Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CoAs”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Biotin attachment domain-containing proteins mediate hydroxy fatty acid-dependent inhibition of acetyl CoA carboxylase

Hundreds of naturally occurring specialized fatty acids (FAs) have potential as desirable chemical feedstocks if they could be produced at large scale by crop plants; however, transgenic expression of their biosynthetic genes has generally been accompanied by dramatic reductions in oil yield. For example, expression of castor (Ricinus communis) FA hydroxylase (FAH) in the Arabidopsis thaliana FA elongation mutant fae1 resulted in a 50% reduction of FA synthesis rate that was attributed to inhibition of acetyl-CoA carboxylase (ACCase) by an undefined mechanism. Here, we tested the hypothesis that the ricinoleic acid-dependent decrease in ACCase activity is mediated by biotin attachment domain-containing (BADC) proteins. BADCs are inactive homologs of biotin carboxy carrier protein that lack a biotin cofactor and can inhibit ACCase. Arabidopsis contains three BADC genes. To reduce expression levels of BADC1 and BADC3 in fae1/FAH plants, a homozygous badc1,3/fae1/FAH line was created. The rate of FA synthesis in badc1,3/fae1/FAH seeds doubled relative to fae1/FAH, restoring it to fae1 levels, increasing both native FA and HFA accumulation. Total FA per seed, seed oil content, and seed yield per plant all increased in badc1,3/fae1/FAH, to 5.8 µg, 37%, and 162 mg, respectively, relative to 4.9 µg, 33%, and 126 mg, respectively, for fae1/FAH. Transcript levels of FA synthesis-related genes, including those encoding ACCase subunits, did not significantly differ between badc1,3/fae1/FAH and fae1/FAH. These results demonstrate that BADC1 and BADC3 mediate ricinoleic acid-dependent inhibition of FA synthesis. We propose that BADC-mediated FAS inhibition as a general mechanism that limits FA accumulation in specialized FA-accumulating seeds.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Disruption of p -coumaroyl-CoA:monolignol transferases in rice drastically alters lignin composition

Grasses are abundant feedstocks that can supply lignocellulosic biomass for production of cell-wall-derived chemicals. In grass cell walls, lignin is acylated with p-coumarate. These p-coumarate decorations arise from the incorporation of monolignol p-coumarate conjugates during lignification. A previous biochemical study identified a rice (Oryza sativa) BAHD acyltransferase (AT) with p-coumaroyl-CoA:monolignol transferase (PMT) activity in vitro. In this study, we determined that that enzyme, which we name OsPMT1 (also known as OsAT4), and the closely related OsPMT2 (OsAT3) harbor similar catalytic activity toward monolignols. We generated rice mutants deficient in either or both OsPMT1 and OsPMT2 by CRISPR/Cas9-mediated mutagenesis and subjected the mutants’ cell walls to analysis using chemical and nuclear magnetic resonance methods. Our results demonstrated that OsPMT1 and OsPMT2 both function in lignin p-coumaroylation in the major vegetative tissues of rice. Notably, lignin-bound p-coumarate units were undetectable in the ospmt1 ospmt2-2 double-knockout mutant. Further, in-depth structural analysis of purified lignins from the ospmt1 ospmt2-2 mutant compared with control lignins from wild-type rice revealed stark changes in polymer structures, including alterations in syringyl/guaiacyl aromatic unit ratios and inter-monomeric linkage patterns, and increased molecular weights. Furthermore, our results provide insights into lignin polymerization in grasses that will be useful for the optimization of bioengineering approaches for the effective use of biomass in biorefineries.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Evolution of the regulatory subunits for the heteromeric acetyl-CoA carboxylase

The committed step for de novo fatty acid (FA) synthesis is the ATP-dependent carboxylation of acetyl-coenzyme A catalysed by acetyl-CoA carboxylase (ACCase). In most plants, ACCase is a multi-subunit complex orthologous to prokaryotes. However, unlike prokaryotes, the plant and algal orthologues are comprised both catalytic and additional dedicated regulatory subunits. Novel regulatory subunits, biotin lipoyl attachment domain-containing proteins (BADC) and carboxyltransferase interactors (CTI) (both three-gene families inArabidopsis) represent new effectors specific to plants and certain algal species. The evolutionary history of these genes in autotrophic eukaryotes remains elusive, making it an ongoing area of research. Analyses of potential protein–protein and co-occurrence interactions, informed by gene network patterns using the STRING database, inArabidopsis thalianaandChlamydomonas reinhardtiiunveil intricate gene associations with ACCase, suggesting a complex interplay between FA synthesis and other cellular processes. Among both species, a higher number of co-expressed genes was identified inArabidopsis, indicating a wider potential regulatory network of ACCase in plants. This review investigates the extent to which these genes arose in autotrophic eukaryotes and provides insights into their evolutionary trajectory. This article is part of the theme issue ‘The evolution of plant metabolism’.

Life Sciences & Biomedicine - Other Topics↗
DOE OSTI2026

Simultaneous Overexpression of FERULOYL‐CoA 6′‐HYDROXYLASE 1 and COUMARIN SYNTHASE Leads to Coumarin‐Enriched Lignin and Improved Saccharification in Greenhouse‐ and Field‐Grown Poplar

ABSTRACT The urgent need for renewable resources has increased the interest in woody biomass to manufacture bio‐based products. However, lignin recalcitrance limits the enzymatic conversion of wood into fermentable sugars, posing a major challenge for biomass deconstruction. To address this problem, we aimed at incorporating the coumarin scopoletin into the lignin polymer of poplar ( Populus tremula × P . alba ) by expressing FERULOYL‐CoA 6′‐HYDROXYLASE 1 ( F6′H1 ) and COUMARIN SYNTHASE ( COSY ) in lignifying cells. Three constructs were evaluated: two bicistronic constructs, SCOP1 ( COSY followed by F6′H1 ) and SCOP2 ( F6′H1 followed by COSY ), and one monocistronic, SCOP3 (only F6′H1 ). SCOP1 poplars produced most free scopoletin without altering overall lignin, cellulose or hemicellulose content. SCOP2 poplars were overall less efficient in scopoletin production and most of these lines showed a severe biomass yield penalty, whereas SCOP3 caused plant lethality. NMR and metabolic analyses confirmed that scopoletin cross‐coupled with G and S monomers during lignification in SCOP1 lines. In addition to scopoletin, the detection of benzodioxane structures revealed the incorporation of dihydroxycoumarins. Overall coumarin incorporation in lignin amounted up to 2.3%. After alkaline pretreatment, wood from greenhouse‐grown SCOP1 poplars released up to 29% more glucose compared to the wild type upon limited saccharification. Field‐testing of three SCOP1 lines showed a 6 to 11% increase in saccharification efficiency, with the line containing the lowest scopoletin levels maintaining normal growth. These results demonstrate that engineering lignin composition in poplar can improve saccharification, and emphasize the importance of construct design, translational research and field validation.

alternative lignin monomers↗
DOE OSTI2026

Telomere-to-telomere assemblies of chromosome 10 reveal complex adaptive variation of 3-ketoacyl-CoA-synthases in Populus trichocarpa likely driven by Helitrons

The model woody plant Populus trichocarpa displays an atypical alkene-diverse wax cuticle likely driven by copy number variation (CNV) of 3-ketoacyl-CoA synthases ( KCS ), which has been difficult to confirm with short-read assemblies. Long-read sequencing enables the development of telomere-to-telomere resources to detect cryptic variation, including CNVs, which are currently missed. Integrating this information can improve genomic prediction for breeding and provide insights into the evolutionary basis of important traits. Our analysis of 78 long-read haplotypes from chromosome 10 identified more than twice as many KCS genes as previously reported, and numerous intragenic non-synonymous substitutions. Random Forest predictive models highlighted the importance of Potri.010G079500 in producing very long chain alkenes; however, its absence did not predict previously reported alkene-deficient phenotypes. Instead, alkene levels are best predicted by the combinations of KCS copies. Additionally, amino acid substitutions clustered around ligand and donor binding pockets, suggesting they contribute to differing wax cuticle composition. Finally, each KCS gene and copy was linked to a Helitron transposon. A phylogenetic analysis suggests Helitrons are the evolutionary mechanism for generating KCS tandem arrays. Long-read generated telomere-to-telomere assemblies of P. trichocarpa chromosome 10 revealed large-effect loci critical to genetic studies that are unattainable from short-reads. This new resource produced novel insights into genome structure and function, and a novel mechanism for generating tandem gene duplication. Our results highlight that, given current challenges in annotation and assembly, detailed and focused long-read sequences are key to interpreting complex genomic regions that contain tandem copy number variants.

09 BIOMASS FUELS↗
NASA NTRS1976

Stability Characteristics of "Aerobic" Acetyl-CoA Synthetase of Yeast

During the purification of the "aerobic" acetyl-CoA synthetase (ACS) of Saccharomyces cerevisiae, strain LK2Gl2, it was noted that stronge at 4 C resulted in the loss of enzyme activity within 24 hr. Similar losses were observed during column chromatography. Addition of boiled extracts from either aerobic or anerobic cells completely prevents this. The stabilizing factor (SF) in these extracts is non-dialyzable and organic in nature. SF is excluded on G-25 and G-50 Sephadex columns and is slightly retarded on G-75 columns. On G-100 columns, SF elutes as a peak exactly coincident with that of cytochrome c, indicating a molecular weight of 13,000. SF activity was not destroyed by Pronase treatment, was adsorbed onto Norite, and absorbed in the UV with a single maximum at 260 nm. The action of SF could be replaced by a number of nucleotides. At 0.01 M, the order of effectiveness was: ATP>ADP>AMP>GTP>CTP>/=UTP>XTP. Even at 2 x 10(exp -4) M, ATP and ADP, but not AMP, cyclic AMP, adenosine or adenine, were effective in stabilizing this ACS. The mechanism of stabilization by ATP and AMP appears to be the same, since AMP competitively inhibited the ACS with respect to ATP in in vitro assays, while ADP gave a mixed type of inhibition, thus indicating a different mechanism. ACS from nonaerobic cells is also unstable in the absence of SF but, unlike aerobic ACS, is not affected by ATP or other nucleotides.

Satyanarayana, T.↗
NASA NTRS2001

Distribution and Spectroscopy of Green Fluorescent Protein and Acyl-CoA: Cholesterol Acytransferase in Sf21 Insect Cells

Acyl-CoA: cholesterol acyltransferase (ACAT) is thought to significantly participate in the pathway of cholesterol esterification that underlies the pathology of artherosclerosis. This enzyme is a membrane protein known to be preferentially bound within the endoplasmic reticulum of mammalian cells, from which location it esterifies cholesterol derived from low density lipoprotein. Cultures of insect cells were separately infected with baculovirus containing the gene for green fluroescent protein (GFP) and with baculovirus containing tandem genes for GFP and ACAT. These infected cultures expressed GFP and the fusion protein GCAT, respectively, with maximum expression occurring on the fourth day after infection. Extraction of GFP- and of GCAT-expressing cells with urea and detergent resulted in recovery of fluorescent protein in aqueous solution. Fluorescence spectra at neutral pH were identical for both GFP and GCAT extracts in aqueous solution, indicating unperturbed tertiary structure for the GFP moiety within GCAT. In a cholesterol esterification assay, GCAT demonstrated ACAT activity, but with less efficiency compared to native ACAT. It was hypothesized that the membrane protein ACAT would lead to differences in localization of GCAT compared to GFP within the respective expressing insect cells. The GFP marker directly and also within the fusion protein GCAT was accordingly used as the intracellular probe that was fluorescently analyzed by the new biophotonics technique of hyperspectral imaging. In that technique, fluorescence imaging was obtained from two dimensional arrays of cells, and regions of interest from within those images were then retrospectively analyzed for the emission spectra that comprises the image. Results of hyperspectral imaging of insect cells on day 4 postinfection showed that GCAT was preferentially localized to the cytoplasm of these cells compared to GFP. Furthermore, the emission spectra obtained for the localized GCAT displayed a peak blue shift from 518nm obtained in neutral aqueous solution to 505nm obtained in localized regions within the cells. This blue shift indicates change in the fluorescence coupling of the GFP moiety of GCAT. It is hypothesized that change in tertiary environment of GCAT, coincident with intracellular deposition of GCAT, follows from intracellular trafficking of GCAT leading to membrane interactions with the ACAT moiety, and/or self-assembly of GCAT, that alters the chromophore environment of the GFP moiety of GCAT. These findings introduce a new technique of biophotonic imaging to studies of intracellular protein trafficking and interactions. This technique of hyperspectral imaging could contribute to advancing the emergent field of proteomics. Because of the noninvasive nature of this technique, kinetic processes associated with intracellular protein trafficking, and interactions of proteins within cellular domains, can be considered for investigation within a single cell as well as a cell population.

Richmond, R. C.↗
NASA NTRS2001

Hyperspectral Imaging and Spectroscopy of Fluorescently Coupled Acyl-CoA: Cholesterol Acyltransferase in Insect Cells

A high-performance hyperspectral imaging module with high throughput of light suitable for low-intensity fluorescence microscopic imaging and subsequent analysis, including single-pixel-defined emission spectroscopy, was tested on Sf21 insect cells expressing green fluorescence associated with recombinant green fluorescent protein linked or not with the membrane protein acyl-CoA:cholesterol acyltransferase. The imager utilized the phenomenon of optical activity as a new technique providing information over a spectral range of 220-1400 nm, and was inserted between the microscope and an 8-bit CCD video-rate camera. The resulting fluorescence image did not introduce observable image aberrations. The images provided parallel acquisition of well resolved concurrent spatial and spectral information such that fluorescence associated with green fluorescent protein alone was demonstrated to be diffuse within the Sf21 insect cell, and that green fluorescence associated with the membrane protein was shown to be specifically concentrated within regions of the cell cytoplasm. Emission spectra analyzed from different regions of the fluorescence image showed blue shift specific for the regions of concentration associated with the membrane protein.

Malak, H.↗
NASA NTRS2002

Synthesis and thermoeletric properties of Co(sub (1-x)ni)(sub X)P(sub 3) and CoAs((sub 3-x))P(sub x) skutterudites

Two types of promising phosphide skutterudite materials, Co(1-x)NixP3 (x= 0.025 to 0.70) and CoAs(3-x)Px (x=0.5 to 0.10), have been synthesized and their transport properties measured. These compounds were prepared using a direct synthesis technique. The samples were hot pressed and analyzed by electron microprobe microscopy. Hall Effect measurements were conducted to determine the electrical conductivity, mobility and carrier concentration. In addition, Seebeck voltage and thermal conductivity measurements were performed. The thermoelectric properties are presented anddiscussed as a function of temperature up to 1273 K. The thermal stability of the primary CoP3 was examined in a static vacuum under isothermal and in-gradient conditions. The effect of the presence of 1 atm of a cover gas on the material loss rate was analyzed.

thermoelectric↗
NASA NTRS2010

Global Hawk Pacific (GloPac) COA and Mission Coordination

This slide presentation reviews the science objectives of the Global Hawk unmanned aircraft system (UAS) in the Pacific region, shows examp le flight tracks, the satellite under-flight requirement, the flight planning, and the agencies coordination of the airspace required for the Certificate of Authorization (COA).

Dillon, Mark↗
NASA NTRS2018

UAS-NAS NASA 870 Ikhana UAS No Chase COA (NCC) Flights, Flight Test Report

This document is a flight test report from the operational perspective for the No Chase Certificate of Waiver or Authorization (COA) flights, or NCC flights, a major milestone of the Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) project. Discussions of a demonstration event began as early as 2014 and the actual flight of the Ikhana UAS into the NAS without a safety chase vehicle in Class A, E, and D airspace was accomplished on 12 June, 2018. The major goal of this flight was to demonstrate an alternate means of compliance to the see and avoid regulations for a UAS using Detect and Avoid (DAA) technology. Participants in this flight activity and planning included the National Aeronautics and Space Administration (NASA) Ames Research Center, NASA Armstrong Flight Research Center, General Atomics Aeronautical Systems, Inc. (GA-ASI), Honeywell International, Inc., and the Federal Aviation Administration (FAA).

Marston, Mike↗
DOE OSTI2020

Materials Data on Ba(CoAs)2 by Materials Project

BaCo2As2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. All Ba–As bond lengths are 3.43 Å. Co2+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing CoAs4 tetrahedra. All Co–As bond lengths are 2.33 Å. As3- is bonded in a 8-coordinate geometry to four equivalent Ba2+ and four equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La(CoAs)2 by Materials Project

LaCo2As2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. La3+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. All La–As bond lengths are 3.22 Å. Co+1.50+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing CoAs4 tetrahedra. All Co–As bond lengths are 2.35 Å. As3- is bonded in a 9-coordinate geometry to four equivalent La3+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(CoAs)2 by Materials Project

EuCo2As2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. All Eu–As bond lengths are 3.20 Å. Co2+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing CoAs4 tetrahedra. All Co–As bond lengths are 2.33 Å. As3- is bonded in a 4-coordinate geometry to four equivalent Eu2+ and four equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

In Situ Synthesis of Graphene-Coated Silicon Monoxide Anodes from Coa-Derived Humic Acid for High-Performance Lithium-Ion Batteries

Silicon monoxide (SiO) is attaining extensive interest amongst silicon-based materials due to its high capacity and long cycle life; however, its low intrinsic electrical conductivity and poor coulombic efficiency strictly limit its commercial applications. Here low-cost coal-derived humic acid (HA) is used as a feedstock to synthesize in-situ graphene-coated disproportionated SiO (D-SiO@G) anode with a facile method. HRTEM and XRD confirm the well-coated graphene layers on an SiO surface. Scanning Transmission X-ray Microscopy (STXM) and X-ray Absorption Near-Edge Structure (XANES) spectra analysis indicate that the graphene coating effectively hinders the side-reactions between the electrolyte and SiO particles . As a result, the D-SiO@G anode presents an initial discharge capacity of 1937.6 mAh g -1 at 0.1 A g -1 and an initial coulombic efficiency (ICE) of 78.2%. High reversible capacity (1023 mAh g -1 at 2.0 A g -1 ), excellent cycling performance ( 72.4% capacity retention after 500 cycles at 2.0 A g -1 ), and rate capability (774 mAh g -1 at 5 A g -1 ) results are substantial. Full coin cells assembled with LiFePO 4 electrodes and D-SiO@G electrodes display impressive rate performance. These results indicate a promising potential for practical use in high-performance lithium-ion batteries.

25 ENERGY STORAGE↗