scholarly journals Mechanisms of heat damage in proteins

1970 ◽  
Vol 24 (1) ◽  
pp. 313-329 ◽  
Author(s):  
J. Bjarnason ◽  
K. J. Carpenter
Keyword(s):  
Amino Acids ◽  
Main Reaction ◽  
Amino Group ◽  
Amino Groups ◽  
Sulphur Compounds ◽  
Plasma Albumin ◽  
Small Loss ◽  
Bovine Plasma ◽  
Carboxylic Groups ◽  
Ammonia Liberation

1. Bovine plasma albumin (BPA) containing approximately 14% moisture, when heated for 27 h at 115° suffered an appreciable loss of cystine and a small loss of lysine; at 145° all the amino acids except glutamic acid and those with paraffin side-chains, showed considerable losses. Isoleucine also showed some loss through racemization to alloisoleucine.2. BPA heated at 115° evolved H2S; at 145° other sulphur compounds were released as well, all coming from the breakdown of cystine. Possible mechanisms for this are discussed.3. Ammonia was also liberated from BPA heated at 115°. The degree of correlation of lysine binding in different proteins with ammonia liberation and amide changes has led us to suggest that the main reaction of ε-amino lysine groups is with amide groups of asparagine and glutamine. Reaction of ε-amino groups with carboxylic groups is thought to be less important.4. Model experiments have shown that a reaction between amide groups and the e-amino group of lysine in proteins can occur at practical drying temperatures.5. Reactions of the ε-amino group of lysine with destruction products of cystine is also considered to be partially responsible for the lysine binding in heated proteins.

Sporidesmins. XIV. Modifications to the Opened -S-S- Bridge of Sporidesmin for Coupling to Proteins by Transacylation

1975 ◽  
Vol 28 (9) ◽  
pp. 2043 ◽  
Author(s):  
J Ronaldson
Keyword(s):  
Mass Spectrum ◽  
Serum Albumin ◽  
Thiol Group ◽  
Rabbit Serum ◽  
Amino Groups ◽  
Plasma Albumin ◽  
Bovine Plasma ◽  
Conventional Tests

Alkylation of the opened -S-S- bridge of sporidesmin formed diethyl secosporidesmin-S,S?-diacetate(3), dimethyl secosporidesmin-S,S?- diacetate (4), methyl 3-mercaptosecosporidesmin-11a-S-acetate (5) and methyl 11a-mercaptosecosporidesmin-3-S-acetate (6) which were condensed with ε-amino groups of poly(L-lysine), bovine plasma albumin and rabbit serum albumin. The thiol group in compound (6) could not be demonstrated by conventional tests but its presence was established by its mass spectrum.

scholarly journals o-Quinones formed in plant extracts. Their reactions with amino acids and peptides

1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plant Extracts ◽  
Thiol Group ◽  
Amino Group ◽  
Amino Groups ◽  
Terminal Amino Acid ◽  
Secondary Reactions ◽  
Terminal Amino ◽  
Group 5

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.

Increased Resistance of Peptides to Serum Proteases by Modification of their Amino Groups

2003 ◽  
Vol 58 (7-8) ◽  
pp. 558-561 ◽  
Author(s):  
Rossella Galati ◽  
Alessandra Verdina ◽  
Giuliana Falasca ◽  
Alberto Chersi
Keyword(s):  
Amino Acids ◽  
Proteolytic Enzymes ◽  
Living Organism ◽  
Amino Group ◽  
Amino Groups ◽  
Protein Fragments ◽  
Beta Alanine ◽  
Synthetic Protein ◽  
In Vivo Tests

Abstract The ability of synthetic protein fragments to survive the degradative action of aminopeptidases and serum proteolytic enzymes can be remarkably enhanced by slight modifications at their N-terminal alpha-amino group. This can be achieved by addition of beta-alanine or amino acids of the d-configuration, amino acids which are seldom found in a living organism. These modifications do scarcely modify the chemical and physical properties of the peptides, and should be preferrred, especially for in vivo tests, to drastic alterations of peptides as produced by dinitrophenylation or dansylation of the amino groups.

scholarly journals The measurement of amino groups in proteins and peptides

1971 ◽  
Vol 124 (3) ◽  
pp. 581-590 ◽  
Author(s):  
R Fields
Keyword(s):  
Amino Acids ◽  
Room Temperature ◽  
Thiol Group ◽  
Amino Group ◽  
Thiol Groups ◽  
Amino Groups ◽  
Model Compounds ◽  
Time Required ◽  
Short Time ◽  
Proteins And Peptides

A technique is examined for determining amino groups with 2,4,6-trinitrobenzenesulphonic acid, in which the extinction at 420nm of sulphite complexes of the trinitrophenylated amino groups is measured. The sensitivity of the method is 5–200nmol of amino group. The method is especially suitable for checking the extent of blocking or unblocking of amino groups in proteins and peptides, owing to the short time required for reaction (5min at room temperature). The reaction of the reagent with thiol groups has been studied and was found to proceed 30–50 times faster than with ∈-amino groups of model compounds. The ∈420 of a trinitrophenylated thiol group was found to be 2250m-1·cm-1. The reaction with several amino acids, peptides and proteins is presented. The ∈420 of a typical α-amino group was found to be 22000m-1·cm-1 and that of an ∈-amino group, 19200m-1·cm-1. Difficulties inherent in the analysis of constituent amino group reactions in proteins are discussed.

scholarly journals Glutamine: precursor or nitrogen donor for citrulline synthesis?

2010 ◽  
Vol 299 (1) ◽  
pp. E69-E79 ◽  
Author(s):  
Juan C. Marini ◽  
Inka Cajo Didelija ◽  
Leticia Castillo ◽  
Brendan Lee
Keyword(s):  
Amino Acids ◽  
Current Literature ◽  
Ammonium Acetate ◽  
Carbon Skeleton ◽  
Amino Group ◽  
Amino Groups ◽  
Amido Group ◽  
Nitrogen Donor ◽  
Citrulline Synthesis

Although glutamine is considered the main precursor for citrulline synthesis, the current literature does not differentiate between the contribution of glutamine carbon skeleton vs. nonspecific nitrogen (i.e., ammonia) and carbon derived from glutamine oxidation. To elucidate the role of glutamine and nonspecific nitrogen in the synthesis of citrulline, l-[2-15N]- and l-[5-15N]glutamine and 15N-ammonium acetate were infused intragastrically in mice. The amino group of glutamine labeled the three nitrogen groups of citrulline almost equally. The amido group and ammonium acetate labeled the ureido and amino groups of citrulline, but not the δ-nitrogen. D5-glutamine also infused in this arm of the study, which traces the carbon skeleton of glutamine, was utilized poorly, accounting for only 0.2–0.4% of the circulating citrulline. Dietary glutamine nitrogen (both N groups) incorporation was 25-fold higher than the incorporation of its carbon skeleton into citrulline. To investigate the relative contributions of the carbon skeleton and nonspecific carbon of glutamine, arginine, and proline to citrulline synthesis, U-13Cn tracers of these amino acids were infused intragastrically. Dietary arginine was the main precursor for citrulline synthesis, accounting for ∼40% of the circulating citrulline. Proline contribution was minor (3.4%), and glutamine was negligible (0.4%). However, the glutamine tracer resulted in a higher enrichment in the ureido group, indicating incorporation of nonspecific carbon from glutamine oxidation into carbamylphosphate used for citrulline synthesis. In conclusion, dietary glutamine is a poor carbon skeleton precursor for the synthesis of citrulline, although it contributes both nonspecific nitrogen and carbon to citrulline synthesis.

scholarly journals The reaction of 2,4,6-trinitrobenzenesulphonic acid with amino acids, peptides and proteins

1968 ◽  
Vol 108 (3) ◽  
pp. 383-391 ◽  
Author(s):  
R. B. Freedman ◽  
G. K. Radda
Keyword(s):  
Amino Acids ◽  
Glutamate Dehydrogenase ◽  
Free Amino ◽  
Reactive Species ◽  
Second Order ◽  
Amino Group ◽  
Exponential Rate ◽  
Amino Groups ◽  
Sh Group ◽  
Kinetics Of

1. The kinetics of the reaction of 2,4,6-trinitrobenzenesulphonic acid with various amino acids, peptides and proteins were studied by spectrophotometry. 2. The reaction of the α- and ∈-amino groups in simple amino acids was found to be second-order, and the unprotonated amino group was shown to be the reactive species. 3. By allowing for the concentration of unreactive −NH3+ group, intrinsic reactivities for the free amino groups were derived and shown to be correlated with the basicities. 4. The SH group of N-acetylcysteine was found to be more reactive to 2,4,6-trinitrobenzenesulphonic acid than most amino groups. 5. The reactions of insulin, chymotrypsinogen and ribonuclease with 2,4,6-trinitrobenzenesulphonic acid were analysed in terms of three exponential rate curves, each referring to one or more amino groups of the proteins. 6. The reaction of lysozyme with 2,4,6-trinitrobenzenesulphonic acid was found to display an acceleration effect. 7. From the reaction of 2,4,6-trinitrobenzenesulphonic acid with glutamate dehydrogenase at several enzyme concentrations, it was possible to discern two sets of amino groups of different reactivity, and to show that the number of groups in each set was decreased by aggregation of the enzyme.

scholarly journals NMR spectroscopy of Cu(II) complexes with acrylamide and sodium acrylate copolymer and ω-amino acids

2021 ◽  
pp. 85-98
Author(s):  
Дмитрий Леонович Кудрявский ◽  
Елена Константиновна Фомина ◽  
Людмила Юльевна Тычинская ◽  
Евгений Доминикович Скаковский ◽  
Светлана Евгеньевна Богушевич
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Aminocaproic Acid ◽  
Aminobutyric Acid ◽  
Molar Ratio ◽  
Sodium Acrylate ◽  
Amino Groups ◽  
Acrylate Copolymer ◽  
Carboxylic Groups

Macromolecular complexes of acrylamide and sodium acrylate copolymer with microelements, including Cu(II), may form at preparation of crop protection and stimulation compositions, where the copolymer serves as an adhesive, water-retaining and film-forming agent. Preparations for crop production may also contain amino acids that protect plants under stressful conditions (cold, dry, etc.). Carboxylic groups of copolymer, carboxylic and amino groups of amino acids may be involved in mixed Cu(II) ions complexes formation. Number of methylene groups separating carboxylic and amino group of amino acids affects its ability to form a stable chelate cycle and, therefore, ligand composition of mixed Cu(II) ions complexes with acrylamide and sodium acrylate copolymer and amino acid. This work is aimed at determining the ligand composition of mixed macromolecular Cu(II) ion complexes with acrylamide and sodium acrylate copolymer and ω-amino acids (β-alanine, γ-aminobutyric acid, ε-aminocaproic acid). 13C and 1H NMR spectroscopy was used to clarify complexes composition. A complex where carboxylic groups of amino acids are ligands has been found to form in aqueous solutions of Cu(II) ions and ω-amino acid (β-alanine, γ-aminobutyric acid, ε-aminocaproic acid) at molar ratio of Cu(II) ions – amino acid equal to 1 : 6. A chelate complex where both carboxylic and amino groups of β-alanine are involved in coordination has been discovered to form in the solution containing Cu(II) ions, β-alanine, as well as acrylamide and sodium acrylate copolymer at molar ratio of Cu(II) – β-alanine – copolymer COO− equal to 1 : 6 : 30. Carboxylic groups of copolymer participate in complex formation as well. Carboxylic groups of both amino acids and the copolymer have been shown to participate in complex formation in aqueous solutions containing Cu(II) ions, either γ-aminobutyric or ε-aminokaproic acid and also acrylamide and sodium acrylate copolymer.

DEGRADATION BY HYDRAZINE OF BOVINE PLASMA ALBUMIN AND LYSOZYME

1960 ◽  
Vol 38 (1) ◽  
pp. 715-726 ◽  
Author(s):  
Madeleine Champagne ◽  
David B. Smith
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Hydrazine Hydrate ◽  
Plasma Albumin ◽  
Bovine Plasma ◽  
Terminal Amino

The effect of hydrazine and hydrazine hydrate on bovine plasma albumin and lysozyme at 5° and 20 °C has been studied by viscosity, sedimentation, and molecular weight measurements. The appearance of new N-terminal amino acids and peptides has been demonstrated. The effect of these reagents is an initial unfolding of the molecule followed by slow, non-random fission to smaller particles.

DEGRADATION BY HYDRAZINE OF BOVINE PLASMA ALBUMIN AND LYSOZYME

1960 ◽  
Vol 38 (7) ◽  
pp. 715-726 ◽  
Author(s):  
Madeleine Champagne ◽  
David B. Smith
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Hydrazine Hydrate ◽  
Plasma Albumin ◽  
Bovine Plasma ◽  
Terminal Amino

The effect of hydrazine and hydrazine hydrate on bovine plasma albumin and lysozyme at 5° and 20 °C has been studied by viscosity, sedimentation, and molecular weight measurements. The appearance of new N-terminal amino acids and peptides has been demonstrated. The effect of these reagents is an initial unfolding of the molecule followed by slow, non-random fission to smaller particles.

Bovine Platelet Proteins

1969 ◽  
Vol 21 (03) ◽  
pp. 409-418 ◽  
Author(s):  
S Łopaciuk ◽  
N. O Solum
Keyword(s):  
Bovine Serum ◽  
Protein Composition ◽  
Disc Electrophoresis ◽  
Plasma Fibrinogen ◽  
Plasma Albumin ◽  
Precipitin Line ◽  
Bovine Plasma ◽  
Platelet Proteins

Summary1. The protein composition of bovine platelet extracts has been investigated by immunoelectrophoresis and polyacrylamide disc electrophoresis. The information obtained is discussed as a basis for study on platelet fibrinogen.2. With antiserum to platelet proteins 11 precipitin lines were observed 3 of which corresponded electrophoretically to plasma albumin, fibrinogen and γ-globulin. These lines were not seen using the same antiserum absorbed with bovine plasma. The 8 additional lines were still present indicating that they represented specific platelet components. Antiserum to plasma produced the 3 above-mentioned lines, but no others.3. With antiserum to purified bovine plasma fibrinogen 3 precipitin lines were observed. The fibrinogen line was the dominant one. The 2 additional lines did not disappear by absorption of the antiserum with bovine serum nor by incubation of the extracts with thrombin. The latter treatment totally removed the fibrinogen line.4. A non-fibrinogen precipitin line, observed only with the antiserum to platelet extract and positioned in the β2-globulin region, disappeared by the incubation of platelet extracts with thrombin.

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