The induced biosynthesis of 7-dehydrocholesterols in yeast: potential sources of new provitamin D3 analogs

1976 ◽  
Vol 54 (7) ◽  
pp. 657-665 ◽  
Author(s):  
L. Avruch ◽  
S. Fischer ◽  
H. Pierce Jr. ◽  
A. C. Oehlschlager
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Structural Analog ◽  
Side Chain ◽  
Low Concentrations ◽  
Potential Sources

The effect of low concentrations of a specifically designed sterol-24-transmethylase inhibitor, 25-aza-24,25-dihydrozymosterol (10) on sterol production in Saccharomyces cerevisiae was examined. The synthesis of cholesta-5,7,22,24-tetraen-3β-ol (4), its 7,22,24 analog (15) and the 7,24 analog (5) coupled with the availability of zymosterol (6) and cholesta-5,7,24-3β-ol (3) derivatives facilitated a search for these sterols in cultures treated with this inhibitor.When S. cerevisiae was grown in the presence of 1.3 and 5 μM10, it produced no ergosterol but accumulated zymosterol (6), cholesta-5,7,22, 24-tetraen-3β-ol (4) and related C27 sterols (3 and 5). These results indicate blockage of the side chain methylation that normally occurs during the biosynthesis of ergosterol in yeast by compound 10 is efficient. The cholesta-5,7,22,24-tetraen-3β-ol is a close structural analog of provitamin D3 (7-dehydrocholesterol). The inhibited yeast thus provides a source of a potentially new provitamin D3 substitute.

Backbone and side-chain resonance assignments of centromeric protein Scm3 from Saccharomyces cerevisiae

2019 ◽  
Vol 13 (2) ◽  
pp. 267-273
Author(s):  
Anusri Bhattacharya ◽  
Vaibhav Kumar Shukla ◽  
Ramakrishna V. Hosur ◽  
Ashutosh Kumar
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Resonance Assignments ◽  
Side Chain ◽  
Chain Resonance ◽  
Centromeric Protein ◽  
Side Chain Resonance

scholarly journals The effect of polyamines on the poly(adenylic acid)-induced inhibition of ribonuclease activity

1981 ◽  
Vol 193 (1) ◽  
pp. 325-337 ◽  
Author(s):  
T P Karpetsky ◽  
K K Shriver ◽  
C C Levy
Keyword(s):  
Human Plasma ◽  
Segment Length ◽  
Side Chain ◽  
Amino Groups ◽  
Human Spleen ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Adenylic Acid ◽  
Bovine Pancreas ◽  
Terminal Poly

Segments of poly(A) at the 3′-termini of 5 S rRNA inhibit the activities of ribonucleases from Citrobacter, Enterobacter, bovine pancreas, human spleen and human plasma. Certain polyamines, or compounds containing polyamine substructures, mediate reversal of this inhibition. Effective compounds contain three amino groups, at least two of which are charged and are separated from the others by no less than three carbon atoms. Spermidine and 9-aminoacridines, which contain substituted propyl- or butylamino moieties at the 9-amino position and which bear two positive charges per molecule, are efficacious at low concentrations (5 microM). A decrease in effectiveness is associated with the removal of one aromatic ring from the 9-aminoacridines. However, the resulting 4-aminoquinolines, unlike the acridines, do not inhibit enzyme activity when present in concentrations above 30 microM. Relocating the diamino side chain from the 4- to the 8-position of the quinoline nucleus causes a decrease in charge density to +1, with the result that such compounds are ineffective. The orders of polyamine efficacy of reversal of inhibition were similar for enzymes from Citrobacter, bovine pancreas, and human plasma, and paralleled the order of binding of polyamines to either poly(A) or 5 S rRNA. This was not the case with Enterobacter and human spleen RNAases, indicating that the identity of the most effective polyamines depends on the RNAase studied. The combination of variable 3′-terminal poly(A) segment length and polyamine identity and concentration constitutes a system by which RNAase activities, and, therefore, substrate-degradation rates, may be easily varied.

scholarly journals The introduction of the C-22–C-23 ethylenic linkage in ergosterol biosynthesis

1968 ◽  
Vol 106 (3) ◽  
pp. 623-626 ◽  
Author(s):  
M Akhtar ◽  
M. A. Parvez ◽  
P. F. Hunt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chemical Synthesis ◽  
Good Yield ◽  
The Other ◽  
Side Chain ◽  
Ergosterol Biosynthesis ◽  
Hydrogen Atoms ◽  
Whole Cells ◽  
C 23 ◽  
Methylene Derivative

Methods for the chemical synthesis of [23−3H2]lanosterol, [23,25−3H3]24-methyldihydrolanosterol and [24,28−3H2]24-methyldihydrolanosterol are described. It is shown that, in the biosynthesis of ergosterol from [26,27−14C2,23−3H2]lanosterol by the whole cells of Saccharomyces cerevisiae, one of the original C-23 hydrogen atoms is lost and the other is retained at C-23 of ergosterol. It is also shown that 24-methyldihydrolanosterol is converted into ergosterol in good yield and without prior conversion into a 24-methylene derivative. On the basis of these results possible pathways for the formation of the ergosterol side chain from a 24-methylene side chain are discussed.

Contribution of leucine 85 to the structure and function of Saccharomyces cerevisiae iso-1 cytochrome c

2001 ◽  
Vol 79 (4) ◽  
pp. 517-524 ◽  
Author(s):  
Jonathan C Parrish ◽  
J Guy Guillemette ◽  
Carmichael JA Wallace
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Electron Transfer ◽  
Electron Transport ◽  
Cytochrome C ◽  
Transport Processes ◽  
Complex Iii ◽  
Side Chain ◽  
Inner Mitochondrial Membrane ◽  
And Function ◽  
First Time

Cytochrome c is a small electron-transport protein whose major role is to transfer electrons between complex III (cytochrome reductase) and complex IV (cytochrome c oxidase) in the inner mitochondrial membrane of eukaryotes. Cytochrome c is used as a model for the examination of protein folding and structure and for the study of biological electron-transport processes. Amongst 96 cytochrome c sequences, residue 85 is generally conserved as either isoleucine or leucine. Spatially, the side chain is associated closely with that of the invariant residue Phe82, and this interaction may be important for optimal cytochrome c activity. The functional role of residue 85 has been examined using six site-directed mutants of Saccharomyces cerevisiae iso-1 cytochrome c, including, for the first time, kinetic data for electron transfer with the principle physiological partners. Results indicate two likely roles for the residue: first, heme crevice resistance to ligand exchange, sensitive to both the hydrophobicity and volume of the side chain; second, modulation of electron-transport activity through maintenance of the hydrophobic character of the protein in the vicinity of Phe82 and the exposed heme edge, and possibly of the ability of this region to facilitate redox-linked conformational change.Key words: protein engineering, cytochrome c, structure-function relations, electron transfer, hydrophobic packing.

Engineering oxidative stability in human hemoglobin based on the Hb providence (βK82D) mutation and genetic cross-linking

2017 ◽  
Vol 474 (24) ◽  
pp. 4171-4192 ◽  
Author(s):  
Michael Brad Strader ◽  
Rachel Bangle ◽  
Claire J. Parker Siburt ◽  
Cornelius L. Varnado ◽  
Jayashree Soman ◽  
...  
Keyword(s):  
Oxidative Degradation ◽  
Oxygen Affinity ◽  
Side Chain ◽  
Cross Linking ◽  
Critical Element ◽  
Low Oxygen ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Genetic Cross ◽  
Low Oxygen Affinity

Previous work suggested that hemoglobin (Hb) tetramer formation slows autoxidation and hemin loss and that the naturally occurring mutant, Hb Providence (HbProv; βK82D), is much more resistant to degradation by H2O2. We have examined systematically the effects of genetic cross-linking of Hb tetramers with and without the HbProv mutation on autoxidation, hemin loss, and reactions with H2O2, using native HbA and various wild-type recombinant Hbs as controls. Genetically cross-linked Hb Presbyterian (βN108K) was also examined as an example of a low oxygen affinity tetramer. Our conclusions are: (a) at low concentrations, all the cross-linked tetramers show smaller rates of autoxidation and hemin loss than HbA, which can dissociate into much less stable dimers and (b) the HbProv βK82D mutation confers more resistance to degradation by H2O2, by markedly inhibiting oxidation of the β93 cysteine side chain, particularly in cross-linked tetramers and even in the presence of the destabilizing Hb Presbyterian mutation. These results show that cross-linking and the βK82D mutation do enhance the resistance of Hb to oxidative degradation, a critical element in the design of a safe and effective oxygen therapeutic.

Growth performance and flesh quality of tilapia (Oreochromis niloticus) fed low concentrations of Rubrivivax gelatinosus, Saccharomyces cerevisiae and Spirulina platensis

2020 ◽  
Vol 28 (3) ◽  
pp. 1305-1317 ◽  
Author(s):  
Thiago Luís Magnani Grassi ◽  
Natália Mingues Paiva ◽  
Dayse Lícia Oliveira ◽  
Fábio Taniwaki ◽  
Jefferson Felipe Cavazzana ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Performance ◽  
Oreochromis Niloticus ◽  
Spirulina Platensis ◽  
Flesh Quality ◽  
Low Concentrations ◽  
Rubrivivax Gelatinosus

Gausemycins A,B – Cyclic Lipoglycopeptides from Streptomyces Sp.

2020 ◽  
Author(s):  
Anton Tyurin ◽  
Vera Alferova ◽  
Alexander Paramonov ◽  
Maxim Shuvalov ◽  
Gulnara Kudryakova ◽  
...  
Keyword(s):  
Cyclic Peptides ◽  
Pore Formation ◽  
Structural Features ◽  
Side Chain ◽  
Peptide Antibiotic ◽  
Streptomyces Sp ◽  
Gram Positive Bacteria ◽  
Low Concentrations ◽  
Phenylbutyric Acid ◽  
Peptide Core

We report a novel family of natural lipoglycopeptides produced by Streptomyces sp. INA-Ac-5812. Two major components of the mixture, named gausemycins A and B, were isolated, and their structures were elucidated. The compounds are cyclic peptides with a unique peptide core and several remarkable structural features, including unusual positions of D-amino acids, lack of the Ca2+ -binding Asp-X-Asp-Gly (DXDG) motif, tyrosine glycosylation with arabinose, presence of 2-amino-4-hydroxy-4- phenylbutyric acid (Ahpb) and chlorinated kynurenine (ClKyn), N-acylation of the ornithine side chain. These major components of the peptide antibiotic family have pronounced activity against Gram-positive bacteria. The mechanism of action of gausemycins was explored by a number of methods, showing significant differences compared to glycopeptides and related lipopeptides. For example, gausemycins exhibit no Ca2+ -dependence of antimicrobial activity and induce no pore formation at low concentrations. Moreover, there is no detectable accumulation of cell wall biosynthesis precursors under treatment with gausemycins.

scholarly journals Hydroxylation of the Herbicide Isoproturon by Fungi Isolated from Agricultural Soil

2005 ◽  
Vol 71 (12) ◽  
pp. 7927-7932 ◽  
Author(s):  
Stig Rønhede ◽  
Bo Jensen ◽  
Søren Rosendahl ◽  
Birthe B. Kragelund ◽  
René K. Juhler ◽  
...  
Keyword(s):  
Agricultural Soil ◽  
Dominant Mode ◽  
Bacterial Metabolism ◽  
Side Chain ◽  
Agricultural Field ◽  
Hydroxylated Metabolites ◽  
Low Concentrations ◽  
A Minor ◽  
Demethylated Metabolites ◽  
Minor Extent

ABSTRACT Several asco-, basidio-, and zygomycetes isolated from an agricultural field were shown to be able to hydroxylate the phenylurea herbicide isoproturon [N-(4-isopropylphenyl)-N′,N′-dimethylurea] to N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea and N-(4-(1-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea. Bacterial metabolism of isoproturon has previously been shown to proceed by an initial demethylation to N-(4-isopropylphenyl)-N′-methylurea. In soils, however, hydroxylated metabolites have also been detected. In this study we identified fungi as organisms that potentially play a major role in the formation of these hydroxylated metabolites in soils treated with isoproturon. Isolates of Mortierella sp. strain Gr4, Phoma cf. eupyrena Gr61, and Alternaria sp. strain Gr174 hydroxylated isoproturon at the first position of the isopropyl side chain, yielding N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea, while Mucor sp. strain Gr22 hydroxylated the molecule at the second position, yielding N-(4-(1-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea. Hydroxylation was the dominant mode of isoproturon transformation in these fungi, although some cultures also produced traces of the N-demethylated metabolite N-(4-isopropylphenyl)-N′-methylurea. A basidiomycete isolate produced a mixture of the two hydroxylated and N-demethylated metabolites at low concentrations. Clonostachys sp. strain Gr141 and putative Tetracladium sp. strain Gr57 did not hydroxylate isoproturon but N demethylated the compound to a minor extent. Mortierella sp. strain Gr4 also produced N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′-methylurea, which is the product resulting from combined N demethylation and hydroxylation.

Sign in / Sign up

Export Citation Format

Share Document