Use of Pd/sepiolite systems as hydrogenation catalysts. II. Hydrogenolysis of N-blocked amino acids and dipeptides by hydrogen transfer

1987 ◽  
Vol 65 (12) ◽  
pp. 2791-2797 ◽  
Author(s):  
A. Aramendia ◽  
V. Borau ◽  
C. Jimenez ◽  
J. M. Marinas ◽  
M. E. Sempere
Keyword(s):  
Amino Acids ◽  
Palladium Catalysts ◽  
Hydrogen Transfer ◽  
Hydrogen Donor ◽  
Amino Groups ◽  
Promoting Effect ◽  
Hydrogenation Catalysts ◽  
Ultrasonic Agitation

We have carried out the deprotecting of various N-protected amino acids and dipeptides by subjecting them to hydrogen transfer with several palladium catalysts supported on different solids. The hydrogen donor itself has been used "insitu" to reduce the corresponding Pd salt on the support. We have also analyzed the effect of various factors on the deprotecting rate for Z-glycine. Such factors include the procedure used in synthesizing the catalysts ("insitu" or by conventional reduction), the type of support, hydrogen donor, promoting effect of alkaline hydroxides, type of reactor (closed or open), and magnetic or ultrasonic agitation. We have found that the ease of adsorption of the protected amino groups (Z—NH—) is fundamental in accounting for the order of deprotecting rates found. We have compared the activity of new catalysts in the deprotecting process with that of a commercial one containing 10% Pd over carbon, supplied by Fluka (ref. 75990).

scholarly journals The principle of formaldehyde, alcohol, and acetone titrations. With a discussion of the proof and implication of the zwitterion conception

1934 ◽  
Vol 115 (792) ◽  
pp. 121-141 ◽  
Keyword(s):  
Amino Acids ◽  
Carboxyl Groups ◽  
Recent Discussion ◽  
Amino Groups ◽  
Chemical Methods ◽  
Titration Method ◽  
Physico Chemical ◽  
Empirical Argument ◽  
Chemical Evidence

Consideration of the implications of the zwitterion hypothesis of Bjerrum (1923) makes it desirable to state afresh the principles underlying the methods commonly employed in the titration of amino-acids. Deductions of considerable theoretical importance, cf., e. g ., Calvery (1933) are still being made on the supposition that the alkalimetric formaldehyde titration method of Sørensen (1907) and the corresponding alcohol method of Foreman (1920) and of Willstätter and Waldschmidt-Leitz (1921) estimate the carboxyl groups of amino-acids whilst the acidimetric acetone titration of Linderstrøm-Lang (1928) estimates the amino-groups. Yet the zwitterion hypothesis indicates that this assumption is the reverse of the truth. Discussion is greatly facilitated by collective consideration of recent physico-chemical evidence clarifying the principles upon which these common bio-chemical methods rest. In a recent discussion of two of the titrimetric methods (Van Slyke and Kirk, 1933) the existence of this evidence is ignored, so that it becomes necessary to systematize and elaborate the empirical argument of these authors in the light of the relevant investigations of Grünhut (1919), Cray and Westrip (1925), Michaelis and Mizutani (1925), Birch and Harris (1930, b ), and Levy (1933). At the same time new and useful developments are indicated.

scholarly journals Effect of different D-amino acids on biofilm formation of mixed microorganisms

2021 ◽  
Author(s):  
Xinying Su ◽  
Xin Cheng ◽  
Yu Wang ◽  
Jintao Luo
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Biofilm Formation ◽  
Membrane Surface ◽  
Promoting Effect ◽  
Inhibition Effect ◽  
Excitation Emission Matrix ◽  
Reversible Adhesion ◽  
Adhesion Efficiency ◽  
Tyrosine D

Abstract This study aimed to determine the effects of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine on biofilm formation of mixed microorganisms. Results showed that, in the attachment stage, D-amino acids caused significant reduction in adhesion efficiency of mixed microorganisms to membrane surface. Moreover, D-amino acids have a promoting effect on the reversible adhesion of mixed microorganisms. The addition of D-amino acid generally inhibited the biofilm biomass, of which D-tyrosine has the best inhibition effect. With the effect of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine, the protein in extracellular polymeric substance (EPS) decreased by 8.21%, 7.65%, 3.51% and 11.31%, respectively. The carbohydrates in EPS decreased by 29.53%, 21.44%, 14.60% and 10.54%, respectively. The results of excitation-emission matrix spectra (EEMs) suggested that the structural properties of the tyrosine-like proteins, tryptophan-like protein and humic-like acid might have changed by the D-amino acids.

Automated Determination of Free Amino Groups in Serum and Plasma Using 2,4,6-Trinitrobenzene Sulfonate

1969 ◽  
Vol 15 (9) ◽  
pp. 891-901 ◽  
Author(s):  
D W Palmer ◽  
T Peters
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Clinical Applications ◽  
Amino Groups ◽  
Automated Method ◽  
Total Free Amino Acids ◽  
Colored Complexes ◽  
Automated Determination

Abstract A simple automated method is described for determining the level of total free amino acids in the blood. The method utilizes the AutoAnalyzer, and is based on the formation of colored complexes by uniting free amino groups with 2,4,6-trinitrobenzene sulfonate (TNBS). Proteins do not interfere because the free amino acids are first separated by dialysis. Characteristics of the reaction and potential clinical applications of the procedure are discussed.

Frameworks of Transition Metals and Linkers with Two or More Functional Groups

2000 ◽  
Vol 658 ◽  
Author(s):  
Slavi C. Sevov
Keyword(s):  
Amino Acids ◽  
Transition Metals ◽  
Functional Groups ◽  
Organic Molecules ◽  
Layered Structures ◽  
Amino Groups ◽  
Effect Of Ph ◽  
Open Framework ◽  
Acidic Conditions ◽  
New Compounds

ABSTRACTHybrid inorganic/organic materials with open-framework or layered structures are known for many transition metals linked by functionalized organic molecules such as organic diphosphonates, polycarboxylates, polynitriles, etc., species with more than one equivalent functional groups. We have studied the effect of pH on such a system of cobaltmethylenediphosphonate and report three new compounds, Na3Co[(O3PCH2PO3)(OH)],Na2Co(O3PCH2PO3)•H2O, and Co2[(O3PCH2PO3)(H2O)], that form at very basic, moderately basic, and acidic conditions, respectively. More interestingstructural chemistry should be expected from linkers with two or more different functionalities. Both the carboxylic and phosphonic groups in carboxyethylphosphonic acid are used to coordinate to cobalt or calcium atoms in the new compounds Co3(O3PCH2CH2COO)2•6H2O and Ca(O3PCH2CH2COOH)•H2O. Taking one more step further in complexity we have also studied linkers with three different functional groups, phosphonated amino acids. The structures of two new compounds, Zn(O3PCH2CH(NH3)COO) and Zn(O3PCH2CH2CH(NH3)COO), are threedimensional frameworks made of zinccoordinated by both the carboxylic and phosphonic ends of the organic molecules. The amino groups are protonated and terminal in the voids of the frameworks.

Condensation de la poly-L-lysine et de la poly- L-ornithine avec des dérivés de bases puriques et de sulfamides

1969 ◽  
Vol 47 (19) ◽  
pp. 3641-3646 ◽  
Author(s):  
Louis Berlinguet ◽  
Jacky Gautier
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Free Amino ◽  
Sulfonyl Chloride ◽  
Amino Groups ◽  
Carbodiimide Method

Free ε-amino groups of poly-L-lysine and poly-L-ornithine were alkylated in aqueous solution with 6-chloropurine and 6-chloropurine-riboside, were acylated with 4-acetylamino benzene sulfonyl chloride, and were condensed with N-(4-acetylamino benzene sulfonyl)-glycine using carbodiimide method. Approximately 50% of the free amino groups of the basic polypetides were substituted. The same method was used to prepare poly-α-amino acids bearing radioactive substituants.

scholarly journals Supplementation of branched-chain amino acids to a reduced-protein diet improves growth performance in piglets: involvement of increased feed intake and direct muscle growth-promoting effect

2016 ◽  
Vol 115 (12) ◽  
pp. 2236-2245 ◽  
Author(s):  
Liufeng Zheng ◽  
Hongkui Wei ◽  
Chuanshang Cheng ◽  
Quanhang Xiang ◽  
Jiaman Pang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Growth Performance ◽  
Feed Intake ◽  
Muscle Growth ◽  
Branched Chain Amino Acids ◽  
Promoting Effect ◽  
Weanling Piglets ◽  
Growth Promoting ◽  
T1 And T2 ◽  
Branched Chain

AbstractThe aim of this study was to investigate whether supplementing branched-chain amino acids (AA) (BCAA) along with a reduced-protein diet increases piglet growth, and whether elevated feed intake and muscle growth-promoting effect contribute to this improvement. In Expt 1, twenty-eight weanling piglets were randomly fed one of the following four diets: a positive control (PC) diet, a reduced-protein negative control (NC) diet, an NC diet supplemented with BCAA to the same levels as in the PC diet (test 1 (T1)) and an NC diet supplemented with a 2-fold dose of BCAA in T1 diet (test 2 (T2)) for 28 d. In Expt 2, twenty-one weanling piglets were randomly assigned to NC, T1 and pair-fed T1 (P) groups. NC and T1 diets were the same as in Expt 1, whereas piglets in the P group were individually pair-fed with the NC group. In Expt 1, the NC group had reduced piglet growth and feed intake compared with the PC group, which were restored in T1 and T2 groups, but no differences were detected between T1 and T2 groups. In Expt 2, T1 and P groups showed increases in growth and mass of some muscles compared with the NC group. Increased feed intake after BCAA supplementation was associated with increased mRNA expressions of agouti-related peptide and co-express neuropeptide Y (NPY) and phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase 1 (S6K1), as well as decreased mRNA expressions of melanocortin-4 receptor and cocaine- and amphetamine-regulated transcript and phosphorylation of eukaryotic initiation factor 2α in the hypothalamus. No differences were observed among PC, T1 and T2 groups except for higher NPY mRNA expression in the T2 group than in the PC group (Expt 1). Phosphorylation of mTOR and S6K1 in muscle was enhanced after BCAA supplementation, which was independent of change in feed intake (Expt 2). In conclusion, supplementing BCAA to reduced-protein diets increases feed intake and muscle mass, and contributes to better growth performance in piglets.

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