scholarly journals Chemical Methods for N‐ and O‐Sulfation of Small Molecules, Amino Acids and Peptides

ChemBioChem ◽  
2020 ◽  
Vol 21 (7) ◽  
pp. 938-942 ◽  
Author(s):  
Anna Mary Benedetti ◽  
Daniel M. Gill ◽  
Chi W. Tsang ◽  
Alan M. Jones
Keyword(s):  
Amino Acids ◽  
Small Molecules ◽  
Chemical Methods

Research Regarding Content in Amino-acids and Biological Value of Proteins from Polyodon spathula Sturgeon Meat

2017 ◽  
Vol 68 (5) ◽  
pp. 1063-1069
Author(s):  
Cristina Simeanu ◽  
Daniel Simeanu ◽  
Anca Popa ◽  
Alexandru Usturoi ◽  
Dan Bodescu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nutritive Value ◽  
Essential Amino Acids ◽  
Meat Production ◽  
Age Group ◽  
Chemical Methods ◽  
Biological Value ◽  
Polyodon Spathula ◽  
The One ◽  
Total Amino Acids

Polyodon spathula sturgeon breed is successfully reared in Romania in many fishery farms for meat production and it is capitalized on domestic market as consumption fish. In the current paper were studied a number of 1400 sturgeons from Polyodon spathula breed (1200 individuals of one summer - P.s.0+ and 200 individuals of fourth summers - P.s.3+). From this flock were weighted around 10%, for each age group, and for laboratory determinations were chosen 10 fishes for each age with the corporal mass close to the group mean. After analysing the fillets gathered from the studied fishes for establishing the chemical characteristics, nutritive and biological values of proteins were drawn some interesting conclusions. So, regarding chemical composition we notice that in the meat of analysed fishes water is in a rate of 75.41% at P.s.3+ and 78.37% for P.s.0+; proteins - between 18.08% for P.s.0+ and 19.89% for P.s.3+, values which place those fishes in the group of protein fishes; lipids - between 2.45% and 3.45%, values which situated those sturgeons in category of fishes with a low content in lipids; collagen � 3.83% at P.s.0+ and 4.14% at P.s.3+ which indicate low values for proteins of weak quality in the meat of those sturgeons. Study of nutritive value for the analysed fishes indicate the fact that fishes P.s.0+ have a mediocre nutritive value, having the ratio w/p of 4.33 while sturgeons P.s.3+ were placed in the 2nd category � fishes with a good nutritive value (rate w/p = 3.79). Energetic value of the studied fillets was 97.39 kcal/100 g for P.s.0+ and 114.31 kcal/100 g for P.s.3+, which enlightened an increase of nutritive value with aging, fact especially due to accumulation of adipose tissue. Study of proteins quality, through the presence of those 8 essential amino-acids in the meat of analysed fishes, show the fact that at sturgeons P.s.0+ proportion of essential amino-acids was 20.88% from total amino-acids, while at sturgeons P.s.3+ was 26.23%, fact which enlightened an increasing of proteins� biological value with fish aging. This fact was also shown by calculation of proteins� biological value through chemical methods (EAA index); calculated value for sturgeons P.s.0+ was a little bit lower (118.73) than the one calculated for sturgeons P.s.3+ (118.79).

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 Site-Selective C-C Modification of Proteins at Neutral pH Using Organocatalyst-Mediated Cross Aldol Ligations

2018 ◽  
Author(s):  
Martin A. Fascione ◽  
Richard J. Spears ◽  
Robin L. Brabham ◽  
Darshita Budhadev ◽  
Tessa Keenan ◽  
...  
Keyword(s):  
Small Molecules ◽  
Stable Carbon ◽  
Biological Mechanisms ◽  
Large Excess ◽  
Reaction Conditions ◽  
Chemical Methods ◽  
Neutral Ph ◽  
Chemical Modification Of Proteins ◽  
A Site ◽  
Site Selective

The bioconjugation of proteins with small molecules has proved an invaluable strategy for probing and perturbing dynamic biological mechanisms. The general use of chemical methods for the functionalisation of proteins remains limited however by the frequent requirement for complicated reaction partners to be present in large excess, and harsh reaction conditions which are incompatible with many protein scaffolds. Herein we describe a site-selective organocatalyst-mediated protein aldol ligation (OPAL) that affords stable carbon-carbon linked bioconjugates at neutral pH under biocompatible conditions. OPAL enables rapid chemical modification of proteins within an hour using simple aldehyde probes in minimal excess, and is utilised here in the selective affinity tagging of proteins in cell lysate. Furthermore we demonstrate that the b-hydroxy aldehyde product of the OPAL can be functionalised a second time at neutral pH in a subsequent organocatalyst-mediated oxime ligation. This tandem strategy is showcased in the ‘chemical mimicry’ of a previously inaccessible natural dual post-translationally modified protein integral to the pathogenesis of the neglected tropical disease Leishmaniasis. <br>

Selective Chemical Deuteration of Aromatic Amino Acids: A Retrospective

1997 ◽  
Author(s):  
K.S. Matthews ◽  
R. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Protein Hydrolysate ◽  
Aromatic Amino Acids ◽  
Cellular Protein ◽  
Target Protein ◽  
Chemical Methods ◽  
Lactose Repressor ◽  
Selective Deuteration

In 1970 when we began post-doctoral work in the laboratory of Professor Oleg Jardetzky, selective deuteration of proteins to limit the number of protons present in the system for subsequent analysis was a newly developed and effective technique for NMR exploration of protein structure (Crespi et al., 1968; Markley et al., 1968). This approach allowed more facile assignment of specific resonances and generated the potential to follow the spectroscopic behavior of protons for a specific amino acid sidechain over a broad range of conditions. The primary method for labeling at that time involved growth of microorganisms (generally bacteria or algae) in D2O, followed by isolation of the deuteratedamino acids from a cellular protein hydrolysate. The amino acids isolated were, therefore, completely deuterated. Selective deuteration of a target protein was achieved by growing the producing organism on a mixture of completely deuterated and selected protonated amino acids under conditions that minimized metabolic interconversion of the amino acids. In one-dimensional spectra, aromatic amino acid resonances occur well downfield of the aliphatic resonances, and this region can therefore be examined somewhat independently by utilizing a single protonated aromatic amino acid to simplify the spectrum of the protein. However, the multiple spectral lines generated by aromatic amino acids can be complex and overlapping, precluding unequivocal interpretation. To address this complication, chemical methods were developed to both completely and selectively deuterate side chains of the aromatic amino acids, thereby avoiding the costly necessity of growing large volumes of microorganisms in D2O and subsequent tedious isolation procedures. In addition, selective deuteration of the amino acids simplified the resonance patterns and thereby facilitated assignment and interpretation of spectra. The methods employed were based on exchange phenomena reported in the literature and generated large quantities of material for use in growth of microorganisms for subsequent isolation of selectively labeled protein (Matthews et al., 1977a). The target protein for incorporation of the selectively deuterated aromatic amino acids generated by these chemical methods was the lactose repressor protein from Escherichia coli, and greatly simplified spectra of this 150,000 D protein were produced by this approach.

scholarly journals P450BM3-Catalyzed Oxidations Employing Dual Functional Small Molecules

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 567 ◽  
Author(s):  
Willot ◽  
Tieves ◽  
Girhard ◽  
Urlacher ◽  
Hollmann ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hydrogen Peroxide ◽  
Cytochrome P450 ◽  
Small Molecules ◽  
Bacillus Megaterium ◽  
Cytochrome P450 Monooxygenase ◽  
Oxidation Reactions ◽  
P450 Monooxygenase ◽  
Dual Functional ◽  
Catalytic Epoxidation

A set of dual functional small molecules (DFSMs) containing different amino acids has been synthesized and employed together with three different variants of the cytochrome P450 monooxygenase P450BM3 from Bacillus megaterium in H2O2-dependent oxidation reactions. These DFSMs enhance P450BM3 activity with hydrogen peroxide as an oxidant, converting these enzymes into formal peroxygenases. This system has been employed for the catalytic epoxidation of styrene and in the sulfoxidation of thioanisole. Various P450BM3 variants have been evaluated in terms of activity and selectivity of the peroxygenase reactions.

Small Molecules that Mimic Components of Bioactive Protein Surfaces

2004 ◽  
Vol 57 (9) ◽  
pp. 855 ◽  
Author(s):  
David P. Fairlie
Keyword(s):  
Amino Acids ◽  
Antiviral Activity ◽  
Small Molecules ◽  
G Protein ◽  
Selective Inhibition ◽  
Structural Components ◽  
Protein Surfaces ◽  
Biological Responses ◽  
Anti Inflammatory ◽  
G Protein Coupled

Small molecules designed to mimic specific structural components of a protein (peptide strands, sheets, turns, helices, or amino acids) can be expected to display agonist or antagonist biological responses by virtue of interacting with the same receptors that recognize the protein. Here we describe some minimalist approaches to structural mimetics of amino acids and of strand, turn, or helix segments of proteins. The designed molecules show potent and selective inhibition of protease, transferase, and phospholipase enzymes, or antagonism of G-protein coupled or transcriptional receptors, and have potent anti-tumour, anti-inflammatory, or antiviral activity.

scholarly journals Corticotropin-releasing factor receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Frank M. Dautzenberg ◽  
Dimitri E. Grigoriadis ◽  
Richard L. Hauger ◽  
Victoria B. Risbrough ◽  
Thomas Steckler ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Small Molecules ◽  
Corticotropin Releasing Factor ◽  
Releasing Hormone ◽  
Endogenous Peptides ◽  
Amino Acid Peptide ◽  
Kd Values ◽  
Urocortin 1 ◽  
Urocortin 3

Corticotropin-releasing factor (CRF, nomenclature as agreed by the NC-IUPHAR subcommittee on Corticotropin-releasing Factor Receptors [30]) receptors are activated by the endogenous peptides corticotrophin-releasing hormone, a 41 amino-acid peptide, urocortin 1, 40 amino-acids, urocortin 2, 38 amino-acids and urocortin 3, 38 amino-acids. CRF1 and CRF2 receptors are activated non-selectively by CRH and UCN. CRF2 receptors are selectively activated by UCN2 and UCN3. Binding to CRF receptors can be conducted using radioligands [125I]Tyr0-CRF or [125I]Tyr0-sauvagine with Kd values of 0.1-0.4 nM. CRF1 and CRF2 receptors are non-selectively antagonized by α-helical CRF, D-Phe-CRF-(12-41) and astressin. CRF1 receptors are selectively antagonized by small molecules NBI27914, R121919, antalarmin, CP 154,526, CP 376,395. CRF2 receptors are selectively antagonized by antisauvagine and astressin 2B.

scholarly journals Evaluation of Two Major Rhodiola Species and the Systemic Changing Characteristics of Metabolites of Rhodiola crenulata in Different Altitudes by Chemical Methods Combined with UPLC-QqQ-MS-Based Metabolomics

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4062
Author(s):  
Xueda Dong ◽  
Yiwen Guo ◽  
Chuan Xiong ◽  
Liwei Sun
Keyword(s):  
Amino Acids ◽  
Antioxidant Activities ◽  
Phenylpropanoid Pathway ◽  
Rhodiola Rosea ◽  
Chemical Methods ◽  
Phenolic Components ◽  
History Of ◽  
Rhodiola Crenulata ◽  
History Of Use ◽  
Different Altitudes

Rhodiola species have a long history of use in traditional medicine in Asian and European countries and have been considered to possess resistance to the challenges presented by extreme altitudes. However, the influence of different Rhodiola species on quality is unclear, as well as the influence of altitude on phytochemicals. In this study, the phenolic components and antioxidant abilities of two major Rhodiola species are compared, namely Rhodiolacrenulata and Rhodiola rosea, and the metabolomes of Rhodiolacrenulata from two representative elevations of 2907 and 5116 m are analyzed using a UPLC-QqQ-MS-based metabolomics approach. The results show that the phenolic components and antioxidant activities of Rhodiolacrenulata are higher than those of Rhodiola rosea, and that these effects in the two species are positively correlated with elevation. Here, 408 metabolites are identified, of which 178 differential metabolites (128 upregulated versus 50 downregulated) and 19 biomarkers are determined in Rhodiola crenulata. Further analysis of these differential metabolites showed a significant upregulation of flavonoids, featuring glucosides, the enhancement of the phenylpropanoid pathway, and the downregulation of hydrolyzed tannins in Rhodiola crenulata as elevation increased. Besides, the amino acids of differential metabolites were all upregulated as the altitude increased. Our results contribute to further exploring the Rhodiola species and providing new insights into the Rhodiola crenulata phytochemical response to elevation.

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