Efficient, Racemization-Free Peptide Coupling of N-Alkyl Amino Acids by Using Amino Acid Chlorides Generated in situ — Total Syntheses of the Cyclopeptides Cyclosporin O and Omphalotin A.

ChemInform ◽  
2003 ◽  
Vol 34 (14) ◽  
Author(s):  
Norbert Sewald
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Chlorides ◽  
Total Syntheses ◽  
Peptide Coupling ◽  
Free Peptide

A facile one pot route for the synthesis of imide tethered peptidomimetics

2016 ◽  
Vol 14 (2) ◽  
pp. 556-563 ◽  
Author(s):  
Veladi Panduranga ◽  
Girish Prabhu ◽  
Roopesh Kumar ◽  
Basavaprabhu Basavaprabhu ◽  
Vommina V. Sureshbabu
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Efficient Method ◽  
One Pot ◽  
Protected Amino Acid

A simple and efficient method for the synthesis of N,N’-orthogonally protected imide tethered peptidomimetics is presented. The imide peptidomimetics were synthesized by coupling the in situ generated selenocarboxylate of Nα-protected amino acids with Nα-protected amino acid azides in good yields.

Uptake and metabolism of amino acids by the dog liver perfused in situ

1962 ◽  
Vol 202 (3) ◽  
pp. 407-414 ◽  
Author(s):  
Rapier H. McMenamy ◽  
William C. Shoemaker ◽  
Jonas E. Richmond ◽  
David Elwyn
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Sharp Rise ◽  
Dog Blood ◽  
Dog Liver ◽  
Amino Acid Concentrations ◽  
Uptake And Metabolism

Dog livers were perfused in situ for periods up to 6 hr with dog blood recycled through a pump-oxygenator. An amino acid mixture was administered for 90 min. Concentrations of amino acids were determined at intervals of 30 min or more. Rates of uptake and metabolism were calculated. After the start of perfusion, there is a fall in most plasma amino acid concentrations and a reciprocal rise in liver amino acids. Addition of amino acids causes a sharp rise in plasma amino acids. There is a rapid uptake of most of the amino acids by liver, although the concentrations of amino acids in liver fail to rise appreciably. Notable exceptions are valine, leucine, and isoleucine. Uptake of amino acids stimulates: a) an increase in the rate of synthesis of urea which ultimately accounts for 90% of the metabolized amino acids; b) a net synthesis of ornithine; and c) net noncatabolic metabolism of amino acids which may in part be protein synthesis. The results support the view that the liver temporarily stores a part of ingested amino acids as proteins, and subsequently makes them available to other organs.

Amino acid transport by juxtamedullary nephrons: distal reabsorption and recycling

1988 ◽  
Vol 255 (3) ◽  
pp. F397-F407 ◽  
Author(s):  
W. H. Dantzler ◽  
S. Silbernagl
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
Acidic Amino Acids ◽  
Vasa Recta ◽  
Collecting Ducts ◽  
Distal Site

Amino acid transport by juxtamedullary (JM) nephrons and its relationship to transport by superficial cortical (SC) nephrons and to function of vasa recta and collecting ducts were examined in vivo and in situ by free-flow micropuncture of Henle's loops, collecting ducts, and vasa recta and by continuous microinfusion of Henle's loops in exposed rat papillae. Fractional deliveries (FDs) of six neutral amino acids, two acidic amino acids, and taurine to tips of Henle's loops of JM nephrons could be substantially below those to early distal loops of SC nephrons, indicating that reabsorption before loop tips could be greater in JM than in SC nephrons. FDs to collecting ducts lower than to JM loop tips suggested reabsorption distal to loop tips. This was confirmed by continuous microinfusion of ascending limbs of Henle's loops. Distal site of reabsorption is unknown, but amino acids may move passively out of the thin ascending limb and be recycled into vasa recta and descending limb. Recycling of amino acids was supported by high FDs to tips of Henle's loops (sometimes greater than 1.0), higher concentrations in ascending than in descending vasa recta at same papilla level, and high mean concentrations in vasa recta.

Amino acid mediated mesopore formation in LTA zeolites

2016 ◽  
Vol 4 (6) ◽  
pp. 2305-2313 ◽  
Author(s):  
Zhuwen Chen ◽  
Jian Zhang ◽  
Bole Yu ◽  
Guangchao Zheng ◽  
Jing Zhao ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hydrogen Bonding ◽  
Amino Acid ◽  
Mesoporous Zeolites ◽  
Calcination Step ◽  
Self Assembled

Amino acids, self-assembledin situ viahydrogen bonding, have been used to synthesize mesoporous zeolites without a calcination step.

scholarly journals Rumen degradability and ileal digestibility of proteins and amino acids of feedstuffs for cows

2014 ◽  
Vol 83 (3) ◽  
pp. 225-231
Author(s):  
Iveta Maskaľová ◽  
Vladimír Vajda ◽  
Marek Krempaský ◽  
Lukáš Bujňák
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Crude Protein ◽  
Amino Acid Profile ◽  
Ileal Digestibility ◽  
Corn Gluten ◽  
Corn Gluten Feed ◽  
Gluten Feed

Knowledge of the profile of amino acids of the rumen-undegradable protein can help in the formulation of diets to provide amino acids that complement microbial protein as well as supply amino acids, which are most limiting for milk production. Three non-lactating cows fitted with rumen cannulas were used to determine the effect ofin siturumen degradation on crude protein and amino acid profile of rumen-undegraded protein of feedstuffs. The obtained values of rumen degradability of crude protein with significant difference (P< 0.001) between feeds ranged from 20.3 to 76.3% (mean 62.0 ± 17.9%) and values of total amino acids ranged from 30.9% in corn gluten meal to 83.8% in corn gluten feed (mean 67.5 ± 16.4%). Anin vitromodified 3-step method was used to determine intestinal digestibility. Intestinal digestibility of undegraded protein varied from 54.5 ± 1.4% in raw soybean to 95.2 ± 1.0% in corn gluten feed. The absorbable amino acid profile of rumen-undegraded protein for each feedstuff was compared with profiles of the original feedstuff and the rumen-exposed undegraded protein. Absorbable lysine (9.3 ± 1.1 g/kg of crude protein) was higher in products of soybean and sunflower cake. Corn gluten feed and meal supplied more absorbable methionine (3.6 ± 0.6 g/kg of crude protein). This study showed that the digestibility factor of crude protein and amino acid based onin situandin vitromethods for thermal treatment of protein feeds can be used in models to optimize the amino acid nutrition of dairy cows and expand knowledge about rumen degradability and ileal digestibility of amino acids in feedstuffs.

Synthesis of functionalized pyrazole derivatives by regioselective [3+2] cycloadditions of N-Boc-α-amino acid-derived ynones

2018 ◽  
Vol 73 (7) ◽  
pp. 467-480 ◽  
Author(s):  
Eva Pušavec Kirar ◽  
Uroš Grošelj ◽  
Amalija Golobič ◽  
Franc Požgan ◽  
Sebastijan Ričko ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Ring Opening ◽  
Pyrazole Derivatives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acid Catalyzed ◽  
Azomethine Imines

Abstract [3+2] cycloadditions of ynones derived from glycine and (S)-alanine and some other dipolarophiles with azomethine imines, nitrile oxides, diazoacetate, and azidoacetate were studied. The dipolarophiles were obtained from α-amino acids, either by the reduction of the carboxy function with ethynylmagnesium bromide or by propiolation of the amino function. Cu-catalyzed cycloadditions of ynones to azomethine imines were regioselective and gave the expected cycloadducts as inseparable mixtures of diastereomers. In some instances, further oxidative hydrolytic ring-opening took place to afford 3,3-dimethyl-3-(1H-pyrazol-1-yl)propanoic acids. Acid-catalyzed cycloadditions of 3-butenone were also regioselective and provided mixtures of diastereomeric cycloadducts, which were separated by chromatography. In the reactions of title ynones with alkyl diazoacetates, in situ-formed benzonitrile oxides, and tert-butyl azidoacetate, all cycloadducts were obtained as single regioisomers. The structures of all novel compounds were established by nuclear magnetic resonance and X-ray diffraction.

Deprotection of N-Alloc amines by Pd(0)/DABCO—an efficient method for in situ peptide coupling of labile amino acids

2001 ◽  
Vol 42 (40) ◽  
pp. 7049-7053 ◽  
Author(s):  
Chiara Zorn ◽  
Frieder Gnad ◽  
Sunnhild Salmen ◽  
Timothy Herpin ◽  
Oliver Reiser
Keyword(s):  
Amino Acids ◽  
Efficient Method ◽  
Peptide Coupling
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