates significantly (P less than 0.001) the phosphatidyl ethanolamine methyltransferase specific activities in liver microsomes of animals fed the liquid diet with dietary omission of choline and methionine for 2 weeks.

Alcohol Drinking↗
PubMed1998

CRP down-regulates adenylate cyclase activity by reducing the level of phosphorylated IIA(Glc), the glucose-specific phosphotransferase protein, in Escherichia coli.

The cellular cAMP level is markedly down-regulated by cAMP receptor protein (CRP) in Escherichia coli. CRP regulates adenylate cyclase both at the level of transcription of its structural gene cya and at the level of enzyme activity. We established a method to determine the phosphorylation state of IIA(Glc), the glucose-specific phosphotransferase protein, in intact cells. We found that IIA(Glc) exists predominantly in the unphosphorylated form in wild-type cells growing in LB medium, while it is largely phosphorylated in crp or cya cells. Disruption of the ptsG gene that codes for the membrane component of the major glucose transporter (IICB(Glc)), and/or the fruF gene coding for FPr (fructose-specific hybrid phosphotransferase protein), did not affect the phosphorylation state of IIA(Glc). When IICB(Glc) was overproduced in the presence of glucose, the levels of both cAMP and phosphorylated IIA(Glc) in crp cells were concomitantly decreased to wild-type levels. In addition, when His-90 in IIA(Glc) was replaced by glutamine, both phosphorylation of IIA(Glc) and the overproduction of cAMP in crp cells were eliminated. We also found that extracts of crp+ cells markedly stimulate dephosphorylation of IIA(Glc)-P in vitro. We conclude that CRP-cAMP down-regulates adenylate cyclase primarily by reducing the level of phosphorylated IIA(Glc). The data suggest that unspecified proteins whose expression is under the control of CRP-cAMP are responsible for this regulation.

Adenylyl Cyclases↗
PubMed1985

Assay of aminoglycoside phosphotransferase in situ.

A method for the evaluation of the aminoglycoside phosphotransferase activity in bacterial colonies directly is described. The method is based on the ability of the enzyme to modify the substrate immobilized on carboxymethylcellulose paper. The sensitivity and accuracy of the method were tested by comparing the results of the present assay to those obtained with conventional procedures. The method seems to be particularly useful for the detection within a bacterial population producing aminoglycoside phosphotransferase of those cells which do not make the enzyme and for rapid determination of the relative levels of enzyme produced by different clones.

Cloning, Molecular↗
PubMed1983

Control of sugar utilization in the oral bacteria Streptococcus salivarius and Streptococcus sanguis by the phosphoenolpyruvate: glucose phosphotransferase system.

Three different Strep. salivarius (G2, G5 and G29) and two Strep. sanguis (GS3 and GS12) mutants affected in the phosphoenolpyruvate: glucose phosphotransferase system were selected on agar plates containing lactose and 2-deoxyglucose. All 5 were defective in a membrane-bound component of the transport system and grew less rapidly than the parent strain in 5 mM glucose-containing medium. Mutants G2 and G29 grew poorly in the presence of 5 mM mannose. Growth on mixed substrates revealed that the mutants and wild-type parents behaved differently. Wild-type strains in medium containing glucose plus another sugar (lactose, galactose, melibiose, raffinose or trehalose for Strep. salivarius and lactose, galactose or trehalose for Strep. sanguis) always exhausted most of the glucose before utilizing the other sugar. The mutants used the second sugar concurrently or preferentially to glucose. In medium containing glucose plus fructose or mannose, the wild types consumed both sugars concurrently whereas the mutants utilized the second sugar before glucose. Mutants G2 and G5 were insensitive to repression by fructose and released glucose into the medium when grown in the presence of 0.4 per cent lactose. Mutant G5 also released galactose. Sugar release was not detected with the wild types. The Strep. salivarius mutants contained normal levels of glucokinase and beta-galactosidase but G5 was almost totally devoid of galactokinase activity after growth on lactose. On galactose, the activity was restored. It seems that the phosphoenolpyruvate: glucose phosphotransferase system is involved in the regulation of sugar utilization in these two streptococci.

Glucose↗
PubMed1976

Effects of colicins K and E1 on the glucose phosphotransferase system.

1. Glycerol-grown cells of Escherichia coli and its mutant uncA, treated with colicin E1 or K, exhibited a several-fold higher level of alpha-methylglucoside uptake than untreated cells. This stimulation was independent of the carbon source present during the uptake test. In a mutant strain that has elevated levels of alpha-methylglucoside accumulation the addition of colicin E1 or carbonylcyanide m-chlorophenylhydrazone (CCCP) did not further enhance the uptake. 2. Colicins K and E1 decreased the apparent Km for alpha-methylglucoside uptake significantly and increased the V about twofold. The exit of the glucoside was severely inhibited by the colicins. 3. In the presence of colicins, alpha-methylglucoside is still accumulated via the phosphoenolpyruvate-phosphotransferase system since no accumulation or phosphorylation occurs in an enzyme I mutant. The colicins increased the relative intracellular concentration of phosphorylated alpha-methylglucoside, possibly by inhibiting the dephosphorylation reaction, and caused an excretion of this compound. 4. The results are interpreted as indicating that energization of the membrane has an inhibitory effect on the phosphotransferase system. Possible modes of action are discussed.

Biological Transport↗
PubMed1975

Mammalian carbamyl phosphate : glucose phosphotransferase and glucose-6-phosphate phosphohydrolase: extended tissue distribution.

Carbamyl phosphate : glucose phosphotransferase and glucose-6-phosphate (Glc-6-P) phosphohydrolase activities have beeh demonstrated in pancreas, adrenals, brain, testes, spleen, and lung. Catalysis of these activities by classical multifunctional glucose-6-phosphatase (D-glucose-6-phosphate phosphohydrolase; EC 3.1.3.9) has been firmly established for the first four of these tissues on the basis of characteristic catalytic properties of the transferase pH-activity profiles, apparent Km values for carbamyl phosphate and glucose, substrate specificity, susceptibility to inhibition by molybdate, and activation by deoxycholate. Additional such activity due to non-specific acid (and alkaline) phosphatase action also is indicated at very high glucose concentrations. The possible physiological significance of the newly-elucidated presence of glucose-6-phosphatase-phosphotransferase in these various tissues, in addition to previously extensively studied liver, kidney, and mucosa of small intestine, is discussed briefly.

Adrenal Glands↗
PubMed1979

Nucleoside phosphotransferase from yellow lupin seedling cotyledons.

Nucleoside phosphotransferase (nucleotide:3'-deoxynucleoside 5'-phosphotransferase, EC 2.7.1.77) from yellow lupin seedling cotyledons was purified and the active enzyme consists of a single polypeptide chain, Mr = 72 000 +/- 3000. In transphosphorylation, purine and pyrimidine nucleosides are good phosphate acceptors and 5'-nucleotides are effective phosphate donors. Among 2'- and 3'-nucleotides, only 3'-AMP and 3'-psi MP acted as phosphate donors, and p-nitrophenylphosphate appeared less active in this regard. The purine and pyrimidine bases inhibit transphosphorylation. The Km values determined for the inosine:5'-AMP pair were 400 micrometers for both the compounds. The enzyme showed optimum activity at pH 8.0 in mM Tris-HCl buffer. Antisulfhydryl reagents and EDTA did not affect enzyme activity.

Chemical Phenomena↗
PubMed1983

Fructose 2,6-bisphosphate as a contaminant of commercially obtained fructose 6-phosphate: effect on PPi:fructose 6-phosphate phosphotransferase.

Fructose 6-phosphate from several commercial sources was shown to be contaminated with fructose 2,6-bisphosphate. This contaminant was identified by its activation of PPi:fructose 6-phosphate phosphotransferase, extreme acid lability and behaviour on ion-exchange chromatography. The apparent kinetic properties of PPi:fructose 6-phosphate phosphotransferase from castor bean endosperm were considerably altered when contaminated fructose 6-phosphate was used as a substrate. Varying levels of fructose 2,6-bisphosphate in the substrate may account for differences that have been observed in the properties of the above enzyme from several plant sources.

Chromatography, Ion Exchange↗
PubMed1983

The effects of glucocorticoids on thymidine kinase and nucleoside phosphotransferase during development of chicken embryo retina.

Thymidine kinase in chick embryo retina reaches its highest values on the 8-10th day of development, then declines reaching the lowest value at hatching. The rate of DNA synthesis essentially follows this activity while, in contrast, nucleoside phosphotransferase increases progressively during development. Glucocorticoids at 5 X 10(-6) M lower the level of thymidine kinase in isolated retinas of chick embryo. The most effective steroid was hydrocortisone. The effect was observed in retinas from 8-18-day-old chick embryo and, except on the 8th day, was always of the same magnitude. We suggest that a glucocorticoid can be the natural factor responsible for the marked fall in thymidine kinase during development. Brief periods of exposure to steroids increase nucleoside phosphotransferase activity in isolated chick embryo retinas. When the exposure was longer than 3 h this activity was also clearly decreased. We conclude that other factors are responsible for the natural increment which occurs for this activity during development.

Animals↗
PubMed1985

Identification and measurement of D-glycero D-ido octulose 1,8-bisphosphate: D-altro-heptulose 7-phosphotransferase enzyme in tissues with L-type pentose phosphate pathway activity.

The enzyme D-glycero D-ido octulose 1,8-bisphosphate:D-altro-heptulose 7-phosphotransferase (abbreviated to phosphotransferase, PT) catalyses the transfer of the phosphate ester group at C-1 between altro-heptulose (sedoheptulose) and octulose phosphate intermediates of the L-type pentose pathway. Using synthetically prepared and 14C-labelled octulose mono- and bisphosphates, two methods are described for the measurement of the catalytic capacity of the PT reaction operating in both the "forward" and "reverse" modes of L-type pentose pathway operation. PT activity was found in normal, regenerating and foetal rat liver, rat heart, rat epididymal fat pad, rat kidney, brain and skeletal muscle, extracts of C. fusca, pea leaf and a variety of tumour tissues. The highest activity of the enzyme was found in the neoplasms. The Michaelian kinetic constants, temperature and pH optima for the reaction of the enzyme from rat liver together with an assortment of its substrate specificities have been determined. Vanadate anion was found to inhibit the enzyme and the pattern of inhibition suggests that the PT may act by a sequential mechanism. Neither arabinose 5-phosphate nor inorganic phosphate showed any effect on the catalytic activity of the PT enzyme in liver.

Animals↗
PubMed1987

Nucleotide sequence of the kanamycin resistance determinant of plasmid RP4: homology to other aminoglycoside 3'-phosphotransferases.

The kanamycin resistance determinant of the broad-host-range plasmid RP4 encodes an aminoglycoside 3'-phosphotransferase of type I. The nucleotide sequence of the kanamycin resistance gene (Kmr) and the right end of the insertion element IS8 of plasmid RP4 has been determined. The gene (816 bp) is located between IS8 and the region (Tra 1) encoding plasmid factors mediating bacterial conjugation. Kmr and Tra 1 are transcribed toward each other. The nucleotide sequence has been compared to five related aphA genes originating from gram-negative and gram-positive organisms and from antibiotic producers. Among these that of Tn903 shares the highest degree of similarity (60%) with the RP4 gene. Significant similarities were also detected between the amino acid sequences of the six enzymes. The C-terminal domains of six different aminoglycoside 3'-phosphotransferases (APH(3'] are highly conserved. They are substantially similar to segments of a variety of enzymes using ATP as cofactor. The role of the C-terminal sequences of APH(3') as potential domains for ATP recognition and binding is discussed.

Base Sequence↗
PubMed1989

Nucleotide sequence of a novel kanamycin resistance gene, aphA-7, from Campylobacter jejuni and comparison to other kanamycin phosphotransferase genes.

A novel kanamycin phosphotransferase gene, aphA-7, was cloned from a 14-kb plasmid obtained from a strain of Campylobacter jejuni and the nucleotide sequence of the gene was determined. The presumed open reading frame of the aphA-7 structural gene was 753 bp in length and encoded a protein of 251 amino acids with a calculated weight of 29,691 Da. A 29-kDa protein was demonstrated in Escherichia coli maxicells containing the cloned aphA-7 gene. A ribosomal binding site corresponding to 5 of 8 bases of the 3' end of the E. coli 16S rRNA was 8 bp upstream of the start codon. Sequences corresponding to the -35 and -10 regions of the consensus promoter sequences of E. coli were upstream of the presumed initiation codon of the gene. The DNA sequence was most closely related to the aphA-3 gene from Streptococcus faecalis, showing 55.4% sequence similarity. There was 45.6% identity at the amino acid level between the aphA-3 and the aphA-7 proteins. Of the three conserved regions noted previously in phosphotransferase genes, the aphA-7 amino acid sequence was identical to the six conserved amino acids in motif 3, but differed in one of the five conserved amino acids in motif 1 (if gaps are permitted) and 3 of the 10 conserved residues in motif 2. The 32.8% G + C ratio in the open reading frame of the aphA-7 kanamycin resistance gene, which is similar to that of the C. jejuni chromosome, suggests that the aphA-7 may be indigenous to Campylobacters.

Amino Acid Sequence↗
PubMed1993

Cytosolic 5'-nucleotidase/nucleoside phosphotransferase: a single assay for a bifunctional enzyme.

Cytosolic 5'-nucleotidase/nucleoside phosphotransferase has been purified from calf thymus. Since the same protein is able to catalyze both the hydrolysis and the interconversion of several nucleoside monophosphates, it is necessary to study the effect of different metabolites and assay conditions on both activities in order to elucidate their physiological roles. We describe herein a method which allowed us to follow both activities contemporaneously in the same assay mixture. The method takes advantage of the observation that deoxyGMP is both a good substrate for hydrolysis and a good phosphate donor for the phosphotransferase reaction, but its dephosphorylated product, deoxyguanosine, is not a phosphate acceptor. As a consequence, it is possible to follow both the deoxyguanosine production and the transfer of phosphate from deoxyGMP to the best phosphate acceptor, inosine, during the reaction, applying a method for the chromatographic separation on HPLC of both substrates (inosine and deoxyGMP) and both products (IMP and deoxyguanosine). The method was applied to the determination of the KM for inosine.

5'-Nucleotidase↗
PubMed1989

Presence of a fructose-2,6-bisphosphate-insensitive pyrophosphate: fructose-6-phosphate phosphotransferase in the anaerobic protozoa Tritrichomonas foetus, Trichomonas vaginalis and Isotricha prostoma.

Extracts of the anaerobic protozoa Tritrichomonas foetus, Trichomonas vaginalis and Isotricha prostoma contained a high activity (0.5-1 mumol min-1 (mg protein)-1) of pyrophosphate:fructose-6-phosphate phosphotransferase (PPi-PFK), but no detectable ATP: fructose-6-phosphate phosphotransferase. PPi-PFK from I. prostoma was purified close to homogeneity by adsorption on phospho-Ultrogel and elution with fructose-1,6-bisphosphate, and subsequent anion-exchange chromatography. The enzyme had an Mr of 95,000 as determined by gel filtration and consisted of subunits of Mr 48,000. PPi-PFK from I. prostoma and from T. foetus displayed hyperbolic kinetics with respect to their substrates and were not affected by fructose-2,6-bisphosphate. In sharp contrast with what has been found in other eukaryotes, no evidence could be found for the presence of fructose-2,6-bisphosphate in the two trichomonads, in I. prostoma and in Entamoeba histolytica.

Animals↗