Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tetrahymena pyriformis were grown in proteose-peptone medium and then washed and incubated in a dilute salt solution for one hour. The cells were then discarded and the lysosomal hydrolases that had been secreted were subjected to DEAE cellulose column chromatography. At least three isoenzymes of acid phosphatase, three of acid protease, and two of beta-N-acetylhexoseaminidase were found, as well as single peaks of alpha-mannosidase, beta-galactosidase, and beta-fucosidase. The latter two activities were not resolved by the DEAE column and could not be separated in a second chromatographic step on CM-cellulose. Cells were also grown under identical conditions and homogenized in 0.25 M sucrose in order to allow comparison of some of the intracellular lysosomal hydrolases with their secreted counterparts. Two lysosomal populations were resolved by sucrose density gradient sedimentation, a heavy lysosomal fraction, contered at a density of about 1.25 gm/cm3, and a light lysosomal fraction, centered at a density of about 1.16 gm/cm3. These two populations differed in that the light lysosomes did not appear to contain significant amounts of beta-fucosidase, beta-galactosidase, or acid protease, whereas all six of the hydrolase activities studied were present in the heavy lysosomes. The light lysosomal peak occurred in cells grown to transition phase, but was markedly reduced in cells from cultures grown to stationary phase. In addition to these two fractions a third very light particle, containing only alpha-mannosidase activity, was detected just inside the gradient. Measurements were made of the effect of heat (10 minutes at 66 degrees) and of a change in pH from 4.5 (standard assay condition) to 6.0 on the three acid phosphatases and two beta-N-acetylhexoseaminidase isoenzymes resolved by DEAE column chromatography of the secreted hydrolases and on these hydrolyases in the heavy and light lysosomal fractions on the sucrose gradient. Use of the thermostability and pH criteria permitted computation of the expected properties of the intralysosomal acid phosphatase and hexoseaminidase activities if these consisted of the respective isoenzymes in the proportions secreted. It was found that neither the intralysosomal acid phosphatase nor the intralysosomal hexoseaminidase had the properties expected if they consisted of the secreted mixture of the respective isoenzymes, indicating that modification of some of these isoenzymes may have occurred during the 1-hour starvation period or after secretion.
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PMID:Lysosomal hydrolase secretion by Tetrahymena: a comparison of several intralysosomal enzymes with the isoenzymes released into the medium. 1 Mar 11

During recovery from silicate-starvation, a period of active DNA synthesis, synchronized cells of Cylindrotheca fusiformis incorporated 3 times more L-[U-14C]aspartate than did starved cells. Of the diatoms's four DNA polymerases, A and D are synthesized during silicate recovery, indicating that they are involved in silicate-dependent DNA replication. Polymerase B, and the chloroplast enzyme, polymerase C, are synthesized during silicate-starvation and their levels are unaffected by the addition of silicate. DEAE-Sephadex analysis of the DNA-binding proteins, labeled with [14C]- and [3H]asparate, shows that only three proteins are synthesized in cells recovering from silicate-starvation. Two of these proteins correspond to polymerases A and D, while the function of the third protein is not known. At least 15 other proteins are present in silicate-starved cells and their synthesis is repressed upon the addition of silicate. Models are proposed which describe the modes by which silicate might regulate DNA synthesis in the diatom.
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PMID:Role of silicon on diatom metabolism. IX. Differential synthesis of DNA polymerases and DNA-binding proteins during silicate starvation and recovery in Cylindrotheca fusiformis. 20 13

Saccharomyces cerevisiae X2180-1A synthesizes two forms of asparaginase: L-asparaginase I, an internal constitutive enzyme, and asparaginase II, an external enzyme which is secreted in response to nitrogen starvation. The two enzymes are biochemically and genetically distinct. The structural gene for asparaginase I (asp 1) is closely linked to the trp 4 gene on chromosome IV. The gene controlling the synthesis of asparaginase II is not linked to either the trp 4 or asp 1 genes. The rate of biosynthesis of asparaginase II is unaltered in yeast strains carrying the structural gene mutation for asparaginase I. Asparaginase II has been purified approximately 300-fold from crude extracts of Saccharomyces by heat and pH treatment, ethanol fractionation, ammonium sulfate fractionation followed by Sephadex G-25 chromatography, and DEAE-cellulose chromatography. Multiple activity peaks were obtained which, upon gas chromatographic analysis, exhibit varying mannose to protein ratios. Asparaginase I has been purified approximately 100-fold from crude extracts of Saccharomyces by protamine sulfate treatment, ammonium sulfate fractionation, gel permeation chromatography, and DEAE-cellulose chromatography. No carbohydrate component was observed upon gas chromatographic analysis. Comparative kinetic and analytic studies show the two enzymes have little in common except their ability to hydrolyze L-asparagine to L-aspartic acid and ammonia.
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PMID:Characterization of two forms of asparaginase in Saccharomyces cerevisiae. 34 21

The effect of amino acid starvation on the control of ribosome biosynthesis at the post-transcriptional level has been studied in Ehrlich ascites cells. A comparison of the turnover rates of ribosomal precursor RNA (pre-rRNA) and the degree of methylation of ribosomal RNA after histidine deprivation revealed that the slow down of ribosome formation is accompanied by a significant inhibition of rRNA methylation. Analysis of nucleolar and cytoplasmic RNA double-labelled with L-[Me-3H]methionine and [14C]uridine, as well as a quantitative determination of alkali-stable dinucleotides on DEAE-Sephadex, showed that methylation of rRNA species was inhibited by about 50% under shift-down conditions. This decrease in RNA methylation does not reflect an inhibition of rRNA methylases caused by amino acid starvation but is rather brought about by a shrinkage in the pool size of S-adenosylmethionine, the donor of methyl groups. It is suggested that amino acid starvation might exert its blocking effect on proper ribosome maturation by affecting the methylation of 45-S RNA.
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PMID:The effects of histidine starvation on the methylation of ribosomal RNA. 91 15

L-Leucine-pyruvate transaminase (mol. wt. 70 000) in Gluconobactersuboxydans synthesized during nitrogen starvation contained a labile form which changed to the stable one later. The labile enzyme (mol. wt. 70 000) dissocated to the two proteinaceous components: a cationic one (mol. wt. 10 000--20 000) and an anionic one (mol. wt. 50 000--60 000), during column chromatography on DEAE-cellulose. The enzyme activity was reconstructed when they were mixed. The reconstructed enzyme had almost the same molecular size and enzymatic properties as the labile and the native stable enzymes.
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PMID:Resolution and complementation of the labile L-leucine-pyruvate transaminase. An intermediate during enzyme formation under nitrogen starvation in Gluconobacter suboxydans. 100 28

Two isoenzymes of pyruvate kinase--PK-1 and PK-2 were obtained from the cortical layer of rabbit kidney by the method of chromatography on DEAE-cellulose. Starvation of rabbits for 10--16 days and alloxan diabetes produced no significant changes in the specific activity of PK in the soluble fraction obtained from the cortical layer of rabbit kidney. However, there were significant shifts in the isoenzymatic spectrum of the PK of the kidneys in rabbits with alloxan diabetes: the activity of the PK-1 increased considerably and significantly, and the isoenzyme PK-2 disappeared almost completely.
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PMID:[Pyruvate kinase isoenzymes in the kidneys of rabbits with insular insufficiency]. 112 47

In many eucaryotic systems protein synthesis is coupled to ribosomal RNA synthesis such that shut-down of the former causes inhibition of the latter. We have investigated this stringency phenomenon in HeLa cells. The protein synthesis inhibitors cycloheximide and puromycin cause inactivation of both processes but valine starvation totally inhibits only the processing of 45-S RNA. DNA-dependent RNA polymerases from A, B and C (or I, II and III respectively) were extracted, separated partially by DEAE-cellulose chromatography and their activity levels determined. These do not decrease significantly during inhibition of protein synthesis. To find out whether or not form A is bound to its template under these conditions, proteins were removed from chromatin with the detergent sarkosyl. This does not affect bound RNA polymerase. Inhibition of protein synthesis caused up to 50% reduction in endogenous alpha-amanitin-insensitive chromatin-RNA-synthesising activity. This reduced level of activity was not affected by sarkosyl treatment. Levels in normal cells were stimulated. This result indicates that the form A RNA polymerase is not bound to its template when protein synthesis is inhibited.
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PMID:Studies on the control of ribosomal RNA synthesis in HeLa cells. 117 42

An intracellular form of calcium ion-dependent transglutaminase (R-glutaminylpeptide:amine gamma-glutaminyltransferase, EC 2.3.2.13) was purified 818-fold to apparent homogeneity from acetone powder preparations of spherules of the acellular slime mold Physarum polycephalum. The enzyme was purified by combined methods of precipitation with 15% (wt/vol) polyethylene glycol, DEAE-cellulose chromatography, and isoelectric focusing in a pH 5 to 7 gradient. The isoelectric point of the enzyme was 6.1. The molecular mass of the denatured enzyme was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 39.6 kDa. A molecular weight of 77,000 was found by gel filtration of the native enzyme on a Superose 12 fast protein liquid chromatography column, indicating that the native functional protein is a dimer. The purified transglutaminase catalyzed the incorporation of [14C]putrescine into protein substrates including casein, N,N'-dimethylcasein, actin purified from P. polycephalum, and actin purified from bovine muscle. Actin was the preferred substrate for the enzyme, both as a purified protein and in crude extracts prepared from P. polycephalum. With N,N'-dimethylcasein as the amine acceptor substrate, [14C]putrescine, [14C]spermidine, and [14C]spermine were all effective amine donor substrates with Km values of 49, 21.4, and 31.7 microM, respectively. All three of these polyamines demonstrated strong substrate inhibition of the enzyme activity between 100 and 200 microM. Upon starvation induced by depletion of a carbon source for growth, the specific activity of this enzyme increased sixfold during the differentiation of P. polycephalum microplasmodia to spherules. This suggests a role for transglutaminase in the construction of spherules, which have the capacity to survive starvation and dessication.
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PMID:Purification and partial characterization of transglutaminase from Physarum polycephalum. 134 44

We show that N. crassa represses the production of acid phosphatase at pH higher than 8.0, irrespective of the carbon source used, whereas production was stimulated by sucrose at slightly acidic pH. The same profile of acid phosphatase production was observed in the pho-2A, pho-3A, nuc-1A, nuc-2A and pregc mutant strains. We also show that acid phosphatase synthesized by the pregc mutant strain grown on high phosphate medium has pronounced differences when compared to the enzyme synthesized by the wild-type strain grown on low phosphate medium in terms of heat stability, steady-state kinetic properties and DEAE-cellulose chromatography. In addition, the synthesis and/or secretion of only phosphate-repressible alkaline phosphatase is affected by mutations in acu-1, and acu-5 and acu-7 genes. These results, which indicate distinct pathways for the synthesis and secretion of acid and alkaline phosphatases in N. crassa, contradict the dosage titration model proposed by Metzenberg et al. (1974) whereby the synthesis of these enzymes should occur through a single hierarchical regulatory circuit as a response to phosphate starvation.
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PMID:Regulation of synthesis and secretion of acid and alkaline phosphatases in Neurospora crassa. 296 23

The formation of the oligosaccharide-lipid intermediates of the dolichol pathway by the bovine retina was investigated. Intact retinas were incubated in vitro for various periods of time in the presence of a variety of radioactive sugars (2-[3H]mannose, 6-[3H]glucose, 1-[3H]galactose, 1-[14C]glucosamine) using incubation conditions which have been shown previously to support the glycosylation of rhodopsin. The oligosaccharide-lipids were isolated and partially purified by DEAE cellulose chromatography. After mild acid hydrolysis and reduction, the oligosaccharides were analysed by HPLC. Further identification was obtained by chemical means and after digestion of the oligosaccharides with alpha-mannosidase and endohexosaminidase H. The full array of oligosaccharide-lipids which have been observed in other tissues were detected in the bovine retina, although some striking differences were seen in their relative distribution. Although short-term incubations (up to 15 min) indicated that the major species was the fully glucosylated oligosaccharide-lipid (Glc3Man9GlcNAc2), with longer incubation times the non-glucose-containing intermediate, Man9GlcNAc2, became the predominant species. Since glycerol was the carbon source for these incubations, the possibility was investigated that glucose starvation may have been the basis for this phenomenon, as has been reported in other tissues. It was established that this was not the case. Experiments carried out in the presence of castanospermine and bromoconduritol indicated that alpha-glucosidase activity in the retina may have resulted in the accumulation of the unglucosylated oligosaccharide-lipids. The formation of oligosaccharide-lipid intermediates by cells of the retinal pigment epithelium from the embryonic chick, maintained in cell culture, was also examined. In contrast to the bovine retina, the major species present were the glucose-containing intermediates, similar to other tissues.
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PMID:The dolichol pathway in the retina: oligosaccharide-lipid biosynthesis. 338 23


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