The Nature of the Chelate Structures Formed by Copper(II) and Ovalbumin in the Biuret Reaction

1963 ◽  
Vol 16 (6) ◽  
pp. 989 ◽  
Author(s):  
AC Jennings
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Alkaline Solution ◽  
Polypeptide Chain ◽  
Chemical Reactivity ◽  
Spectrophotometric Study ◽  
Low Molecular Weight ◽  
Amino Acid Residues ◽  
Heterogeneous Mixture

A spectrophotometric study was made of the interaction, in alkaline solution, of copper(II) with ovalbumin and several ligands of low molecular weight at several different atomic ratios of nitrogen/copper. The results indicate that the absorbance and chemical reactivity of the ovalbumin-copper(II) complex cannot be attributed to the presence of one particular chelate structure. It is suggested that the ovalbumin-copper(II) complex is a heterogeneous mixture of chelate structures in which the copper(II) is bonded to oxygen (in the enolate form) and nitrogen atoms in the several different combinations possible within the same polypeptide chain. It is also suggested that the actual arrangement of bonds in any one chelate structure is probably determined by both the nature of the amino acid residues and the configuration of the ovalbumin molecule in the immediate vicinity.

scholarly journals Studies of the limited degradation of mucus glycoproteins. The effect of dilute hydrogen peroxide

1983 ◽  
Vol 211 (2) ◽  
pp. 323-332 ◽  
Author(s):  
J M Creeth ◽  
B Cooper ◽  
A S R Donald ◽  
J R Clamp
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Simple Structure ◽  
Peptide Bond ◽  
Low Molecular Weight ◽  
Amino Acid Residues ◽  
Oligosaccharide Moiety ◽  
Small Gain ◽  
Mucus Glycoproteins

1. The action of dilute H2O2 on a series of ovarian-cyst glycoproteins and glycopolypeptides was investigated. 2. Both native glycoproteins and the glycopolypeptides were carbohydrate-rich, of relatively low molecular weight and of simple structure. 3. At pH 5.6 and 37 degrees C, exposure to H2O2 for a limited time brought about a partial degradation, the molecular weight being decreased by 2-4-fold. 4. Carbohydrate analysis showed very little change in the oligosaccharide moiety, apart from a small decrease in sialic acid in some samples. 5. Amino acid analysis showed minor changes in serine, threonine and proline contents, but almost total loss of histidine. Concomitantly, there was a small gain in aspartic acid. 6. Myosin, examined at both pH 5.7 and 6.7, exhibited generally similar behaviour, there being losses of other amino acid residues as well as histidine: the viscosity was decreased to a low value, and a range of peptides of widely varying size was produced. 7. It is suggested that attack on the histidine residue, with partial conversion into aspartic acid, is accompanied by scission of the histidyl peptide bond.

The amino acid sequence of wheat β-purothionin

1976 ◽  
Vol 54 (10) ◽  
pp. 835-842 ◽  
Author(s):  
A. S. Mak ◽  
B. L. Jones
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Primary Structure ◽  
Basic Protein ◽  
Viscum Album ◽  
Low Molecular Weight ◽  
Amino Acid Residues ◽  
Basic Proteins ◽  
Considerable Homology

The complete amino acid sequence of β-purothionin, a low molecular weight, very basic, protein isolated from wheat endosperm material, has been determined. β-purothionin is toxic to some bacteria, to yeasts, and to animals when injected. The protein contains 45 amino acid residues and has a molecular weight of 4913. The 8 cysteine and 10 basic residues are distributed throughout the molecule. The primary structure of the protein shows considerable homology to those of the viscotoxins, which are toxic, small, basic proteins found in the leaves and stems of European mistletoe (Viscum album L.).

scholarly journals Определение казеина в молоке

2021 ◽  
pp. 32-38
Author(s):  
L. M. Kalimoldina ◽  
A. P. Abdykarimova ◽  
A. N. Alipbaev
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Protein Content ◽  
Genetic Variants ◽  
Polypeptide Chain ◽  
Goat Milk ◽  
Cow Milk ◽  
Amino Acid Residues ◽  
Milk Samples ◽  
Main Components

In the present study the precipitation of casein from the various milk samples such as cow milk, goat milk were studied. The technique of precipitation of casein is used to predict the protein content in the milk samples. It was found that the main components of casein have genetic variants that differ in several amino acid residues. These proteins have a molecular weight of about 20 thousand, an isoelectric point of about 4.7, contain an increased amount of proline (the polypeptide chain has a b-structure) and are resistant to denaturants.

THE HETEROGENEITY OF GAMMA-GLOBULIN IN POST-EXERCISE URINE

1964 ◽  
Vol 42 (7) ◽  
pp. 1065-1097 ◽  
Author(s):  
M. H. Freedman ◽  
G. E. Connell
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Polypeptide Chain ◽  
Gel Filtration ◽  
Low Molecular Weight ◽  
Starch Gel Electrophoresis ◽  
Single Individual ◽  
Post Exercise ◽  
Γ Globulins ◽  
Normal Urine

Post-exercise urine was collected and the protein was precipitated with ammonium sulphate. The γ-globulin was separated from other urinary proteins by preparative starch block electrophoresis. The γ-globulin was then separated by gel filtration into two fractions, the faster one consisting mainly of 7 S γ-globulin while the slower one contained "low molecular weight" γ-globulin sedimenting at 3.5 S. The low molecular weight γ-globulins were further fractionated on CM-Sephadex to yield four fractions. Each of the chromatographic fractions was shown to be heterogeneous by starch gel electrophoresis at pH 4. The same degree of heterogeneity was observed in preparations of pooled urinary γ-globulin and γ-globulin from a single individual. The two major electrophoretic components of each chromatographic fraction formed precipitates in agar diffusion tests with antiserum to 7 S γ-globulin and to the L-polypeptide chain of 7 S γ-globulin. Two chromatographic fractions reacted with antiserum to the H-polypeptide chain of 7 S γ-globulin. All of the fractions failed to react with antiserum to β2A-globulin and β2M-globulin. Amino acid analysis showed distinct differences among the chromatographic fractions. One of the fractions closely resembled the L-chain of 7 S plasma γ-globulin with respect to amino acid composition. After reduction of disulphide bonds and alkylation most of the urinary γ-globulin resembles L-chain in electrophoretic behavior. The γ-globulins of post-exercise urine were found to be qualitatively similar to the γ-globulins of normal urine but post-exercise γ-globulins were present quantitatively in much larger amounts.

Amino acid sequence of cyanogen bromide fragment CB5 of human hemopexin

1989 ◽  
Vol 54 (3) ◽  
pp. 803-810 ◽  
Author(s):  
Ivan Kluh ◽  
Ladislav Morávek ◽  
Manfred Pavlík
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Acid Hydrolysis ◽  
Cyanogen Bromide ◽  
Polypeptide Chain ◽  
Amino Acid Residues ◽  
Mild Acid Hydrolysis ◽  
Methionine Residue ◽  
Cyanogen Bromide Fragment ◽  
Mild Acid

Cyanogen bromide fragment CB5 represents the region of the polypeptide chain of hemopexin between the fourth and fifth methionine residue (residues 232-352). It contains 120 amino acid residues in the following sequence: Arg-Cys-Ser-Pro-His-Leu-Val-Leu-Ser-Ala-Leu-Thr-Ser-Asp-Asn-His-Gly-Ala-Thr-Tyr-Ala-Phe-Ser-Gly-Thr-His-Tyr-Trp-Arg-Leu-Asp-Thr-Ser-Arg-Asp-Gly-Trp-His-Ser-Trp-Pro-Ile-Ala-His-Gln-Trp-Pro-Gln-Gly-Pro-Ser-Ala-Val-Asp-Ala-Ala-Phe-Ser-Trp-Glu-Glu-Lys-Leu-Tyr-Leu-Val-Gln-Gly-Thr-Gln-Val-Tyr-Val-Phe-Leu-Thr-Lys-Gly-Gly-Tyr-Thr-Leu-Val-Ser-Gly-Tyr-Pro-Lys-Arg-Leu-Glu-Lys-Glu-Val-Gly-Thr-Pro-His-Gly-Ile-Ile-Leu-Asp-Ser-Val-Asp-Ala-Ala-Phe-Ile-Cys-Pro-Gly-Ser-Ser-Arg-Leu-His-Ile-Met. The sequence was derived from the data on peptides prepared by cleavage of fragment CB5 by mild acid hydrolysis, by trypsin and chymotrypsin.

scholarly journals The complete amino acid sequence of the low molecular weight cytosolic acid phosphatase

1989 ◽  
Vol 264 (5) ◽  
pp. 2560-2567
Author(s):  
G Camici ◽  
G Manao ◽  
G Cappugi ◽  
A Modesti ◽  
M Stefani ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Acid Phosphatase ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Low Molecular Weight ◽  
Complete Amino Acid Sequence

Hygroscopic behavior and chemical reactivity of aerosols generated from mixture solutions of low molecular weight dicarboxylic acids and NaCl

2021 ◽  
Author(s):  
Xue Li ◽  
Li Wu ◽  
Ji-Soo Lee ◽  
Chul-Un Ro
Keyword(s):  
Molecular Weight ◽  
Chemical Reactivity ◽  
Dicarboxylic Acids ◽  
Sea Spray ◽  
Low Molecular Weight ◽  
Hygroscopic Behavior

Ambient sea spray aerosols (SSAs) have been reported to undergo reactions with low molecular weight dicarboxylic acids (LMW DCAs). In the present study, the hygroscopic behavior of aerosols generated from...

scholarly journals Characterization of Trypsin Inhibitor in Florunner Peanut Seeds (Arachis hypogaea L.)1

1988 ◽  
Vol 15 (2) ◽  
pp. 81-84 ◽  
Author(s):  
E. M. Ahmed ◽  
J. A. Applewhite
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Arachis Hypogaea ◽  
Trypsin Inhibitor ◽  
Low Molecular Weight ◽  
Arachis Hypogaea L ◽  
Amino Acid Profiles ◽  
Low Levels

Abstract Florunner peanut seeds contained five trypsin isoinhibitors. Amino acid profiles of the trypsin inhibitors fraction showed high levels of aspartic acid, half-cystine and serine and low levels of histidine and tyrosine. The molecular weight of the inhibitor was 8.3 KDa. The presence of multiforms of this inhibitor, its low molecular weight and the high amount of half-cystine indicate that peanut trypsin inhibitor is of the Bowman-Birk type.

scholarly journals Bile-pigment formation from different leghaemoglobins. Methine-bridge specificity of coupled oxidation

1978 ◽  
Vol 176 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Päivi Lehtovaara ◽  
Ulla Perttilä
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Broad Bean ◽  
Amino Acid Sequences ◽  
Second Step ◽  
Bile Pigment ◽  
Site Specificity ◽  
Amino Acid Residues ◽  
Reaction Step ◽  
Pigment Formation

The coupled oxidation of leghaemoglobins with O2 and ascorbate yielded oxyleghaemoglobin in the first reaction step, and the second step was the degradation of haem characterized by an A675 increase. Leghaemoglobins were degraded to biliverdin isomers specifically, depending on the structure of the protein. The main leghaemoglobin components of Glycine (soya bean) and Phaseolus (kidney bean) were degraded to biliverdin mixtures containing about 50% of the β-form, about 30% of the α-form and about 20% of the δ-isomer, whereas the leghaemoglobin I components of Vicia (broad bean) and Pisum (pea) were degraded almost exclusively to the β-isomer, with traces of the α-isomer. The amino acid sequences of Glycine and Phaseolus leghaemoglobins resemble each other, as do those of Vicia and Pisum. The site specificity of bile-pigment formation from leghaemoglobins can be tentatively explained by specific differences in the amino acid sequences at those regions of the polypeptide chain that are in the vicinity of the appropriate methine bridges. The ligand-binding site in different leghaemoglobins may be outlined on the basis of the present results, supposing that the haem is degraded when a reduction product of haem-bound O2 reacts with a methine bridge of the haem, and that the bridge specificity is regulated by hindering amino acid residues that determine the location of the bound O2. The residue phenylalanine-CD1 appears to be further away from the haem plane or in a markedly more flexible position in leghaemoglobins than in mammalian globins. The haem-bound oxygen atom B, in Fe–O(A)–O(B), seems to be free to rotate in all directions except that of the γ-bridge in Glycine and Phaseolus leghaemoglobins, but its position in Vicia and Pisum leghaemoglobin I might be restricted to the direction of the β-methine bridge.

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