Synthesis and evaluation of chiral β-amino acid-based low-molecular-weight organogelators possessing a methyl/trifluoromethyl side chain

2019 ◽  
Vol 43 (7) ◽  
pp. 2882-2887 ◽  
Author(s):  
Koichi Kodama ◽  
Ryuta Kawamata ◽  
Takuji Hirose
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Supramolecular Structures ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Side Chains ◽  
Low Molecular Weight Organogelators

Impacts of side-chains and chirality of organogelators derived from β-amino acids are described with their supramolecular structures.

Constructing a Syntheses Table of the Standard Amino Acid Based on the PAM250 Matrix

2011 ◽  
Vol 335-336 ◽  
pp. 1279-1284
Author(s):  
Xiao Hong Shi ◽  
Xiang Hong Wang
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Physicochemical Properties ◽  
Side Chain ◽  
Side Chains ◽  
Chemical Structures ◽  
Naturally Occurring ◽  
Standard Amino Acid ◽  
Similar Amino Acid

It is well known that there are some similarities among various naturally occurring amino acids. The standard amino acids have been grouped by their general properties and the chemical structures of their side chains. In this paper we divided the molecular weight of amino acid into two parts: backbone molecular weight Mband side chain molecular weight Ms. We naturally grouped the amino acids into two sets according to the rate of Ms/ Mb. We developed a method to construct a syntheses table to reflect the relevant physicochemical properties based on the PAM250 matrix and successfully established an elegant table of the twenty amino acids. Our work proved that PAM250 matrix could be used not only in finding reasonable alignments but also in grouping similar amino acid.

Unusual Molecular and Supramolecular Structures of Chiral Low Molecular Weight Organogelators with Long Perfluoroalkyl Chains

2018 ◽  
Vol 18 (7) ◽  
pp. 4200-4205 ◽  
Author(s):  
Toshiyuki Sasaki ◽  
Akiko Egami ◽  
Tomoko Yajima ◽  
Hidehiro Uekusa ◽  
Hisako Sato
Keyword(s):  
Molecular Weight ◽  
Supramolecular Structures ◽  
Low Molecular Weight ◽  
Low Molecular Weight Organogelators

Trans-tegumental absorption of L-alanine and L-leucine by a monogenean, Diclidophora merlangi

Parasitology ◽  
1978 ◽  
Vol 76 (1) ◽  
pp. 29-37 ◽  
Author(s):  
D. W. Halton
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Sea Water ◽  
Low Molecular Weight ◽  
Acid Uptake ◽  
Neutral Amino Acids ◽  
Freeze Dried ◽  
Significant Difference

SummaryAn in vitro investigation has been made of the relative roles of the gut and tegument in the absorption of the neutral amino acids L-alanine and L-leucine by a marine fish-gill parasite, Diclidophora merlangi. The use of ligatures to preclude oral ingestion of trace-labelled medium has proved inadequate, invariably damaging the tegument, as revealed by stereoscan electron microscopy, and resulting in artifactual levels of absorption. Three alternative procedures have given consistently reliable data on the route of entry of low molecular weight substrates. (1) Ultrastructural examination of worms previously incubated in electron-dense cationic tracers has shown that, in vitro, there is no oral intake of sea water. (2) The suspending of worms in trace-labelled medium with the mouth out of the medium and comparing amino acid uptake with that of worms totally immersed in medium has revealed no statistically significant difference in the absorption levels. (3) Application of section (freeze-dried) auto-radiography to detect diffusible isotope has demonstrated directly transtegumental absorption of a neutral amino acid. It is concluded from these experiments that Diclidophora has a tegumental transport system for absorbing certain neutral amino acids, and whilst, clearly, the worm is sanguinivorous and digests blood in a well-developed gut, it may also be capable of supplementing this diet with low molecular weight organic nutrient absorbed directly from sea water via the tegument.

Phenylalanine and derivatives as versatile low-molecular-weight gelators: design, structure and tailored function

2018 ◽  
Vol 6 (1) ◽  
pp. 38-59 ◽  
Author(s):  
Tanmay Das ◽  
Marleen Häring ◽  
Debasish Haldar ◽  
David Díaz Díaz
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Essential Amino Acid ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Design Structure ◽  
Hydrophobic Nature ◽  
Low Molecular Weight Gelators

Phenylalanine (Phe) is an essential amino acid classified as neutral and nonpolar due to the hydrophobic nature of the benzyl side chain.

Protein

1995 ◽  
Author(s):  
Roland Lüthy ◽  
David Eisenberg
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Isoelectric Point ◽  
Extinction Coefficient ◽  
Titration Curve ◽  
Side Chains ◽  
Pka Values ◽  
Extinction Coefficients ◽  
Molecular Weights

Given a protein sequence, the amino acid composition can be determined by counting the number of residues of each type. Then a molecular weight can be calculated by summing the molecular weights of the individual amino acid residues, taking into account the loss of one H2O molecule per peptide bond. Table 1 lists the molecular weights of the twenty amino acids and water. This approach assumes that the protein has not been covalently modified. Because of extensive glycosylation of some proteins, this approach can significantly underestimate the actual molecular weight. With the pKa values of Table 1, it is possible to calculate the theoretical charge of a protein at a given pH by summing the charges of the amino acid side chains and of the amino terminus and carboxyl terminus. By performing this calculation over a pH range, one obtains a theoretical titration curve and an isoelectric point (the pH at which the protein hasanetchargeof zero). This method assumes that all normally titratable groups are accessible to water, and that all side chains have the intrinsic pKa values listed in Table 1. This assumption is not completely correct, and consequently, the theoretical isoelectric point may differ from the experimentally determined value. Figure 1 shows the calculated titration curve for pancreatic ribonuclease: the calculated isoelectric point is 8.2, whereas the measured value is 9.6 (Lehninger, 1977). The calculation of extinction coefficients (Gill and von Hippel, 1989) is performed in much the same way as that of the isoelectric point Individual residues are treated as if they are free amino acids, and the overall extinction coefficient is calculated as the sum of the extinction coefficients of the residues. The same basic assumption is made: Residues are assumed to be in typical environments and not to show unusual absorption due to their local environments. In the case of the extinction coefficient, however, this assumption seems to be generally acceptable; calculated extinction coefficients are typically within a few percent of the experimentally determined value, and errors of more than 15% are rare (Gill and von Hippel, 1989).

Discussion: Amino-acid activation by individual enzymes

1958 ◽  
Vol 149 (936) ◽  
pp. 401-402
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Distribution Pattern ◽  
Mammary Tissue ◽  
Low Molecular Weight ◽  
Major Protein ◽  
Acid Activation ◽  
Amino Acid Activation ◽  
Interesting Paper

I should like to comment on one aspect of Dr Gutfreund’s interesting paper. As he mentioned, we have found evidence that amino acids, after becoming enzymically activated by ATP through the formation of an enzyme-bound amino acyladenylate compound, are transferred to a low molecular weight RNA which, by accident or design, resides in the same crude activating enzyme fraction. It is gratifying that Dr Gutfreund has found a distribution pattern of amino acids on this RNA which roughly agrees with the pattern in the major protein products of mammary tissue. He points out, however, that there is no such correlation when one looks at the pattern of amino-acid activation. Indeed, because of this anomaly, some workers have devised theories of activation involving transacylation steps to account for activation of those amino acids for which an enzyme has not been found. Dr Gutfreund implies that there is much confusion and mystery here, and even suggests that the specificity of activation might be accounted for by soluble RNA , rather than by individual enzymes.

scholarly journals The structure of a glycopeptide isolated from the yeast cell wall

1968 ◽  
Vol 109 (3) ◽  
pp. 419-432 ◽  
Author(s):  
R. Sentandreu ◽  
D. H. Northcote
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Cell Wall ◽  
Amino Acid ◽  
Yeast Cell ◽  
Aspartic Acid ◽  
Yeast Cell Wall ◽  
Low Molecular Weight ◽  
Elimination Reaction ◽  
Sephadex Column

1. Glycopeptides containing mannose were extracted from isolated yeast cell walls by ethylenediamine and purified by treatment with Pronase and fractionation on a Sephadex column. 2. A glycopeptide that appeared homogeneous on electrophoresis and ultracentrifugation had a molecular weight of 76000, and contained a high-molecular-weight mannan and approx. 4% of amino acids. 3. The amino acid composition of the peptide was determined. It was rich in serine and threonine and also contained glucosamine. No cystine and methionine were detected. 4. The glycopeptide underwent a β-elimination reaction when treated with dilute alkali at low temperatures. The reaction resulted in the release of mannose, mannose disaccharides and possibly other low-molecular-weight mannose oligosaccharides. During the β-elimination reaction the dehydro derivatives of serine and threonine were formed. One of the linkages between carbohydrate and amino acids in the glycopeptide is an O-mannosyl bond from mannose and mannose oligosaccharides to serine and threonine. 5. After the β-elimination reaction the bulk of the mannose in the form of the large mannan component was still covalently linked to the peptide. This polysaccharide was therefore attached to the amino acids by a linkage different from the O-mannosyl bonds to serine and threonine that attach the low-molecular-weight sugars. 6. Mannan was prepared from the glycopeptide and from the yeast cell wall by treatment of the fractions with hot solutions of alkali. The mannan contained aspartic acid and glucosamine and some other amino acids. The aspartic acid and glucosamine were present in equimolar amounts; the aspartic acid was the only amino acid present in an amount equivalent to that of glucosamine. Thus there is the possibility of a linkage between the mannan and the peptide via glucosamine and aspartic acid. 7. Mannose 6-phosphate was shown to be part of the mannan structure. Information about the structure of the mannan and the linkage of the glucosamine was obtained by periodate oxidation studies. 8. The glucosamine present in the glycopeptide could not be released by treatment with an enzyme preparation obtained from the gut of Helix pomatia. This enzyme released glucosamine from the intact cell wall. Thus there are probably at least two polymers containing glucosamine in the cell wall. 9. The biosynthesis of the mannan polymer in the yeast cell wall is discussed with regard to the two types of carbohydrate–amino acid linkages found in the glycoprotein.

scholarly journals Studien über Wespengift, I Niedermolekulare Bestandteile des Giftblasenextraktes von Paravespula vulgaris / Studies on Wasp Venom, I Low Molecular Weight Constituents of Venom Sac Extracts from Paravespula vulgaris

1981 ◽  
Vol 36 (6) ◽  
pp. 757-762 ◽  
Author(s):  
Hartmut Klein ◽  
Wittko Francke ◽  
Wilfried A. König
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Fatty Acids ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Acetic Acid ◽  
Quantitative Analysis ◽  
Amino Acid ◽  
Low Molecular Weight ◽  
Wasp Venom

Abstract Low molecular weight constituents of 3400 venom sacs of Paravespula vulgaris were extracted with water, diluted acetic acid, and methanol. After conversion to volatile derivatives carbohydrates, amino acids, fatty acids, other constituents of phospho lipids, and biogenic amines were identified by gas chromatography and mass spectrometry. Quantitative analysis was achieved for amino acids by amino acid analysis and for glucose by an enzymatic assay. Results are discussed with regard to biosynthesis of wasp toxins and phylogenetic aspects of hymenopteran venoms.

scholarly journals The Effect of a Peptide Substrate Containing an Unnatural Branched Amino Acid on Chymotrypsin Activity

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 242
Author(s):  
Yuuki Yamawaki ◽  
Tomoki Yufu ◽  
Tamaki Kato
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Unnatural Amino Acids ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Reaction Velocity ◽  
Natural Amino Acids

7-Amino-4-methylcoumarin (AMC) is a low molecular weight fluorescent probe that can be attached to a peptide to enable the detection of specific proteases, such as chymotrypsin, expressed in certain diseases. Because this detection depends on the specificity of the protease toward the peptidyl AMC, the development of specific substrates is required. To investigate the specificity of chymotrypsin, peptidyl AMC compounds incorporating four different amino acid residues were prepared by liquid-phase synthesis. Two unnatural amino acids, 2-amino-4-ethylhexanoic acid (AEH) and cyclohexylalanine (Cha), were used to investigate the substrate specificity as these amino acids have structures different from natural amino acids. AEH was synthesized using diethyl acetamidemalonate as a starting material. The substrate containing Cha had high hydrophobicity and showed a high reaction velocity with chymotrypsin. Although the AEH substrate with a branched side chain had high hydrophobicity, it showed a low reaction velocity. The substrate containing the aromatic amino acid phenylalanine was less hydrophobic than the Cha and AEH substrates, but chymotrypsin showed the highest specificity for this compound. These results demonstrated that the substrate specificity of chymotrypsin is not only affected by the hydrophobicity and aromaticity, but also by the structural expanse of amino acid residues in the substrate.

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