scholarly journals Chemical properties of guinea-pig immunoglobulins γ2G and γM

1970 ◽  
Vol 120 (4) ◽  
pp. 787-795 ◽  
Author(s):  
R. G. Q. Leslie ◽  
S. Cohen
Keyword(s):  
Amino Acid ◽  
Guinea Pig ◽  
Chemical Properties ◽  
Biological Properties ◽  
Extinction Coefficients ◽  
Amino Acid Compositions ◽  
Molecular Weights ◽  
Structural Differences ◽  
Polypeptide Chains

The isolation of guinea-pig immunoglobulins γ1G, γ2G and γM are described and methods for separating the polypeptide chains of each examined. The molecular weights, extinction coefficients and carbohydrate and amino acid compositions of the immunoglobulins and their constituent chains have been analysed. The findings provide a basis for further studies attempting to relate structural differences to distinct biological properties of guinea-pig immunoglobulins.

scholarly journals The polypeptide composition of bovine epidermal α-keratin

1975 ◽  
Vol 151 (3) ◽  
pp. 603-614 ◽  
Author(s):  
P M Steinert ◽  
W W Idler
Keyword(s):  
Amino Acid ◽  
Glutamic Acid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Deae Cellulose ◽  
Cysteine Residues ◽  
Net Charge ◽  
Extinction Coefficients ◽  
Molecular Weights ◽  
Α Helix ◽  
Polypeptide Chains

1. The polypedtide chains that comprise the subunits of the tonofilaments, or the α-keratin component, of bovine epidermis were fractionated by combination of chromatography on DEAE-cellulose and preparative polyacrylamide-gel electrophoresis. 2. The seve polypeptide chains investigated had generalyy similar properties; all contained two residues per molecule of tryptophan and N-acetylserine was the common N-terminal amino acid residue. 3. On the basis of close similarities in α-helix content and amino acid composition, the polypeptide chains were classified into three distinct groups. Each group contained approximately one-third of the total polypeptides on a molar basis. The groups and designated polypeptides chain numbers were: group one, polypeptides 1a and 1b, which had moleculae weights of 58,000, contained about 25% α-helix, 86 glutamic acid and 8 cysteine residues per molecule, but which differed in net charge, extinction coefficients and tyrosine contents; group two, polypeptides 2, 3, and 4, which hadmolecular weights within thewithin the range of 52,00-56,000, contained about 48% α-helix, 54 glutamic acid and 6 cysteine residues per molecule, but which differed in extinction coefficients and tryosine contents; and group, polypeptides 5 and 6, which had molecular weights of 47000-48000, contained about 56% α-helix, 64 glutamic acid and 4 cysteine residues per molecule, but which differed in extinction coefficients and tyrosine contents, it is suggested that none of the chains is a precursor or a degradation product of other polypeptidc chains. 5. It is concluded that bovine epidermal α-keratin consists of a heterogeneous group of similar polypeptide chains.

scholarly journals A comparison of the physical and chemical properties of four cytochromes c from Azotobacter vinelandii

1973 ◽  
Vol 135 (4) ◽  
pp. 617-630 ◽  
Author(s):  
Wilbur H. Campbell ◽  
William H. Orme-Johnson ◽  
Robert H. Burris
Keyword(s):  
Amino Acid ◽  
Spectral Properties ◽  
Azotobacter Vinelandii ◽  
Chemical Properties ◽  
Protein Cleavage ◽  
Separation And Purification ◽  
Amino Acid Compositions ◽  
Molecular Weights ◽  
Cytochromes C ◽  
Isoelectric Points

1. A modified method for the separation and purification of four cytochromes c from Azotobacter vinelandii is described. Two new cytochromes c have been purified and are designated cytochromes c(551) and c(555). 2. Additional evidence is presented to establish the dihaem nature of cytochrome c4. Ultracentrifugation data indicated similar molecular weights for the native and the denatured protein. Cleavage with CNBr yielded seven peptides; the amino acid compositions of the purified peptides were determined. Only one haem peptide was recovered. 3. Cytochromes c(551) and c(555) were characterized as acidic proteins of molecular weights about 12000. The spectral properties, isoelectric points, ‘maps’ of peptides from CNBr cleavage and amino acid compositions were determined for these two proteins. 4. The spectral properties, isoelectric points, molecular weights, CNBr peptide ‘maps’, amino acid compositions, relative oxidation–reduction potentials and e.p.r. (electron-paramagnetic-resonance) spectra of the four cytochromes c were compared. Cytochrome c4 and cytochrome c(551) appear to be distinct proteins. The distinction between cytochromes c5 and c(555) was not as clear, and our data are inadequate to establish firmly that they are distinct proteins. 5. The dihaem nature of cytochrome c4 is evident in its e.p.r. spectrum. The e.p.r. spectra are similar to the spectra of mammalian cytochromes c.

Effect of extractant and molecular size on the optical and chemical properties of soil humic acids

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 229 ◽  
Author(s):  
JHA Butler ◽  
JN Ladd
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Humic Acids ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Molecular Size ◽  
Carboxyl Content ◽  
Peptide Bonds ◽  
Molecular Weights ◽  
Amino Acid Contents

Humic acids extracted from soil with sodium pyrophosphate have greater proportions of lower molecular weight material, less acid-hydrolysable amino acid nitrogen contents, but greater carboxyl contents and extinction values (260 and 450 nm) than humic acids extracted subsequently from the same sample with alkali. Humic acids extracted with alkali from fresh soil samples have intermediate values. Extinction values at 260 nm are directly correlated with carboxyl contents for a given soil. Different crop histories have no significant effect on the measured properties of the extracted humic acids. An alkali-extracted humic acid has been fractionated by gel filtration into seven fractions of different nominal molecular weight ranges. As the molecular weights of the fractions increase, both aliphatic C-H (based on infrared absorption at 2900 cm-1) and acid-hydrolysable amino acid contents increase, whereas extinction values at 260 nm and carboxyl contents decrease. The infrared spectra of the high molecular weight fractions have peaks at 1650 and 1510 cm-1 which correlate with acid-hydrolysable amino acid contents and which correspond to amide I and II bands of peptide bonds. Alkaline hydrolysis to split peptide bonds eliminates both these peaks. The spectra also have peaks at 1720 and 1210 cm-1 which correlate with the carboxyl content.

scholarly journals α-Crystallin. Fractionation of subunits and sequence studies on an isolated polypeptide

1971 ◽  
Vol 124 (2) ◽  
pp. 345-355 ◽  
Author(s):  
Robert C. Augusteyn ◽  
Abraham Spector
Keyword(s):  
Amino Acid ◽  
Gel Electrophoresis ◽  
Cyanogen Bromide ◽  
Sodium Dodecyl ◽  
Deae Cellulose ◽  
Iodoacetic Acid ◽  
Cysteine Residue ◽  
Terminal Sequence ◽  
Amino Acid Compositions ◽  
Molecular Weights

α-Crystallin was carboxymethylated with radioactive iodoacetic acid in the presence of 7.6m-urea and then separated into six major fractions by chromatography on DEAE-cellulose in 7m-urea. Based on the amino acid compositions, specific radioactivities and sodium dodecyl sulphate–gel electrophoresis of the fractions, it was concluded that α-crystallin contains at least four different subunits: DU1A and DU1B, containing no cysteine; a third component represented by DU2B and DU3 containing one cysteine one cysteine residue per subunit; and DU4, which probably contains two residues of cysteine per subunit. Subunit DU1A was shown to be of sufficient purity for sequence studies. Cyanogen bromide cleavage yielded two peptides, CB-1 and CB-2, in approximately equal amounts as expected. The sum of the molecular weights and amino acid compositions of the peptides were both in excellent agreement with the results obtained for subunit DU1A. The amino acid sequence of the first sixteen residues of peptide CB-1 is: Ser-Leu-Thr-Lys-Asp-Phe-Asp-Glu-Val-Asn-Ile-Asp-Val-Ser-His-Phe-. The sequence of the first seventeen residues of peptide CB-2 is: Asp-Ile-Ala-Ile-Ser-His-Pro-Trp-Ile-Arg-Pro-Ser-Phe-Phe-Glu-Phe-His-. The N-terminal sequence of subunit DU1A was shown to be N-acetylmethionine followed by peptide CB-2.

scholarly journals Biochemical characterization of a second family of human Ia molecules, HLA-DS, equivalent to murine I-A subregion molecules.

1982 ◽  
Vol 156 (2) ◽  
pp. 550-566 ◽  
Author(s):  
S M Goyert ◽  
J E Shively ◽  
J Silver
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Amino Acid Sequence Identity ◽  
Biochemical Characterization ◽  
Amino Acid Sequence Homology ◽  
Molecular Weights ◽  
Hla Dr ◽  
D Region ◽  
Polypeptide Chains

In mice, two families of structurally distinct Ia molecules, one designated I-A and the other I-E, have been identified and characterized. The HLA-DR molecules represent one family of human Ia molecules equivalent to the murine I-E molecules on the basis of amino acid sequence homology. We describe the isolation and biochemical characterization of a second family of human Ia molecules, designated HLA-DS for second D-region locus, equivalent to the murine I-A molecules. The human HLA-DS molecules consist of two polypeptide chains, DS alpha (37,000 mol wt) and DS beta (29,000 mol wt), with 73% amino acid sequence identity to the murine I-A molecules. Furthermore, the HLA-DS molecules are closely linked genetically to HLA-DR molecules, a situation analogous to that observed in mice. The similarity in molecular weights of the DR and DS molecules might explain why others have failed to identify the latter in man.

scholarly journals Isolation and characterization of phytoferritin from pea (Pisum sativum) and Lentil (Lens esculenta)

1978 ◽  
Vol 171 (2) ◽  
pp. 349-356 ◽  
Author(s):  
R R Crichton ◽  
Y Ponce-Ortiz ◽  
M H J Koch ◽  
R Parfait ◽  
H B Stuhrmann
Keyword(s):  
Amino Acid ◽  
Pisum Sativum ◽  
Quaternary Structure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Lens Esculenta ◽  
Molecular Weights ◽  
Isolation And Characterization ◽  
Angle Scattering ◽  
Scattering Study ◽  
Polypeptide Chains

Ferritin was isolated from the seeds of pea (Pisum sativum) and lentil (Lens esculenta). The homogeneity of the phytoferritins was established by polyacrylamide-gel electrophoresis. The subunit molecular weights were respectively 20 300 and 21 400 for hte pea and lentil proteins. A neutron low-angle scattering study established the molecular weight of the oligomer as 480 000 for pea apoferritin and 510 000 for lentil apoferritin. Although the quaternary structure of 24 polypeptide chains is preserved, the phytoferritins have a larger cavity in the interior than mammalian ferritins and can thus potentially store 1.2-1.4 times as much iron. The amino acid composition of the phytoferritins show some similarities to those of mammalian apoferritins; tryptic ‘fingerprinting’ reveals that there are many differences in the amino acid sequence of plant and mammalian apoferritins.

Sign in / Sign up

Export Citation Format

Share Document