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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.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Chiral Determination of Amino Acids Using X-Ray Diffraction of Thin Films

The astrobiological search for life, both extinct and extant, on other solar system bodies will take place via several planned lander missions to Mars Europa and Titan. The detection and identification of organic molecules that have been associated with life is a major technical challenge. Terrestrial life utilizes organic molecules, such as amino acids, as its basic building block. Amino acids can be synthesized by natural processes as is demonstrated by their detection in meteoritic material. In this process, the organic molecules are produced roughly in a even mixture of D and L forms. Biological process, however, can utilize almost uniquely one form or the other. In terrestrial biology, only the L-amino acids is common in biological processes. If signature of life existed elsewhere in the D form it then be concluded that life had evolutionary beginning on that body. Detection of an enantiomeric excess of L over D would also be a powerful sign that life had existed on that body at one time.

D Dragoi↗
DOE OSTI2024

Evaluation of Apparent Metabolizable Energy and Apparent Ileal Amino Acid Digestibility of Spirulina (Arthrospira platensis) in Broiler Chickens and Laying Hens

Our study objective was to determine the apparent metabolizable energy (AME) and apparent ileal amino acid digestibility (AIAAD) of spirulina fed to broiler chickens and laying hens using the difference method. In both experiments, birds were either fed corn-soybean meal basal diets, containing no spirulina and formulated to provide the nutrient requirements of either broilers or layers, or fed test diets consisting of 25% spirulina and 75% of the appropriate basal diet. Titanium dioxide was added to all diets as an indigestible marker. The diets were fed to 10 replicate cages/treatment of broilers and 15 replicate cages/treatment of laying hens. The AME of spirulina for broilers was significantly lower (p < 0.05) (2368 ± 104 kcal/kg, as fed) than for laying hens (3144 ± 173 kcal/kg, as fed), suggesting bird type and age may influence energy utilization. The AIAAD of spirulina fed to broiler chickens did not differ from that of laying hens (p > 0.05), except for valine, alanine, and glycine, which were all significantly higher in laying hens (p < 0.05). Overall, the AIAAD for nonessential amino acids averaged 81.1%, with no significant difference between essential and nonessential amino acids. Differences in spirulina nutrient content cited in the literature support further research to determine the optimal inclusion of this alternative ingredient in broiler and layer diets.

Agriculture↗
NASA NTRS1976

Amino acid precursors in lunar fines - Limits to the contribution of jet exhaust

A sample of lunar fines collected at a maximum distance, 6.5 km, from the descent engine on Apollo 17 has been analyzed for total amino acids obtainable by hydrolysis of aqueous extracts. The minimum amounts of amino acids, calculated for a disk of 6 km radius are 10,000 to 100,000 times those which could be contributed by the lunar module jet exhaust, on the basis of conservatively limiting assumptions. The amino acids thus obtained are not explainable as due to chemical or biological contamination; their source is accordingly inferred as lunar. Under the conditions of hydrolysis of lunar extracts, cyanide is found to be converted, almost exclusively to glycine, to an extent of 0.0001.

Fox, S. W.↗
NASA NTRS2001

The sugar model: catalysis by amines and amino acid products

Ammonia and amines (including amino acids) were shown to catalyze the formation of sugars from formaldehyde and glycolaldehyde, and the subsequent conversion of sugars to carbonylcontaining products under the conditions studied (pH 5.5 and 50 degrees C). Sterically unhindered primary amines were better catalysts than ammonia, secondary amines, and sterically hindered primary amines (i.e. alpha-aminoisobutyric acid). Reactions catalyzed by primary amines initially consumed formaldehyde and glycolaldehyde about 15-20 times faster than an uncatalyzed control reaction. The amine-catalyzed reactions yielded aldotriose (glyceraldehyde), ketotriose (dihydroxyacetone), aldotetroses (erythrose and threose), ketotetrose (erythrulose), pyruvaldehyde, acetaldehyde, glyoxal, pyruvate, glyoxylate, and several unindentified carbonyl products. The concentrations of the carbonyl products, except pyruvate and ketotetrose, initially increased and then declined during the reaction, indicating their ultimate conversion to other products (like larger sugars or pyruvate). The uncatalyzed control reaction yielded no pyruvate or glyoxylate, and only trace amounts of pyruvaldehyde, acetaldehyde and glyoxal. In the presence of 15 mM catalytic primary amine, such as alanine, the rates of triose and pyruvaldehyde of synthesis were about 15-times and 1200-times faster, respectively, than the uncatalyzed reaction. Since previous studies established that alanine is synthesized from glycolaldehyde and formaldehyde via pyruvaldehyde as its direct precursor, the demonstration that the alanine catalyzes the conversion of glycolaldehyde and formaldehyde to pyruvaldehyde indicates that this synthetic pathway is capable of autocatalysis. The relevance of this synthetic process, named the Sugar Model, to the origin of life is discussed.

Acetaldehyde/analogs & derivatives/chemistry↗
NASA NTRS1994

The Strecker synthesis from interstellar precursors as a source of amino acids in carbonaceous chondrites: Deuterium retention during synthesis

Amino acids in the Murchison carbonaceous chondrite are anomalously enriched in deuterium. Synthesis in Strecker reactions from D-enriched interstellar precursors during low temperature aqueous alteration of the parent body has been proposed by Cronin et al. (1988) to account for the isotopic observations. To test this hypothesis, we have measured the retention of deuterium in the glycine, alanine, and alpha-amino isobutyric acid produced, respectively, by reactions of formaldehyde-D2, acetaldehyde-D4, and acetone-D6 with HCN and NH3 in water.

Lerner, N. R.↗
NASA NTRS1978

HCN - A plausible source of purines, pyrimidines and amino acids on the primitive earth

Dilute (0.1 M) solutions of HCN condense to oligomers at pH 9.2, and hydrolysis of these oligomers yields 4,5-dihydroxypyrimidine, orotic acid, 5-hydroxyuracil, adenine, 4-aminoimidazole-5-carboxamide, and amino acids. It is suggested that the three main classes of nitrogen-containing biomolecules - purines, pyrimidines, and amino acids may have originated from HCN on the primitive earth. It is also suggested that the presence of orotic acid and 4-aminoimidazole-5-carboxamide might indicate that contemporary biosynthetic pathways for nucleotides evolved from the compounds released on hydrolysis of HCN oligomers.

Ferris, J.-P.↗
DOE OSTI2024

Carbon Negative Synthesis of Amino Acids Using a Cell-Free-Based Biocatalyst

Biological systems can directly upgrade carbon dioxide (CO 2 ) into chemicals. The CO 2 fixation rate of autotrophic organisms, however, is too slow for industrial utility, and the breadth of engineered metabolic pathways for the synthesis of value-added chemicals is too limited. Biotechnology workhorse organisms with extensively engineered metabolic pathways have recently been engineered for CO 2 fixation. Yet, their low carbon fixation rate, compounded by the fact that living organisms split their carbon between cell growth and chemical synthesis, has led to only cell growth with no chemical synthesis achieved to date. Here, we engineer a lysate-based cell-free expression (CFE)-based multienzyme biocatalyst for the carbon negative synthesis of the industrially relevant amino acids glycine and serine from CO 2 equivalents–formate and bicarbonate–and ammonia. The formate-to-serine biocatalyst leverages tetrahydrofolate (THF)-dependent formate fixation, reductive glycine synthesis, serine synthesis, and phosphite dehydrogenase-dependent NAD(P)H regeneration to convert 30% of formate into serine and glycine, surpassing the previous 22% conversion using a purified enzyme system. We find that (1) the CFE-based biocatalyst is active even after 200-fold dilution, enabling higher substrate loading and product synthesis without incurring additional cell lysate cost, (2) NAD(P)H regeneration is pivotal to driving forward reactions close to thermodynamic equilibrium, (3) balancing the ratio of the formate-to-serine pathway genes added to the CFE is key to improving amino acid synthesis, and (4) efficient THF recycling enables lowering the loading of this cofactor, reducing the cost of the CFE-based biocatalyst. To our knowledge, this is the first synthesis of amino acids that can capture CO 2 equivalents for the carbon negative synthesis of amino acids using a CFE-based biocatalyst. Looking ahead, the CFE-based biocatalyst process could be extended beyond serine to pyruvate, a key intermediate, to access a variety of chemicals from aromatics and terpenes to alcohols and polymers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Meal composition and plasma amino acid ratios: Effect of various proteins or carbohydrates, and of various protein concentrations

The effects of meals containing various proteins and carbohydrates, and of those containing various proportions of protein (0 percent to 20 percent of a meal, by weight) or of carbohydrate (0 percent to 75 percent), on plasma levels of certain large neutral amino acids (LNAA) in rats previously fasted for 19 hours were examined. Also the plasma tryptophan ratios (the ratio of the plasma trytophan concentration to the summed concentrations of the other large neutral amino acids) and other plasma amino acid ratios were calculated. (The plasma tryptophan ratio has been shown to determine brain tryptophan levels and, thereby, to affect the synthesis and release of the neurotransmitter serotonin). A meal containing 70 percent to 75 percent of an insulin-secreting carbohydrate (dextrose or dextrin) increased plasma insulin levels and the tryptophan ratio; those containing 0 percent or 25 percent carbohydrate failed to do so. Addition of as little as 5 percent casein to a 70 percent carbohydrate meal fully blocked the increase in the plasma tryptophan ratio without affecting the secretion of insulin - probably by contributing much larger quantities of the other LNAA than of tryptophan to the blood. Dietary proteins differed in their ability to suppress the carbohydrate-induced rise in the plasma tryptophan ratio. Addition of 10 percent casein, peanut meal, or gelatin fully blocked this increase, but lactalbumin failed to do so, and egg white did so only partially. (Consumption of the 10 percent gelatin meal also produced a major reduction in the plasma tyrosine ratio, and may thereby have affected brain tyrosine levels and catecholamine synthesis.) These observations suggest that serotonin-releasing neurons in brains of fasted rats are capable of distinguishing (by their metabolic effects) between meals poor in protein but rich in carbohydrates that elicit insulin secretion, and all other meals. The changes in brain serotonin caused by carbohydrate-rich, protein-poor meals may affect subsequent food choice and various serotonin-mediated behaviors.

Yokogoshi, Hidehiko↗
NASA NTRS1972

Amino acid precursors in lunar samples.

The use of hot water to extract lunar samples, followed by the hydrolysis of the aqueous extract, appears to be the method of choice for identification and quantitation of amino acid precursors in extraterrestrial sources. The net inferences from the analyses to date are (1) that amino acid precursors are verifiably present in lunar dust, and (2) that they are quite certainly not the consequence of contamination by terrestrial organisms, including man. It is suggested that prebiotic evolutionary pathways such as have been traversed on the earth were terminated on the moon for lack of sufficient water. Although some or all of the amino acid precursors may be indigenous, the low level observed suggests that they may also result from onfall of organic compounds from interstellar matter, comets, tails, solar wind, or meteorites.

Fox, S. W.↗
NASA NTRS1989

Metabolism of branched-chain amino acids in leg muscles from tail-cast suspended intact and adrenalectomized rats

The effects of muscle unloading, adrenalectomy, and cortisol treatment on the metabolism of branched-chain amino acids in the soleus and extensor digitorum longus of tail-cast suspended rats were investigated using C-14-labeled lucine, isoleucine, and valine in incubation studies. It was found that, compared to not suspended controls, the degradation of branched-chain amino acids in hind limb muscles was accelerated in tail-cast suspended rats. Adrenalectomy was found to abolish the aminotransferase flux and to diminish the dehydrogenase flux in the soleus. The data also suggest that cortisol treatment increases the rate of metabolism of branched-chain amino acids at the dehydrogenase step.

Jaspers, Stephen R.↗
NASA NTRS1988

The polymerization of amino acid adenylates on sodium-montmorillonite with preadsorbed polypeptides

The spontaneous polymerization of amino acid adenylates on Na-montmorillonite in dilute, neutral suspension, after polypeptides were adsorbed on the clay, is studied. It is found that the degrees of polymerization of the oligopeptides and polypeptides obtained is dependent on the amounts of polypeptides that were preadsorbed. It is concluded that a catalytic activity may derive from c-spacings that offer adsorption sites for the reagent amino acid adenylate within the peripheral recesses of irregularly stacked clay platelets by bringing the anhydride bonds and neutral amino groups into favorable reaction distances.

Paecht-Horowitz, Mella↗
NASA NTRS1981

Search for effect of longitudinally polarized protons on optically active amino acids

The influence of irradiation by longitudinally polarized protons on the differential decomposition of amino acid is investigated in a test of the Vester Ulbricht hypothesis that L-amino acids were produced in preference to the D isomers on the primitive earth due to the effects of parity violation in beta decay. Samples of DL-leucine were irradiated with protons of both positive and negative longitudinal polarization, then analyzed by gas chromatography. Despite advantages of higher polarization, lower velocity and higher ionization density of protons with respect to electrons, proton irradation is found to lead to no detectable asymmetries in DL-leucine degradation, even at 50% gross degradation.

Lemmon, R. M.↗
NASA NTRS1998

A search for endogenous amino acids in martian meteorite ALH84001

Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the L enantiomer, low concentrations (<0.1 parts per million) of endogenous D-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as D-alanine are preserved in the meteorite.

NASA Discipline Exobiology↗