THE ACTION OF SULPHURIC ACID ON GLIADIN: WITH SPECIAL REFERENCE TO THE N-PEPTIDYL→O-PEPTIDYL BOND REARRANGEMENT

1955 ◽  
Vol 33 (11) ◽  
pp. 1638-1648 ◽  
Author(s):  
L. K. Ramachandran ◽  
W. B. McConnell
Keyword(s):  
Sulphuric Acid ◽  
Direct Evidence ◽  
Acyl Migration ◽  
Hydroxyl Group ◽  
Amino Groups ◽  
Peptide Bonds ◽  
Alternative Scheme ◽  
Apparent Homogeneity ◽  
Secondary Reactions ◽  
Bond Rearrangement

Treatment of gliadin with sulphuric acid transposes peptide bonds of serine from the amino to the hydroxyl group. Maximum transposition, 60–70% of the theoretical, occurs when the protein is treated with anhydrous sulphuric acid at 0°C. for 35 hr. No rearrangement was detected at threonine residues. Examination of the peptide material, obtained from the rearranged protein by Elliott's degradation method, indicates apparent "homogeneity". In an alternative scheme for the degradation, nitrous acid deamination of free amino groups was used. The resulting loss in serine content of the protein is direct evidence for the acyl migration of peptide bonds. Incorporation of sulphur and partial disappearance of several amino acids accompany the sulphuric acid treatment. The occurrence of these secondary reactions imposes limitations on the use of sulphuric acid as a reagent for the specific fission of peptide bonds.

THE ACTION OF ANHYDROUS ACIDS ON ATP:CREATINE PHOSPHOTRANSFERASE

1962 ◽  
Vol 40 (5) ◽  
pp. 1018-1022 ◽  
Author(s):  
Florante A. Quiocho ◽  
Felix Friedberg
Keyword(s):  
Amino Acids ◽  
Phosphoric Acid ◽  
Formic Acid ◽  
Sulphuric Acid ◽  
Acyl Migration ◽  
Peptide Bonds ◽  
Hydrolysis Of ◽  
Anhydrous Formic Acid

Treatment of ATP:creatine phosphotransferase with anhydrous sulphuric acid permits transposition of 24% of the threonine residues and 69% of the serine residues. Treatment with anhydrous phosphoric acid yields similar results: 41% of the threonine residues and 60% of the serine residues are rearranged. Anhydrous formic acid does not induce an N- to O-acyl migration in the protein.Non-specific hydrolysis of peptide bonds or destruction of certain amino acids that might have occurred simultaneously with rearrangement during the anhydrous sulphuric or anhydrous phosphoric acid appears to be very slight. When the protein is treated with anhydrous sulphuric acid, however, phenylalanine "disappears" almost completely from the chromatogram.

scholarly journals Synthesis of Gold Nanoparticles Using p-Aminobenzoic Acid and p-Aminosalicylic Acid as Reducing Agent

2019 ◽  
Vol 19 (1) ◽  
pp. 68
Author(s):  
Abdul Aji ◽  
Eko Sri Kunarti ◽  
Sri Juari Santosa
Keyword(s):  
Gold Nanoparticles ◽  
Optimum Condition ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydroxyl Group ◽  
Synthesis Process ◽  
Aminobenzoic Acid ◽  
Aminosalicylic Acid ◽  
Amino Groups ◽  
Transmission Electron

Synthesis of gold nanoparticles (AuNPs) by reduction of HAuCl4 with p-aminobenzoic acid and p-aminosalicylic acid as a reducing agent was investigated. This work was conducted in order to determine the optimum condition of AuNPs synthesis and examine the effect of the hydroxyl group in p-aminosalicylic acid towards the size, shape, and stability of the synthesized gold nanoparticles (AuNPs). The optimum condition of the gold nanoparticles synthesis was determined by UV/Vis spectrophotometer, the shape and size of gold nanoparticles were measured by Transmission Electron Microscope (TEM). The synthesis process was started by reacting HAuCl4 and the reducing agents in an aqueous solution at 86 ºC. The initial gold concentration, reducing agents concentration and pH were varied in order to obtain the optimum condition. In the optimum condition, the results showed that p-aminosalicylic acid containing both hydroxyl and amino groups performed higher reduction ability compared to p-aminobenzoic acid that only containing an amino group. Reducing agents which have a hydroxyl group (p-aminosalicylic acid) could produce AuNPs with a smaller concentration of HAuCl4 than p-aminobenzoic acid. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable and had a smaller particle size compared to its counterpart that is synthesized with p-aminobenzoic acid.

Studies of the Wallach Transformation. II. Steric Effects in Some Symmetrically Disubstituted Azoxybenzenes

1951 ◽  
Vol 4 (2) ◽  
pp. 185
Author(s):  
PH Gore ◽  
GK Hughes
Keyword(s):  
Sulphuric Acid ◽  
Important Influence ◽  
Steric Effects ◽  
Hydroxyl Group ◽  
Azoxy Compounds ◽  
Point Of Entry ◽  
Substituent Group

Study of the behaviour of symmetrical azoxy compounds in the Wallach Transformation shows the important influence of size of a substituent group ortho to the point of entry of the hydroxyl group.�The various processes known to occur in a solution of azoxybenzene in sulphuric acid are discussed.

Oberflächenverbindungen von Übergangsmetallen, XX Komplexe von Oberflächen-Chrom(II) mit Olefinen /Surface Compounds of Transition Metals, XX Complexes of Surface Chromium(II) with Olefines

1978 ◽  
Vol 33 (11) ◽  
pp. 1278-1284 ◽  
Author(s):  
Hans-Ludwig Krauss ◽  
Ulrich Westphal
Keyword(s):  
Double Bond ◽  
Transition Metals ◽  
Oxidative Addition ◽  
Metal Bond ◽  
Surface Compounds ◽  
Secondary Reactions ◽  
Bond Rearrangement

Abstract Surface chromium(II) supported on silica forms 1:1 and 1:2 complexes with defines; polyenes prefer chelate structures. For the ligand-to-metal bond a “Zeise-Salt” type is postulated. Secondary reactions include cis-trans isomerisation, shift of double bond, rearrangement of C-framework and polymerization/oligomerization. Cyclopentadiene obviously gives a h5 -cyclopentadienyl/hydrogen complex by oxidative addition followed by H2 emission and formation of a h5 -cp-CrIII complex; in this case the metal can be split off from the support by H+ without cleavage of the cp-Cr-bond.

scholarly journals Interlamellar amino functionalization of kaolinite

1997 ◽  
Vol 75 (11) ◽  
pp. 1766-1772 ◽  
Author(s):  
James J. Tunney ◽  
Christian Detellier
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Nmr Spectroscopy ◽  
Structural Model ◽  
Hydroxyl Group ◽  
Two Dimensional ◽  
Amino Groups ◽  
Surface Hydroxyl ◽  
Silicate Surface ◽  
Ir Analysis

The interlamellar surface of kaolinite has been modified with molecules possessing amino functionalities. Either the dimethyl sulfoxide intercalate of kaolinite (Kao/DMSO) or the N-methylformamide intercalate of kaolinite (Kao/NMF) were used as starting materials. One of the products, an ethanolamine functionalized kaolinite (Kao–EOA) was resistant to thermal decomposition in both air and N2 atmospheres up to temperatures greater than 150 °C. Based on results from thermal analysis, IR analysis, 13CCP/MAS NMR spectroscopy, and elemental analysis, a structural model is proposed in which every third interlayer surface hydroxyl group on the aluminol (Al-OH) surface of kaolinite is either replaced with an interlayer Al-OCH2CH2NH2 group or is strongly H-bonded to an aminoalcohol molecule. A mixture of both types of linkages could coexist. The amino groups that point away from this surface are each keyed into the -(SiO−)6 macro-rings of the adjacent silicate surface, resulting in an amino-functionalized ordered two-dimensional organo-mineral assembly. Keywords: kaolinite, halloysite, organo-mineral nanocomposites, clay functionalization, supramolecular assemblies.

scholarly journals 1H NMR Elucidation of Observed Stable Sugar-NaCl-water Complexes in Aqueous Solution

2021 ◽  
Author(s):  
Gan Zhu ◽  
Hui Li ◽  
Yiqun Li ◽  
Liuqun Gu
Keyword(s):  
1H Nmr ◽  
Direct Evidence ◽  
Aqueous Media ◽  
Hydroxyl Group ◽  
Chemical Transformations ◽  
New Findings ◽  
Pka Value ◽  
Different Types ◽  
Atom Level ◽  
Hydrogen Bondings

The solvation of sugars in aqueous media matters in the understanding of biological systems and carbohydrate transformations. Generally, 2 – 4 water units were proposed to interact with each hydroxyl group in monosaccharides via different types of hydrogen bondings at room temperature in previous studies. Presence of NaCl was known to perturb hydrogen bondings of sugar hydrates. However, direct evidence to elucidate mechanism at atom level is very rare even though “NaCl Effect” was well known in biomass chemical transformations. Here we report 1H NMR elucidation evidences of mono/disaccharides hydrates in different concentration of NaCl aqueous solutions. We here conclude two new findings: 1) under ideal usage of NaCl, different mono/disaccharides hydrates are likely to be converted into a stable sugar-NaCl-water form; 2) pKa value of different hydroxyls in mono/disaccharides has intangible influence on hydrate form change induced by NaCl. An ideal NaCl usage based on maximum of 1H NMR shift was proposed.

scholarly journals High summertime aerosol organic functional group concentrations from marine and seabird sources at Ross Island, Antarctica, during AWARE

2018 ◽  
Vol 18 (12) ◽  
pp. 8571-8587 ◽  
Author(s):  
Jun Liu ◽  
Jeramy Dedrick ◽  
Lynn M. Russell ◽  
Gunnar I. Senum ◽  
Janek Uin ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Acid Group ◽  
Hydroxyl Group ◽  
Anthropogenic Emissions ◽  
Natural Factor ◽  
Natural Sources ◽  
Organic Components ◽  
West Antarctic ◽  
Secondary Reactions ◽  
The Fourier Transform

Abstract. Observations of the organic components of the natural aerosol are scarce in Antarctica, which limits our understanding of natural aerosols and their connection to seasonal and spatial patterns of cloud albedo in the region. From November 2015 to December 2016, the ARM West Antarctic Radiation Experiment (AWARE) measured submicron aerosol properties near McMurdo Station at the southern tip of Ross Island. Submicron organic mass (OM), particle number, and cloud condensation nuclei concentrations were higher in summer than other seasons. The measurements included a range of compositions and concentrations that likely reflected both local anthropogenic emissions and natural background sources. We isolated the natural organic components by separating a natural factor and a local combustion factor. The natural OM was 150 times higher in summer than in winter. The local anthropogenic emissions were not hygroscopic and had little contribution to the CCN concentrations. Natural sources that included marine sea spray and seabird emissions contributed 56 % OM in summer but only 3 % in winter. The natural OM had high hydroxyl group fraction (55 %), 6 % alkane, and 6 % amine group mass, consistent with marine organic composition. In addition, the Fourier transform infrared (FTIR) spectra showed the natural sources of organic aerosol were characterized by amide group absorption, which may be from seabird populations. Carboxylic acid group contributions were high in summer and associated with natural sources, likely forming by secondary reactions.

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