Stepwise Degradation Research Articles

A study of the oxidative degradation of phenol-formaldehyde polycondensates using infrared spectroscopy

An infrared spectrophotometric examination of the oxidative degradation of acid- and base-catalyzed phenol-formaldehyde polycondensates, novolaks and resoles, respectively, has been carried out in the temperature range form 100–200°C. The existence of structural moieties such as quinone methides and dibenzyl ethers in the cured phenolic resins systems could not be substantiated. The oxidation of phenolic resins was shown to be a stepwise degradation. Attack of oxygen, a surface reaction, was shown to be at the doubly activated methylene bridge linkage to form a substituted dihydroxybenzophenone system. This species was substantiated by the synthesis of polymers containing the ketonic linkage and their spectral identity to the degrading resin. The initial oxidation was shown to continue through the formation of quinone structures and secondary oxidation was shown to continue through the formation of quinone structures and secondary oxidation at these functional linkages to produce carboxylic acids as one of the fragments during chain scission. This degradation mechanism is in good agreement with other supporting experimental data concerning phenolic resin degradation.

212. Nucleotides. Part XLVII. The catalytic oxidation of nucleosides and nucleotides: a projected stepwise degradation of polynucleotides

212. Nucleotides. Part XLVII. The catalytic oxidation of nucleosides and nucleotides: a projected stepwise degradation of polynucleotides

End-turnover of rat-liver soluble RNA in vivo

By digestion with RNAase and stepwise degradation with snake-venom diesterase an end-turnover in soluble RNA of rat liver in vivo was demonstrated. Only the last nucleotide takes part in this end-turnover. The methods applied may be useful in studying sequence analysis in small-molecular-weight RNA.

Pathways of glucose dissimilation in the Laredo strain of Entamoeba histolytica

The Laredo strain of E. histolytica ferments glucose to produce carbon dioxide, hydrogen, acetic acid and ethanol as major products. All of the enzymes of the Embden-Meyerhof pathway were demonstrated and evidence for the functioning of this pathway was obtained by measuring the degree of labelling of the carbon dioxide produced from variously labelled glucose-C 14, and by stepwise degradation of the acetic acid derived from glucose-1-C 14. The relationship between the carbohydrate metabolism of E. histolytica and that of its bacterial associate in MS-F culture, Bacteroides symbiosus, is discussed. Enzymes capable of splitting 6-phosphogluconic acid were found in the ameba but not in the bacteria, while enzymes capable of utilizing ribose-5-phosphate were found in the bacteria but not in the ameba.

Inhibition of Autoprothrombin C Activity with Plasma

THE traditional enzyme considered in the literature on blood coagulation is thrombin. It has its origin in prothrombin, which is a plasma protein isolated from bovine plasma and characterized in terms of physical chemical properties1. When prothrombin activates, a stepwise degradation of the molecule occurs, and at least two of the intermediates, called autoprothrombin I and autoprothrombin II, can be involved in prothrombin activation2. When the prothrombin is fully activated the activation mixture contains another accelerator which is different from autoprothrombin I or autoprothrombin II. This accelerator was only recently discovered and called autoprothrombin C because there was prothrombin consumption when it was added to haemophilic plasma3. Autoprothrombin C has been separated from thrombin and is an enzyme4. A single molecule, prothrombin, is thus the source of two enzymes.

Distribution of radio activity in trismethylene‐trinitrobenzene obtained from 14C‐labelled 1,3,5‐trinitrobenzene: Nucleophilic aromatic addition V

AbstractThe previously suggested mechanism for the formation and the stepwise degradation of “trismethylene‐trinitrobenzene” (I) is confirmed by application of a 14C tracer technique. It is shown that all transformations occur without hydrogen shift.In this paper besides compound II a stereoisomer was considered, with a different position of the two cyclopropyl‐groups towards one another. Further investigation in collaboration with Mr. H. P. Venker has shown that formula II is most likely. However this may be, it is of no consequence for the conclusions reached in the present paper.

Heparin-released lipolytic and esterolytic activities of human and rabbit plasmas.

The enzymes released into both human and rabbit plasmas by heparin injection hydrolyzed, in addition to triglyceride moieties of lipoproteins, a number of mono- and diglycerides of C16 and C18 fatty acids after in vitro addition of the unemulsified glycerides to the plasma. In human postheparin plasma, these enzymes also hydrolyzed glycerides of butyric and caproic acids. The pure triglycerides and methyl or ethyl esters of C16 and C18 fatty acids were not substrates. The heparin-released activities for the hydrolysis of glycerides added in vitro persisted after all activity for the lipolysis of lipoproteins had been destroyed by heat. These activities also differed from lipoprotein lipase activity with respect to the effects of 1 m NaCl, dialysis, and aging the plasma at 4 C. It appears that heparin releases into the blood more than one enzyme or more than one form of an enzyme which may be involved in a stepwise degradation to fatty acids and glycerol of the triglyceride moieties of lipoproteins of density less than 1.007 g/ml.

THE BIOSYNTHESIS OF ERYTHRITOL AND GLYCEROL BY TORULOPSIS MAGNOLIAE. STUDIES WITH C14-LABELLED GLUCOSE

D-Glucose-1-C14, D-glucose-2-C14, D-glucose-3, 4-C14, and D-glucose-6-C14were dissimilated aerobically by washed cells of Torulopsis magnoliae. The major products formed were erythritol and glycerol.A method for the stepwise degradation of erythritol, after oxidation with Acetobacter suboxydans to L-erythrulose, is described. The distribution of radioactive carbon in the erythritol suggests that it is formed by a complex series of reactions in which enzymes of the transaldolase and transketolase type play a major part to give a four-carbon fragment which is then reduced to the tetritol. Enzymes of the Embden–Meyerhof pathway are probably concerned to a lesser extent.

The stepwise degradation of “trismethylene‐trinitrobenzene”: Nucleophilic aromatic addition II

Abstract“Trismethylenetrinitrobenzene” (I) has been degraded in five steps to cis‐ and trans‐nitrocyclopropanecarboxylic acid (IX and X), via the sequence, depicted in chart 1: I (C9H9N3O6 → II (C8H8N2O8) → V (C7H8N2O6) → VI (C7H8N2O7) → VII (C5H5NO6) → IX and X (C4H6NO4).II is a dicyclopropanedicarboxylic acid which very easily loses one molecule of CO2, to give no longer a carboxylic acid, but a lactone V.The unusual “decarboxylation‐lactonisation” process involves rupture of a CC bond in one three‐membered ring, and lactonisation with the carboxyl group attached to the unbroken three‐membered ring.The lactone V can be oxidised further to the keto acid VI and the nitro‐cyclopropanedicarboxylic acid VII. The latter upon decarboxylation affords IX and X. The structures of these hitherto all unknown degradation products are established by chemical, physical and spectroscopical (including NMR) evidence, thus lending support to the presence of two cyclopropane rings in “trismethylenetrinitrobenzene”.

THE BIOSYNTHESIS OF ERYTHRITOL AND GLYCEROL BY TORULOPSIS MAGNOLIAE. STUDIES WITH C14-LABELLED GLUCOSE

D-Glucose-1-C14, D-glucose-2-C14, D-glucose-3, 4-C14, and D-glucose-6-C14were dissimilated aerobically by washed cells of Torulopsis magnoliae. The major products formed were erythritol and glycerol.A method for the stepwise degradation of erythritol, after oxidation with Acetobacter suboxydans to L-erythrulose, is described. The distribution of radioactive carbon in the erythritol suggests that it is formed by a complex series of reactions in which enzymes of the transaldolase and transketolase type play a major part to give a four-carbon fragment which is then reduced to the tetritol. Enzymes of the Embden–Meyerhof pathway are probably concerned to a lesser extent.

A terminal peptide sequence of human haemoglobin?

IT was reported recently1,2,3 that the chemical difference between the normal human haemoglobin A and the abnormal haemoglobins S and C resides in a tryptic peptide, called peptide 4, to which the following structure was assigned: histidyl-valyl-leucyl-leucyl-threonyl-prolyl-glutamyl-glutamyl-lysine. In haemoglobins S and C the glutamic acid residue which is in italics is replaced by a valine and a lysine residue, respectively. Although the evidence available at the time of publication made the above structure appear likely, repeated attempts to confirm it by the Edman stepwise degradation method4 have not agreed with this formulation. We now wish to report that the sequence of peptide 4 in the haemoglobins A and C is as indicated in Table 1, with histidine in position 2 and valine as the N-terminal amino-acid. Furthermore, this peptide is likely to be N-terminal in one of the haemoglobin chains. The structure of peptide 4 from haemoglobin S is still under investigation, but it seems likely—especially in the light of the work of Hill and Schwartz (following communication) that its structure is as shown. It should be noted that the sequence around the amino-acid which changes and the changes themselves in these mutational alterations are not affected by the new structure.

N and C terminal groups of highly purified Bence-Jones protein

A highly purified preparation of Bence Jones protein has been submitted to analysis in order to identify the N and the C terminal residues. By application of the FDNB technique, it has been found that the aspartic acid is the N terminal amino acid. The C terminal sequence was studied with the use of carboxypeptidase for the stepwise degradation of peptide bonds; in this case, the terminal sequence was found to be Leu-Ala-Glu-Val.

LEAD TETRAACETATE OXIDATION OF OLIGOSACCHARIDES

Lead tetraacetate oxidation is shown to be useful for examining some structural features of trisaccharides and higher oligosaccharides. Generally, the oxidations follow a course similar to that found with the corresponding disaccharide. In some oligosaccharides, however, glycol groups which resist oxidation are encountered. Such groups are 2,3-trans glycols of central residues which are linked to adjacent residues by 1,4-glycosidic bonds. The apparent inability to complex with lead tetraacetate suggests a conformation for these sugar residues in acetic acid solution which differs from that of the corresponding monosaccharide glycopyranoside. Lead tetraacetate oxidation of oligosaccharides in which central residues are unaffected by the reagent constitutes a unique stepwise degradation of these compounds, and possible applications of the reaction are suggested.

Nucleotides. Part XXXI. The stepwise degradation of polyribonucleotides: model experiments

Nucleotides. Part XXXI. The stepwise degradation of polyribonucleotides: model experiments

Dégradation systématique des dinitrophénylpeptides (DNP-peptides)

A stepwise degradation of DNP-peptides has been developed. This procedure consists of reduction of the NO 2 groups of the DNP-peptide to NH 2 groups by catalytic hydrogenation in the presence of platinum. Treating at 50°C at pH 2 to 3, in an atmosphere of hydrogen, results in a lactam formation between the ortho-NH 2 group and the peptidic carbonyl group of the N-terminal amino acid; this forms a 7-amino-2-hydroxydihydroquinoxaline with liberation of an NH 2 group of the adjacent residue. After separation of the quinoxaline the residual peptide is treated by FDNB and the cycle of operations recommenced. Promising results have been obtained using this method for the degradation of some DNP-peptides.

A General Micromethod for the Stepwise Degradation of Peptides

A General Micromethod for the Stepwise Degradation of Peptides

A TECHNIQUE FOR STEPWISE DEGRADATION OF PROTEINS FROM THE AMINO-END1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA TECHNIQUE FOR STEPWISE DEGRADATION OF PROTEINS FROM THE AMINO-END1H. Fraenkel-ConratCite this: J. Am. Chem. Soc. 1954, 76, 13, 3606–3607Publication Date (Print):July 1, 1954Publication History Published online1 May 2002Published inissue 1 July 1954https://doi.org/10.1021/ja01642a085RIGHTS & PERMISSIONSArticle Views51Altmetric-Citations90LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (288 KB) Get e-Alerts Get e-Alerts

Identification of C-terminal residues in peptides and proteins through formation of thiohydantoins

The thiohydantoin method has been applied to the stepwise degradation of peptide chains from the carboxyl end. In the present procedure, the thiohydantoin intermediate formed from the peptide, ammonium thiocyanate, and acetic anhydride, was deacylated with barium hydroxide; the thiohydantoin was separated from other substances by means of a double extraction and then hydrolyzed to form the C-terminal amino acid. In some cases the once degraded peptide chain was subjected again to the procedure in order to reveal the C-penultimate residue of the original peptide. Through application of the method to proteins the C-terminal residues of insulin, ovomucoid, ovalbumin, and bacillomycin B have been revealed. The limitations of the method have been discussed.

Degradative studies on peptides and proteins. Part I. A new method of stepwise degradation of peptides from the end bearing a free amino-group, employing N-acyldithiocarbamates

Degradative studies on peptides and proteins. Part I. A new method of stepwise degradation of peptides from the end bearing a free amino-group, employing N-acyldithiocarbamates

Stepwise degradation of polypeptides from the carboxyl end.

MANY methods have already been described for the selective degradation of peptides from the carboxyl end1. However, the several chemical steps involved in those procedures do not allow their utilization on a micro-scale. Linstead, Shephard and Weedon2 have recently published a study on the decarboxylation of α-N-acylamino-acids in alcoholic media by anodic oxidation into alkoxyalkylamides (acylaminoethers), with a 74–91 per cent yield.