A 19F nuclear magnetic resonance study of the interaction of carbon dioxide with fluoro-amino acids

1985 ◽  
Vol 63 (10) ◽  
pp. 1120-1126 ◽  
Author(s):  
Heather D. Dettman ◽  
Joel H. Weiner ◽  
Brian D. Sykes

The 19F nuclear magnetic resonance (NMR) spectra of 3-fiuorophenylalanine and 3-fluorotyrosine in bicarbonate buffer are characterized by a main resonance band and a well-resolved upfield resonance. We show that the upfield resonance is due to the formation of a carbamate between the amino group of the amino acid and bicarbonate. The intensity of the upfield resonance is dependent on the pH (pD) of the solution and reflects changes in the concentration of the free amino acid and carbamate. Thus the normalized spectral peaks can be used to quantitate the free amino acid and carbamate concentrations and these concentrations have been used to determine the equilibrium constant of the carbamate reaction. The value of the equilibrium constant obtained, using an equation which considered the various ionic states of the reactants, was 8.52 × 10−6 ± 0.27 × 10−6 for 3-fiuorophenylalanine and 8.84 × 10−6 ± 0.72 × 10−6 for 3-fluorotyrosine. These values are within the range expected for amino acids and indicate that the fluorine nucleus does not perturb the reaction significantly and that the 19F NMR can be used to quantitate the formation of carbamates in solutions of fluorine-labelled amino acids.

1977 ◽  
Vol 55 (4) ◽  
pp. 439-444 ◽  
Author(s):  
Kathleen D. Chance ◽  
Donald G. Clark

The in vivo incorporation of L-[Me-3H]methionine into egg white lysozyme of the laying hen has been examined. Using a versatile synthetic chicken diet which consisted of 75% free amino acid ration and 25% normal laying ration, a 5–8% incoiporation of the [3H]methionine into lysozyme was demonstrated. The utility of this vertebrate in vivo incorporation technique is discussed in terms of its application to the incorporation of 13C-enriched amino acids into vertebrate proteins as a prelude to macromolecular 13C nuclear magnetic resonance studies.


2021 ◽  
Author(s):  
Mizuki Watanabe ◽  
Makoto Nagata ◽  
Ryohei Doi ◽  
Mai Uemura ◽  
Nanase Ochiai ◽  
...  

Considerable effort has been directed toward developing artificial peptide-based oligomers that fold into a specific secondary structure, i.e., peptide foldamers. To date, however, detailed structural analysis of crystals of δ-peptide foldamers consisting of aliphatic δ-amino acids, which have a more extended carbon backbone compared with well-studied β- and γ-amino acids, have not been reported. We rationally designed aliphatic homo-δ-peptide foldamers forming a stable helical structure utilizing a chiral cyclopropane δ-amino acid as a monomer unit whose conformation was tightly restricted by the structural characteristics of cyclopropane depending on its stereochemistry. We stereoselectively synthesized the cyclopropane δ-amino acid monomer and prepared its various homo-oligomers. Structural analysis of the homo-δ-peptides using nuclear magnetic resonance, circular dichroism, and infrared spectroscopy revealed that they form a stable 14-helical structure in solution. Furthermore, the effective conformational regulation of the backbone due to the characteristics of cyclopropane allowed us to achieve X-ray crystallographic analysis of the homo-δ-peptides, showing their common right-handed 14-helical structures. The helical structures were consistent with both those predicted by theoretical calculations and those obtained based on nuclear magnetic resonance spectroscopy in solution. A critical point is that the helical structures of these δ-peptides are theoretically predictable by calculations. To our knowledge, this is the first example of aliphatic homo-δ-peptide foldamers forming a stable helical structure both in solution and in crystal.


2020 ◽  
Vol 22 (9) ◽  
pp. 657-662 ◽  
Author(s):  
Mustafa Celik ◽  
Alper Şen ◽  
İsmail Koyuncu ◽  
Ataman Gönel

Aim and Objective:: To determine the mechanisms present in the etiopathogenesis of nasal polyposis. It is not clear whether amino acids contribute in a causal way to the development of the disease. Therefore, the aim of this study was to determine the plasma-free amino acid profile in patients with nasal polyposis and to compare the results with a healthy control group. Materials and Methods:: This was a prospective controlled study that took place in the Otolaryngology Department at the Harran University Faculty of Medicine between April 2017 and April 2018. Plasmafree amino acid profile levels were studied in serum samples taken from a patient group and a healthy control group. Patients who were diagnosed with bilateral diffuse nasal polyposis and were scheduled for surgical interventions were included in this study. Individuals whose age, gender, and body mass index values were compatible with that of the patient group and who did not have any health problems were included in the control group. All the participants whose levels of plasma-free amino acid were thought to be affected by one or more of the following factors were excluded from the study: smoking and alcohol use, allergic rhinitis presence, the presence of acute or chronic sinusitis, a history of endoscopic sinus surgery, unilateral nasal masses, a history of chronic drug use, systemic or topical steroid use in the last three months for any reason, and liver, kidney, hematological, cardiovascular, metabolic, neurological, or psychiatric disorders or malignancies. Results: In patients with nasal polyposis, 3-methyl histidine (3-MHIS: nasal polyposis group (ng) = 3.22 (1.92 – 6.07); control group (cg) = 1.21 (0.77 – 1.68); p = 0.001); arginine (arg: ng = 98.95 (70.81 – 117.75); cg = 75.10 (54.49 – 79.88); p = 0.005); asparagine (asn: ng = 79.84 (57.50 – 101.44); cg = 60.66 (46.39 – 74.62); p = 0.021); citrulline (cit: ng = 51.83 (43.81 – 59.78); cg = 38.33 (27.81 – 53.73); p = 0.038); cystine (cys: ng = 4.29 (2.43 – 6.66); cg = 2.41 (1.51 – 4.16); p = 0.019); glutamic acid (glu: ng = 234.86 (128.75 – 286.66); cg = 152.37 (122.51 – 188.34); p = 0.045); histidine (his: ng = 94.19 (79.34 – 113.99); cg = 74.80 (62.76 – 98.91); p = 0.018); lysine (lys: ng = 297.22 (206.55 – 371.25); cg = 179.50 (151.58 – 238.02); p = 0.001); ornithine (ng = 160.62 (128.36 – 189.32); cg = 115.91 (97.03 – 159.91); p = 0.019); serine (ser: ng = 195.15 (151.58 – 253.07); cg = 83.07 (67.44 – 92.44); p = 0.001); taurine (tau: ng = 74.69 (47.00 – 112.13); cg = 53.14 (33.57 – 67.31); p = 0.006); tryptophan (trp: ng = 52.31 (33.81 – 80.11); cg = 34.44 (25.94 – 43.07); p = 0.005), homocitrulline (ng = 1.75 (1.27 – 2.59); cg = 0.00 (0.00 – 0.53); p = 0.001); norvaline (ng = 6.90 (5.61 – 9.18); cg = 4.93 (3.74 – 7.13); p = 0.021); argininosuccinic acid (ng = 14.33 (10.06 – 25.65); cg = 12.22 (5.77 – 16.87) p = 0.046); and plasma concentrations were significantly higher than in the healthy control group (p <0.05). However, the gamma-aminobutyric acid (gaba: ng = 0.16 (0.10 – 0.24); cg = 0.21 (0.19 – 0.29); p = 0.010) plasma concentration was significantly lower in the nasal polyposis group than in the healthy control group. Conclusion: In this study, plasma levels of 15 free amino acids were significantly higher in the nasal polyposis group than in the healthy control group. A plasma level of 1 free amino acid was found to be significantly lower in the nasal polyposis group compared to the healthy control group. Therefore, it is important to determine the possibility of using the information obtained to prevent the recurrence of the condition and to develop effective treatment strategies. This study may be a milestone for studies of this subject. However, this study needs to be confirmed by further studies conducted in a larger series.


1973 ◽  
Vol 248 (17) ◽  
pp. 6104-6113 ◽  
Author(s):  
Philip Keim ◽  
Robert A. Vigna ◽  
Robert C. Marshall ◽  
Frank R.N. Gurd

2021 ◽  
Vol 19 (1) ◽  
pp. 35-43
Author(s):  
Awatsaya Chotekajorn ◽  
Takuyu Hashiguchi ◽  
Masatsugu Hashiguchi ◽  
Hidenori Tanaka ◽  
Ryo Akashi

AbstractWild soybean (Glycine soja) is a valuable genetic resource for soybean improvement. Seed composition profiles provide beneficial information for the effective conservation and utilization of wild soybeans. Therefore, this study aimed to assess the variation in free amino acid abundance in the seeds of wild soybean germplasm collected in Japan. The free amino acid content in the seeds from 316 accessions of wild soybean ranged from 0.965 to 5.987 mg/g seed dry weight (DW), representing a 6.2-fold difference. Three amino acids had the highest coefficient of variation (CV): asparagine (1.15), histidine (0.95) and glutamine (0.94). Arginine (0.775 mg/g DW) was the predominant amino acid in wild soybean seeds, whereas the least abundant seed amino acid was glutamine (0.008 mg/g DW). A correlation network revealed significant positive relationships among most amino acids. Wild soybean seeds from different regions of origin had significantly different levels of several amino acids. In addition, a significant correlation between latitude and longitude of the collection sites and the total free amino acid content of seeds was observed. Our study reports diverse phenotypic data on the free amino acid content in seeds of wild soybean resources collected from throughout Japan. This information will be useful in conservation programmes for Japanese wild soybean and for the selection of accessions with favourable characteristics in future legume crop improvement efforts.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jing Fan ◽  
Jing Hong ◽  
Jun-Duo Hu ◽  
Jin-Lian Chen

Aim. Amino acid metabolism in cancer patients differs from that in healthy people. In the study, we performed urine-free amino acid profile of gastric cancer at different stages and health subjects to explore potential biomarkers for diagnosing or screening gastric cancer.Methods. Forty three urine samples were collected from inpatients and healthy adults who were divided into 4 groups. Healthy adults were in group A (n=15), early gastric cancer inpatients in group B (n=7), and advanced gastric cancer inpatients in group C (n=16); in addition, two healthy adults and three advanced gastric cancer inpatients were in group D (n=5) to test models. We performed urine amino acids profile of each group by applying ion chromatography (IC) technique and analyzed urine amino acids according to chromatogram of amino acids standard solution. The data we obtained were processed with statistical analysis. A diagnostic model was constructed to discriminate gastric cancer from healthy individuals and another diagnostic model for clinical staging by principal component analysis. Differentiation performance was validated by the area under the curve (AUC) of receiver-operating characteristic (ROC) curves.Results. The urine-free amino acid profile of gastric cancer patients changed to a certain degree compared with that of healthy adults. Compared with healthy adult group, the levels of valine, isoleucine, and leucine increased (P<0.05), but the levels of histidine and methionine decreased (P<0.05), and aspartate decreased significantly (P<0.01). The urine amino acid profile was also different between early and advanced gastric cancer groups. Compared with early gastric cancer, the levels of isoleucine and valine decreased in advanced gastric cancer (P<0.05). A diagnosis model constructed for gastric cancer with AUC value of 0.936 tested by group D showed that 4 samples could coincide with it. Another diagnosis model for clinical staging with an AUC value of 0.902 tested by 3 advanced gastric cancer inpatients of group D showed that all could coincide with the model.Conclusions. The noticeable differences of urine-free amino acid profiles between gastric cancer patients and healthy adults indicate that such amino acids as valine, isoleucine, leucine, methionine, histidine and aspartate are important metabolites in cell multiplication and gene expression during tumor growth and metastatic process. The study suggests that urine-free amino acid profiling is of potential value for screening or diagnosing gastric cancer.


1980 ◽  
Vol 239 (6) ◽  
pp. G493-G496 ◽  
Author(s):  
E. J. Feldman ◽  
M. I. Grossman

Using intragastric titration in dogs with gastric fistulas, dose-response studies were carried out with liver extract and with a mixture of amino acids that matched the free amino acids found in liver extract. All solutions were adjusted to pH 7.0 and osmolality to 290 mosmol x kg-1. Doses are expressed as the sum of the concentrations of all free amino acids. At each dose studied (free amino acid concentration: 2.8, 5.6, 11, 23, and 45 mM), acid secretion in response to the free amino acid mixture was not significantly different from that of liver extract. The peak response to both liver extract and the free amino acid mixture occurred with the 23-mM dose and represented about 60% of the maximal response to histamine. The serum concentrations of gastrin after liver extract and the amino acid mixture were not significantly different. It is concluded that in dogs with gastric fistula, gastric acid secretion and release of gastrin were not significantly different in response to liver extract and to a mixture of amino acids that simulated the free amino acid content of liver extract.


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