scholarly journals Phytochrome-induced synthesis of ribonuclease de novo in lupin hypocotyl sections

1974 ◽  
Vol 142 (3) ◽  
pp. 449-455 ◽  
Author(s):  
G. John Acton ◽  
Peter Schopfer
Keyword(s):  
Enzyme Activity ◽  
De Novo ◽  
Red Light ◽  
British Library ◽  
Band Broadening ◽  
Lending Library ◽  
Enzyme Molecules ◽  
Hypocotyl Tissue ◽  
Synthesis And Degradation ◽  
Isopycnic Centrifugation

1. Density-labelling with 99 atoms% of2H2O distinguished pre-existing from newly synthesized ribonuclease molecules in sections of developing hypocotyl tissue. 2. Activity profiles of enzyme extracted from the fraction pelletable at 100000g showed heterogeneity after isopycnic centrifugation in CsCl gradients. 3. Measurement of density shifts of the entire heterogeneous band shows that ribonuclease protein is synthesized de novo in both continuous far-red light and darkness. 4. A twofold increase in enzyme activity after irradiation was accompanied by band-broadening and a significantly faster rate of labelling than in darkness. 5. The conclusion is drawn from the experimental evidence and theoretical arguments presented that phytochrome regulates the synthesis of new enzyme molecules against a background of continuous (dark-rate) synthesis and degradation. 6. Further information has been deposited as Supplementary Publication SUP 50033 (3 pages) at the British Library Lending Division (formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1973), 131, 5.

scholarly journals Induction of dopa (3,4-dihydroxyphenylalanine) decarboxylase in blowfly integument by ecdysone. A demonstration of synthesis of the enzyme de novo

1975 ◽  
Vol 146 (1) ◽  
pp. 121-126 ◽  
Author(s):  
E G Fragoulis ◽  
C E Sekeris
Keyword(s):  
Enzyme Activity ◽  
Steroid Hormones ◽  
De Novo ◽  
Steroid Hormone ◽  
Dopa Decarboxylase ◽  
Double Labelling ◽  
Labelling Technique ◽  
Immune Precipitation ◽  
Enzyme Molecules ◽  
Stimulation Of

The activity of the enzyme dopa (3,4-dihydroxyphenylalanine) decarboxylase, present in the epidermis cells of blowfly larvae, increases during the late third instar under the influence of the steroid hormone, ecdysone. By using the double-labelling technique and immune precipitation with univalent antibody to dopa decarboxylase, we demonstrated that the increase in enzyme activity was due to a stimulation of synthesis of enzyme molecules de novo. In this respect, the action of ecdysone is similar to the action of other steroid hormones.

Use of a reversed-phase evaporation vesicle formulation for a homogeneous liposome immunoassay.

1986 ◽  
Vol 32 (9) ◽  
pp. 1687-1691 ◽  
Author(s):  
E Canova-Davis ◽  
C T Redemann ◽  
Y P Vollmer ◽  
V T Kung
Keyword(s):  
Enzyme Activity ◽  
Colorimetric Detection ◽  
Reversed Phase ◽  
Homogeneous Immunoassay ◽  
Bacterial Enzyme ◽  
Liposome Preparation ◽  
Enzyme Molecules ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Relevant Range ◽  
Serum Components

Abstract Complement-mediated release of enzyme molecules from reversed-phase evaporation vesicles serves as the basis of the sensitive homogeneous immunoassay reported here. We found it necessary to co-entrap the substrate glucose 6-phosphate with the bacterial enzyme glucose-6-phosphate dehydrogenase (EC 1.1.1.49) to protect enzyme activity during liposome preparation. Enzyme can be released specifically from these liposomes by incubation with antibody and complement. the enzyme is not merely available to substrate but is actually physically free of the liposomes. Inhibition of this complement-mediated lysis by theophylline is the basis for the homogeneous liposome immunoassay described. The assay results vary linearly with theophylline concentrations in plasma in the clinically relevant range, and serum components do not interfere. The reagents in the assay kit are stable for at least seven months when stored at 5 degrees C. No nontheophylline compounds reacted significantly with the antiserum used. The assay can be run in a kinetic format, with either ultraviolet or colorimetric detection.

scholarly journals Enhancing a de novo enzyme activity by computationally-focused ultra-low-throughput screening

2020 ◽  
Vol 11 (24) ◽  
pp. 6134-6148 ◽  
Author(s):  
Valeria A. Risso ◽  
Adrian Romero-Rivera ◽  
Luis I. Gutierrez-Rus ◽  
Mariano Ortega-Muñoz ◽  
Francisco Santoyo-Gonzalez ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
De Novo ◽  
Library Screening ◽  
Natural Reaction

De novo enzymes capable of efficiently catalysis of a non-natural reaction are obtained through minimalist design plus computationally-focused variant library screening.

D-Serine metabolism: new insights into the modulation of D-amino acid oxidase activity

2013 ◽  
Vol 41 (6) ◽  
pp. 1551-1556 ◽  
Author(s):  
Silvia Sacchi
Keyword(s):  
Enzyme Activity ◽  
Amino Acid ◽  
Oxidase Activity ◽  
Acid Oxidase ◽  
Endogenous Ligand ◽  
Amino Acid Oxidase ◽  
The Brain ◽  
Serine Metabolism ◽  
Synthesis And Degradation

Over the years, accumulating evidence has indicated that D-serine represents the main endogenous ligand of NMDA (N-methyl-D-aspartate) receptors. In the brain, the concentration of D-serine stored in cells is defined by the activity of two enzymes: serine racemase (responsible for both the synthesis and degradation) and D-amino acid oxidase (which catalyses D-serine degradation). The present review is focused on human D-amino acid oxidase, discussing the mechanisms involved in modulating enzyme activity and stability, with the aim to substantiate the pivotal role of D-amino acid oxidase in brain D-serine metabolism.

Induction de la synthèse de la δ-aminolévulinate déshydratase des cotylédons de radis étiolés ou cultivés sous lumière rouge lointain par l'érythromycine

1985 ◽  
Vol 63 (5) ◽  
pp. 950-954
Author(s):  
Claude Huault ◽  
Philippe Bruyant ◽  
Alain-Pierre Balangé
Keyword(s):  
De Novo ◽  
Red Light ◽  
Nuclear Genome ◽  
De Novo Synthesis ◽  
Aminolevulinate Dehydratase

Erythromycin stimulates the de novo synthesis of δ-aminolevulinate dehydratase of radish cotyledons in both far-red light and darkness and blocks the enzyme accumulation in the etioplast. Density labelling experiments using erythromycin and cycloheximide demonstrate that δ-aminolevulinate dehydratase is encoded by the nuclear genome and that its synthesis is controlled by the etioplast.

scholarly journals Acid phosphatase and cathepsin activity in cuttlefish (Sepia officinalis) eggs: the effects of Ag, Cd, and Cu exposure

2010 ◽  
Vol 67 (7) ◽  
pp. 1517-1523 ◽  
Author(s):  
Thomas Lacoue-Labarthe ◽  
Estelle Le Bihan ◽  
David Borg ◽  
Noussithé Koueta ◽  
Paco Bustamante
Keyword(s):  
Heavy Metals ◽  
Enzyme Activity ◽  
Acid Phosphatase ◽  
Embryonic Development ◽  
Enzyme Activities ◽  
De Novo ◽  
Sepia Officinalis ◽  
Activity Levels ◽  
Cathepsin Activity ◽  
Hatchling Weight

Abstract Lacoue-Labarthe, T., Le Bihan, E., Borg, D., Koueta, N., and Bustamante, P. 2010. Acid phosphatase and cathepsin activity in cuttlefish (Sepia officinalis) eggs: the effects of Ag, Cd, and Cu exposure. – ICES Journal of Marine Science, 67: 1517–1523. Changes in the activity levels of acid phosphatase (AcP) and cathepsin during cuttlefish embryo development are described, as are the effects of exposure to heavy metals. Enzyme activity kinetics appear to be linked to the developmental stage. The activities of both enzymes increased during the final days of development, suggesting de novo production by the maturing embryo in the digestive gland. The effects of selected heavy metals, Ag (0.06, 1.2, 60, 1200 ng l−1), Cd (31, 61, 305, 610 ng l−1), and Cu (0.23, 2.3, 23, 230 µg l−1), were assessed based on AcP and cathepsin activities at the end of embryonic development and on hatchling weight. Enzyme activities were not impacted by Ag but were significantly inhibited by Cd, at all four concentrations for AcP and at 610 ng l−1 for cathepsin. Cu (at 2.3 µg l−1) stimulated AcP activity. No cause–effect relationship was found between the effects of metals on the enzyme activities and hatchling weight, suggesting that heavy metals could affect other physiological functions during embryogenesis.

Effect of Microwave Treatment on Catalysis of Papain

2012 ◽  
Vol 554-556 ◽  
pp. 1237-1242
Author(s):  
Xu Cong Yu ◽  
Lin Li ◽  
Quan Yi Fu ◽  
Bing Li
Keyword(s):  
Enzyme Activity ◽  
Fluorescence Spectroscopy ◽  
Enzyme Catalysis ◽  
Ph Value ◽  
Microwave Treatment ◽  
Microwave Processing ◽  
Disodium Edta ◽  
Optimum Ph ◽  
Enzyme Molecules ◽  
Main Factor

In this article, investigation on the effect of microwave treatment on the catalysis of papain had been carried out. According to the results, the thermal effect was found to be the main factor to cause inactivation of enzyme. The kinetic parameters and the fluorescence spectroscopy implied that the microwave processing had changed the conformation of the enzyme molecules and thus affected its activity. The results also showed that the microwave treatment had not changed the optimum pH value of the enzyme catalysis, and the inactivation rate of the enzyme was inversely proportional to the concentration of the enzyme. In addition, a certain concentration of the disodium EDTA media had been found to effectively protect the enzyme activity in microwave processing.

scholarly journals De novo methylation of CpG island sequences in human fibroblasts overexpressing DNA (cytosine-5-)-methyltransferase.

1996 ◽  
Vol 16 (8) ◽  
pp. 4555-4565 ◽  
Author(s):  
P M Vertino ◽  
R W Yen ◽  
J Gao ◽  
S B Baylin
Keyword(s):  
Enzyme Activity ◽  
De Novo ◽  
Cpg Island ◽  
Human Fibroblasts ◽  
Methylation Status ◽  
Cpg Islands ◽  
Parental Cell Line ◽  
Direct Role ◽  
Cpg Island Methylation ◽  
De Novo Methylation

Recent studies showing a correlation between the levels of DNA (cytosine-5-)-methyltransferase (DNA MTase) enzyme activity and tumorigenicity have implicated this enzyme in the carcinogenic process. Moreover, hypermethylation of CpG island-containing promoters is associated with the inactivation of genes important to tumor initiation and progression. One proposed role for DNA MTase in tumorigenesis is therefore a direct role in the de novo methylation of these otherwise unmethylated CpG islands. In this study, we sought to determine whether increased levels of DNA MTase could directly affect CpG island methylation. A full-length cDNA for human DNA MTase driven by the cytomegalovirus promoter was constitutively expressed in human fibroblasts. Individual clones derived from cells transfected with DNA MTase (HMT) expressed 1- to 50-fold the level of DNA MTase protein and enzyme activity of the parental cell line or clones transfected with the control vector alone (Neo). To determine the effects of DNA MTase overexpression on CpG island methylation, we examined 12 endogenous CpG island loci in the HMT clones. HMT clones expressing > or = 9-fold the parental levels of DNA MTase activity were significantly hypermethylated relative to at least 11 Neo clones at five CpG island loci. In the HMT clones, methylation reached nearly 100% at susceptible CpG island loci with time in culture. In contrast, there was little change in the methylation status in the Neo clones over the same time frame. Taken together, the data indicate that overexpression of DNA MTase can drive the de novo methylation of susceptible CpG island loci, thus providing support for the idea that DNA MTase can contribute to tumor progression through CpG island methylation-mediated gene inactivation.

scholarly journals The molecular and crystal structures of 4-N-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-l-asparagine trihydrate and 4-N-(β-d-glucopyranosyl)-l-asparagine monohydrate. The X-ray analysis of a carbohydrate–peptide linkage

1974 ◽  
Vol 143 (1) ◽  
pp. 197-205 ◽  
Author(s):  
L. T. J. Delbaere
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Torsion Angle ◽  
Chair Conformation ◽  
Amide Group ◽  
British Library ◽  
X Ray ◽  
Peptide Linkage ◽  
Lending Library ◽  
The Mean

X-ray analyses have shown that the glucopyranose rings of GlcNAc-Asn [4-N-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-l-asparagine] and Glc-Asn [4-N-(β-d-glucopyranosyl)-l-asparagine] both have the C-1 chair conformation and also that the glucose–asparagine linkage of each molecule is present in the β-anomeric configuration. The dimensions (the estimated standard deviations of the last digit are in parentheses) of the glycosidic bond in GlcNAc-Asn and Glc-Asn are, respectively, C(1)-N(1) 0.1441(6)nm, 0.146(2)nm; angle O(5)-C(1)-N(1) 106.8(3)°, 105.7(8)° angle C(2)-C(1)-N(1) 111.1(4)°, 110.4(9)° angle C(1)-N(1)-C(9) 121.4(4)°, 120.5(9)°. The glycosidic torsion angle C(9)-N(1)-C(1)-C(2) is 141.0° and 157.6° in GlcNAc-Asn and Glc-Asn respectively. Hydrogen-bonding is extensive in these two crystal structures and does affect one torsion angle in particular. Two very different values of χ1(N-Cα-Cβ-Cγ) occur for the asparagine residue of the two different molecules; the values of χ1, −69.0° in GlcNAc-Asn and 61.9° in Glc-Asn, correspond to two different staggered conformations about the Cα-Cβbond as the NH3+group is adjusted to different hydrogen-bonding patterns. The two trans-peptide groups in GlcNAc-Asn show small distortions in planarity whereas that in Glc-Asn is more non-planar. The mean plane through the atoms of the amide group at C(2) in GlcNAc-Asn is approximately perpendicular (69°) to the mean plane through the C(2), C(3), C(5) and O(5) atoms of the glucose ring and that at C(1) is less perpendicular (65°). The mean plane through the atoms of the amide group in Glc-Asn makes an angle of only 55° with the mean plane through these same four atoms of the glucose ring. The N(1)-H bond of the amide at C(1) is trans to the C(1)-H bond in these two compounds; the N(2)-H bond of the amide at C(2) is trans to the C(2)-H bond in GlcNAc-Asn. The values of the observed and final calculated structure amplitudes have been deposited as Supplementary Publication SUP 50035 (26 pages) at the British Library (Lending Division), (formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem. J. (1973) 131, 5.

Temperature Dependent Conformation Changes of Ribulose-1,5-bisphosphate Carboxylase Studied by the Use of 1-Anilino-8-naphthalene Sulfonate

1977 ◽  
Vol 32 (3-4) ◽  
pp. 226-228 ◽  
Author(s):  
Günter F. Wildner ◽  
Jürgen Henkel
Keyword(s):  
Enzyme Activity ◽  
Binding Sites ◽  
Fluorescence Probe ◽  
Fluorescence Emission ◽  
Binding Constants ◽  
Temperature Dependent ◽  
Bisphosphate Carboxylase ◽  
Influence Of Temperature On ◽  
Number Of Binding Sites ◽  
Enzyme Molecules

Abstract The influence of temperature on the structure and enzyme activity of ribulose-1,5-bisphosphate carboxylase, isolated from Euglena gracilis cells, was studied. Freezing of the purified ribulose-1,5-bisphosphate carboxylase preparation causes a severe loss of enzyme activity, which can be restored again by incubation of the enzyme molecules at higher temperatures (50 °C). The titration of both enzyme samples with the fluorescence probe 1-anilino-8-naphthalene sulfonate (ANS) re­vealed an increase of the fluorescence emission of the low temperature form of the enzyme. Two different enzyme conformations can be assumed which differ in the number of binding sites for ANS and Vmax values for the carboxylase reaction but show similar binding constants for ANS and the apparent Km values for C02 .

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