Use of N-Carboxyanhydrides in the Synthesis of Dipeptides. Factors Affecting the Yields of Several Alanine and Valine-containing Dipeptides

1973 ◽  
Vol 51 (8) ◽  
pp. 1284-1287 ◽  
Author(s):  
Eric M. Grovestine ◽  
Jean R. Langlois ◽  
Ross E. Williams
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
Side Chains ◽  
Organic Base ◽  
Factors Affecting ◽  
The Stability

A series of dipeptides having aliphatic side chains have been prepared in aqueous solution from alanine and valine NCA. An organic base was used to establish and maintain the pH. After the reaction the amounts of unreacted amino acid nucleophile and the overall yields in the reaction were determined. Our observations have led us to propose that NCA stability, the pKa of the amino acid nucleophile and the stability of the carbamate all can play an important role in determining synthetic yields during these preparations.

Complexation of Fluorinated Amino Acid Derivatives by β- and γ-Cyclodextrin in Aqueous Solution. A 19F Nuclear Magnetic Resonance Study

1995 ◽  
Vol 48 (3) ◽  
pp. 505 ◽  
Author(s):  
SE Brown ◽  
CJ Easton ◽  
SF Lincoln
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Amino Acid Derivatives ◽  
Magnetic Resonance Study ◽  
Cyclodextrin Complexes ◽  
Factors Affecting ◽  
Chemical Shift Data ◽  
Shift Data ◽  
Insight Into

A 19F n.m.r. study shows that the β-cyclodextrin complexes of deprotonated α-(p- fluorophenyl ) glycine, N-acetyl-α-(p- fluorophenyl ) glycine , deprotonated N-acetyl-α-(p- fluorophenyl ) glycine , and N-(p- fluorobenzoyl ) valine are characterized by stability constants KR/dm3 mol-1 and Ks/dm3 mol-1 =13�2 and 21�3, 34�1 and 35�2, 12�1 and 12� 1, and 84�2 and 93�2, respectively, where the first and second of each pair of values refers to the complex formed by the R and S enantiomers of the fluorinated amino acid derivatives, respectively, in 10% aqueous D2O solution at 295.5 K and I = 0.10 mol dm-3. A comparison of these data and the associated 19F chemical shift data with those for the analogous α- and γ- cyclodextrin complexes provides an insight into the factors affecting the stabilities and structures of these complexes.

Role of charged amino acid side chains in the stability and lipid binding ofManduca sexta apolipophorin III

1995 ◽  
Vol 30 (2-3) ◽  
pp. 211-223 ◽  
Author(s):  
Minal Upadhyaya ◽  
Kim Oikawa ◽  
Cyril M. Kay ◽  
Douglas G. Scraba ◽  
Roger Bradley ◽  
...  
Keyword(s):  
Amino Acid ◽  
Lipid Binding ◽  
Side Chains ◽  
Apolipophorin Iii ◽  
Amino Acid Side Chains ◽  
The Stability

Glutamine stability in biological tissues evaluated by fluorometric analysis

1993 ◽  
Vol 39 (6) ◽  
pp. 1059-1063 ◽  
Author(s):  
V B Grossie ◽  
J Yick ◽  
M Alpeter ◽  
T C Welbourne ◽  
D M Ota
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
High Efficiency ◽  
Biological Tissues ◽  
Measured Concentration ◽  
Important Amino Acid ◽  
Tissue Extracts ◽  
Normal Rat ◽  
Fluorometric Analysis ◽  
The Stability

Abstract Although glutamine has been considered unstable during storage and therefore difficult to quantitate, recent results suggest this amino acid is stable at low pH ranges. We evaluated the stability of glutamine in plasma and tissue extracts, using fluorometric analysis. The measured concentration of glutamine detected varied linearly up to 0.8 mmol/L for the aqueous solution (r2 = 98.7, P = 0.0001) with a mean (+/- SD) coefficient of variation of 2.41% +/- 0.79%. When glutamine was dissolved in 50 g/L trichloroacetic acid (TCA), the values were essentially unaltered. Glutamine in an aqueous solution and stored at -70 degrees C was stable for at least 16 days; glutamine in TCA was stable for 6-8 days, then decreased to a concentration significantly lower than that of the aqueous solution. The expected and observed concentrations in plasma were equal (r2 = 0.99975) for increasing amounts of added glutamine. Glutamine concentrations in plasma were stable for > 1 year when stored at -70 degrees C. The glutamine of a transplantable rat sarcoma and a normal rat liver could be extracted with 50 g/L TCA with high efficiency (88.6% +/- 1.9% and 90.2% +/- 0.04%, respectively); the extracted glutamine is stable in TCA for at least 7 days without neutralization when stored at -70 degrees C. Fluorometric analysis of glutamine required only a small quantity of plasma (25 microL) or tissue (200 mg) and is a convenient method for quantifying this important amino acid.

The Stability and Structure of Complex Species Formed in Equilibrium Reactions of Diethyltin(IV) with N-D-Gluconylamino Acids in Aqueous Solution

1995 ◽  
Vol 50 (4) ◽  
pp. 515-523 ◽  
Author(s):  
B. Gyurcsik ◽  
N. Buzás ◽  
T. Gajda ◽  
L. Nagy ◽  
E. Kuzmann ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
Water Soluble ◽  
Complex Formation Equilibria ◽  
Complex Species ◽  
Carboxylate Oxygen ◽  
Equilibrium Reactions ◽  
Formation Equilibria ◽  
The Stability ◽  
Ph Range

Complex formation equilibria of diethyltin(IV) with five N-D-gluconylamino acids in aqueous solution (I = 0.1 M, NaClO4) were studied and the stabilities of the species were determined by potentiometric titrations. Diethyltin(IV) complexes of α-amino acid derivatives are water-soluble in the physiological pH range, while in the presence of N-D-gluconyl-β-alanine a precipitate is formed, which dissolves with increasing pH. 13C NMR measurements showed that in the N-D-gluconyl-α-amino acid complexes the ligand is coordinated through its deprotonated carboxylate oxygen, amide nitrogen and C(2)-hydroxy group, while for the soluble N-D-gluconyl-β-alanine complex the ligand is coordinated via the deprotonated carboxylate and C(3)-, C(4)-, C(5)-hydroxy groups. Mössbauer measurements reflected the geometry of the complexes formed.

How non-bonding amino acid side-chains may enormously increase the stability of a Cu(II)—peptide complex

1998 ◽  
Vol 283 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Wojciech Bal ◽  
Marcin Dyba ◽  
Franciszek Kasprzykowski ◽  
Henryk Kozłowski ◽  
Rafał Latajka ◽  
...  
Keyword(s):  
Amino Acid ◽  
Side Chains ◽  
Peptide Complex ◽  
Amino Acid Side Chains ◽  
The Stability
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