Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Starch biosynthesis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

32 records · Page 2Linked to original sources
PubMed1979

Regulative influence of o-aminobenzoic acid on the biosynthesis of nourseothricin in cultures of Streptomyces noursei JA 3890b. IV. Bistability of metabolism and the mechanism of action of aminobenzoic acids.

Using the semi-continuous cultivation technique we could establish that specifically in Streptomyces noursei JA 3890b during growth on a medium supplied with D,L-alanine, NH4+, and maize starch there are two different phenotypes of the organism and stationary states of metabolism, respectively. The expression of either the metabolic state I with an enhanced capacity to oxidative deamination of alanine via the NAD+-dependent alanaine dehydrogenase or the metabolic state 2 which may be characterized by the preferred use of ammonium ions via the NADP+-dependent glutamate dehydrogenase was shown to depend strongly on the conditions of inoculum cultivation. When the amino acid permeases were derepressed by cultivating the inoculum cells on amino acid media, probably due to the defective mechanism of negative feedback control of amino acid influx in this strain an abnormously high uptake of alanine was observed that, consequently, was correlated to the enhanced oxidation of this amino acid as well as to the intensive production of ammonia within the cell. This overproduction of cellular NH4+ seems to bring about the subsequent repression of biosynthetic glutamate dehydrogenase and so on the accumulation of ammonia autocatalytically may rise up (metabolic state I). On the other hand, if the influx of alanine was kept low and the NADH oxidation was less efficient, respectively, or when there was high cellular activity of glutamate dehydrogenase the level of ammonia never did exceed the respressory limit and, accordingly, the expression of the metabolic state 2 was observed. Switching-over of metabolic flux from the state 2 towards the state 1 can be brought about either by increasing the level of nitrogen sources in the medium or by adding buffers pH greater than 7.5. In contrast, decrease of cellular level of NH4+ was shown to induce the transition of metabolic state 1 into the state 2. This can be achieved not only by limitation of nitrogen source but also by adding different aminobenzoic acids and, alternatively, effectors of membrane function (short-chain alcohols), inhibitors of cytochrome oxidases (sodium azide, potassium cyanide), heavy metal (Fe++)-chelating agents (catechol, 2,5'-dipyridyl, o-phenanthroline), beta-alanine, and buffers pH less than 7. This suggests that these effectors are capable of preventing the abnormously high influx of amino acids as well as its wasteful catabolism within the cell of S. noursei JA 3890b. Therefore, it seems likely that by this way the aminobenzoic acids and similar effectors can diminish the catabolite repression or inhibition of secondary metabolism by cellular excess of some nitrogen compounds in good agreement with its well-known stimulatory action on the biosynthesis of the antibiotic nourseothricin in this strain.

Alanine↗
PubMedDate not supplied

[Activities of protein synthesis during the development of lethal nucleocytoplasmic hybrids obtained by nuclear graft between Ambystoma mexicanum Shaw and Ambystoma dumerilii Duges (Amphibia, Urodeles)].

A comparative study of proteinograms and zymograms (LDH, MDH) has been carried out at different ontogenic stages, in Ambystoma mexicanum (A.m.), Ambystoma dumerilii (A.d.) and nucleocytoplasmic hybrids 2 n A.d/cytoplasm Am. It appears that 2 n A.d. nucleus, grafted in A.m. cytoplasm expresses only a part of its potentialities, which could account for lethality of the nucleocytoplasmic hybrids.

Ambystoma↗
PubMedDate not supplied

[Influence of diets with qualitatively different carbohydrates on lipid metabolism].

Tests conducted with rats demonstrated that rations carrying saccharose cause a rise in the pre-beta-lipoproteids, blood triglycerides, total lipids and triglycerides in the aorta, as well as an accelerated biosynthesis of the latter in the liver and the fatty tissue. The effect of the saccharose making part of an isocaloric ration depends upon the quality of the diet as a whole. In rats receiving saccharose in a ration with a reduced amount of fat (11% bythe calorific value) there takes place an accelerated biosynthesis of phospholipids with no evidence of fatty degeneration of the liver. Animals receiving saccharose in a ration with a physiological level of fat (26% by caloricity) demonstrated a higher content of beta-lipoproteids in the blood, of total lipids and tryglycerides in the liver with lacking acceleration of the phospholipids biosynthesis in the latter.

Acetates↗
PubMedDate not supplied

[Effect of some amino acids on the biosynthesis of glucoamylase by cultured Endomycopsis species].

The effect of amino acids (glutamic, aspartic, beta-alanine, phenylalanine, methionine) on the glucoamylase biosynthesis by Endomycopsis species 20-9 was studied. Monoaminodicarboxylic acids produced a stimulating effect on the glucoamylase synthesis. Their addition at optimal concentrations of 0.2 to 0.4% increased by 54--69% glucoamylase activity of Endomycopsis sp. 20-9 upon submerged cultivation on the medium containing 3% maize extract and 1% starch. An application of this amino acid nutrition during cultivation did not produce a significant effect on the microbial glucoamylase activity.

Amino Acids↗
PubMed1978

Serum Neurophysins in familial central diabetes insipidus.

Antibovine neurophysin antibodies (anti-bNpI and/or anti-bNpII) are present in certain patients with familial central diabetes insipidus; these are exogenous origin, as they are not present in patients who have not received treatment with crude posterior pituitary extracts over the years preceding the analysis. Immunoreactive neurophysins were detectable in the blood of five patients with familial central diabetes insipidus, and in two of them, the levels increased after a short period of water restriction. There is marked polymorphism of these neurophysins from one serum to another: neurophysin I was consistently absent, while neurophysin II, accessory neurophysins, and other immunoreactive substances not present in normal sera were sometimes present in variable amounts. Immunoreactive AVP was undetectable in the urine of all patients, while immunoreactive OT was found in three of them; the latter substance could, however, be arginine vasotocin. Data are presented suggesting that the association between the biosynthesis of neurophysin I and AVP on the one hand, and neurophysin II and OT on the other hand is maintained in patients with isolated AVP deficiency on the basis of a congenital defect.

Adolescent↗
PubMed2026

Phytochrome-interacting factor 1b (SlPIF1b) affects the fruit quality of tomato by regulating chloroplast development.

The increased abundance and functionality of fruit chloroplasts could promote the accumulation of nutrients and flavor in the fruit. Tomato fruit has fully developed fruit chloroplasts, whose abundance and functionality have much untapped potential in improving fruit quality by controlling fruit chloroplast development. Previous studies have identified many regulatory factors that specifically regulate fruit chloroplast development in tomatoes, but there are fewer reports on tomato phytochrome-interacting factors (SlPIFs). Arabidopsis AtPIFs have been implicated in chloroplast development and chlorophyll biosynthesis. In this study, we identified and characterized an SlPIF1b mutant in tomato, named GS, which exhibited a dark green fruit shoulder with enhanced chloroplast development. RNA-seq and genotyping analysis identified a - 21 bp (A → T) mutation in the promoter of SlPIF1b, resulting in the absence of the TATA-box core transcriptional element and inhibiting SlPIF1b transcription. The overexpression of SlPIF1b in GS inhibited chloroplast development of fruits, leading to a lighter green shoulder color, decreased chlorophyll content, reduced photosynthetic activity, diminished starch accumulation, and compromised fruit quality upon ripening. Conversely, the down expression of SlPIF1b significantly enhanced fruit chloroplast development and functionality in fruits, resulting in increased chlorophyll and carotenoid accumulation. Further analysis of expression profile and transcriptional activity indicated that SlPIF1b could bind to G/PBE-box elements present in SlGLK2, SlTKN4, SlCAO1a, SlPOR1, SlPOR3, SlCAB1 and SlCAB1b promoters, thereby inhibiting their expression. This study revealed the specific regulatory mechanism by which SlPIF1b modulates chloroplast development and chlorophyll synthesis in tomato fruit and provided valuable genetic resources and a theoretical basis for tomato quality improvement.

Solanum lycopersicum↗
PubMed1976

[Studies on the initiation of glycogen metabolism in Escherichia coli (author's transl)].

Glycogen biosynthesis was studied in Escherichia coli. An enzyme complex composed of UDP-glucose; protein glucosyltransferase, ADP-glucose: protein glucosyltransferase and ADP-glucose: alpha-1,4 glucan alpha-4-glucosyltransferase was found. Further results revealed that while glycogen concentration remained unchanged, the specific activity of the glucosyltransferase complex increased during the growth phase of the culture. The detergents Lubrol and Brij provoked a decrease of 80% and 20% in the glucose transfer to protein from ADP-glucose and UDP-glucose, respectively. These detergents did not inhibit the glucose incorporation into glycogen by ADP-glucose: alpha-1,4-glucosyltransferase. We postulated that the biosynthesis of glycogen in Escherichia coli could be initiated by two different enzymes which catalyze the transfer of glucose from UDP-glucose or ADP-glucose to an acceptor protien. In a second step, the glucan protein formed is used as primer by the ADP-glucose: alpha-1,4 glucan alpha-1-glucosyltransferase for glycogen formation.

Detergents↗
PubMed1977

Hemoglobin S-O Arab-alpha-thalassemia: globin biosynthesis and clinical picture.

A 22 year old American negro with mild anemia was found to be triply heterozygous for hemoglobin S, hemoglobin O Arab and alpha thalassemia. Hemoglobin A was not detected in the subject's hemolysate. The alpha thalassemia gene was expressed by an alpha/non-alpha synthesis ratio of 0.71 plus or minus 0.07 and was equally rates unbalanced in the peripheral blood and the bone marrow. The total radioactivity of the abnormal chains was equal, indicating equal rates of transcription and translation of the abnormal structural genes. Since the rate of synthesis of betaS and betaO was equal to the proportions of these abnormal chains in the peripheral blood, the abnormal gene products were equally stable. The mildness of the anemia, compared to that of the other reported S-O Arab double heterozygotes, may be due to the moderating influene of the alpha thal gene.

Adult↗
PubMed1977

Translation of protamine mRNA in a rabbit reticulocyte cell-free system.

Protamine mRNA isolated from the microsomal and postribosomal supernatant fractions of trout testis in poly A(+) (polyadenylated RNA)and poly A (-) (RNA devoid of poly A(+)) forms (GEDAMU, L. & Dixon, G.H. (1976) J. Biol. Chem. 251, 1446-1454 and 1455-1463) was translated in the heterologous rabbit reticulocyte cell-free system; the products were shown to be identical in mobility with authentic protamine by polyacrylamide and starch gel electrophoresis. Chromatography, on carboxymethyl cellulose (Whatman CM-52), of the labelled polypeptide products synthesized in this cell-free system in the presence of poly A (+) and poly A(-) mRNA fractions also showed that [14C]arginine was incorporated into all three protamine components resolved in this system, but there was an unequal and variable incorporation of label into the three components with different preparations of mRNA. These results were interpreted as showing that the population of subcomponents of the protamine mRNA coding for the three different protamine polypeptides varied in batches of trout testis at differing stages of development. In addition, the proportion of mRNA components varied between the poly A(+) and poly A(-) editions of the mRNA, and it appeared that the poly A(-) mRNA fraction might represent the product of deadenylation of an earlier population of poly A(+) mRNA.

Animals↗
PubMed1978

Biosynthesis of bacterial glycogen. Isolation and characterization of the pyridoxal-P allosteric activator site and the ADP-glucose-protected pyridoxal-P binding site of Escherichia coli B ADP-glucose synthase.

[3H]Pyridoxal-P can be covalently incorporated into Escherichia coli B mutant strain AC70R1 ADP-glucose synthase by reduction with NaBH4. Two distinct lysine residues can be modified by the allosteric activator pyridoxal-P. Incorporation of [3H]pyridoxal-P in the presence of substrate ADP-glucose + MgCl2 prevents pyridoxylation of an ADP-glucose-protected site and allows modification of the allosteric activator site. Incorporation of [3H]pyridoxal-P in the presence of the allosteric effector, 1,6-hexanediol-P2, protects against pyridoxylation of the allosteric activator site and allows modification of the ADP-glucose-protected site. The activator site CNBr [3H]pyridoxyl-P peptide was purified to homogeneity in the presence of urea by Sephadex G-50 and CM-cellulose chromatography. The peptide consists of 59 residues, with a molecular weight of 6750. The NH2-terminal of the peptide has a 16-residue sequence overlap with the previously determined NH2-terminal sequence of the native enzyme. The activator site pyridoxyl-P lysine is identified as residue 38 of the native enzyme's NH2 terminus. The ADP-glucose-protected site CNBr [3H]pyridoxyl peptide was purified to homogeneity by Sephadex G-50 and DEAE-cellulose chromatography. The peptide consists of 21 residues, with a molecular weight of 2460. The sequence of this peptide has been elucidated.

Adenosine Diphosphate Glucose↗
PubMed1976

Biosynthesis of bacterial glycogen. Purification and properties of the Escherichia coli B ADPglucose:1,4-alpha-D-glucan 4-alpha-glucosyltransferase.

The Escherichia coli B glycogen synthase has been purified to apparent homogeneity with the use of a 4-aminobutyl-Sepharose column. Two fractions of the enzyme were obtained: glycogen synthase I with a specific activity of 380 mumol mg-1 and devoid of branching enzyme activity and glycogen synthase II having a specific activity of 505 mumol mg-1 and containing branching enzyme activity which was 0.1% of the activity observed for the glycogen synthase. Only one protein band was found in disc gel electrophoresis for each glycogen synthase fraction and they were coincident with glycogen synthase activity. One major protein band and one very faint protein band which hardly moved into the gel were observed in sodium dodecyl sulfate gel electrophoresis of the glycogen synthase fractions. The subunit molecular weight of the major protein band in sodium dodecyl sulfate gel electrophoresis of both glycogen synthase fractions was determined to be 49 000 +/- 2 000. The molecular weights of the native enzymes were determined by sucrose density gradient ultracentrifugation. Glycogen synthase I had a molecular weight of 93 000 while glycogen synthase II had a molecular weight of 200 000. On standing at 4 degrees C or at -85 degrees C both enzymes transform into species having molecular weights of 98 000, 135 000, and 185 000. Thus active forms of the E. coli B glycogen synthase can exist as dimers, trimers, and tetramers of the subunit. The enzyme was shown to catalyze transfer of glucose from ADPglucose to maltose and to higher oligosaccharides of the maltodextrin series but not to glucose. 1,5-Gluconolactone was shown to be a potent inhibitor of the glycogen synthase reaction. The glycogen synthase reaction was shown to be reversible. Formation of labeled ADPglucose occurred from either [14C]ADP or [14C]glycogen. The ratio of ADP to ADPglucose at equilibrium at 37 degrees C was determined and was found to vary threefold in the pH range of 5.27-6.82. From these data the ratio of ADP2- to ADPglucose at equilibrium was determined to be 45.8 +/- 4.5. Assuming that deltaF degrees of the hydrolysis of the alpha-1,4-glucosidic linkage is -4.0 kcal the deltaF degrees of hydrolysis of the glucosidic linkage in ADPglucose is -6.3 kcal.

Amylases↗