Isoelectric focusing electrophoresis of protein-ligand conjugates: effect of the degree of substitution

1991 ◽  
Vol 37 (1) ◽  
pp. 87-90 ◽  
Author(s):  
Mlnas S Barbarakis ◽  
Leonldas G Bachas
Keyword(s):  
Amino Acid ◽  
Theoretical Model ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Isoelectric Focusing ◽  
Isoelectric Point ◽  
Calibration Curve ◽  
Degree Of Substitution

Abstract The degree of substitution of protein-ligand conjugates can be determined from the change of the isoelectric point (pI) of the protein when ligand molecules are attached to its surface. Specifically, the pI values of conjugates with known degrees of substitution are obtained by isoelectric focusing electrophoresis and are used to generate a calibration curve that relates these two variables. The shape of the curve is sigmoidal and can be predicted by a theoretical model that takes into account the degree of substitution and the amino acid composition of the protein. By using such a calibration curve, one may estimate the degree of substitution of a given protein-ligand conjugate from its pI value. The applicability of the method is demonstrated with conjugates of pyridoxal 5-phosphate and avidin.

Structural study on liver gelactin

1984 ◽  
Vol 62 (11) ◽  
pp. 1072-1075 ◽  
Author(s):  
Julian Gruda ◽  
Hélène-Marie Thérien
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Structural Study ◽  
Isoelectric Focusing ◽  
Isoelectric Point ◽  
Gel Filtration ◽  
Rabbit Liver

Electron microscopy, ultracentrifugation, gel filtration, and isoelectric focusing were carried out with gelactin, an actin-gelling protein from rabbit liver. Gelactin is a dimeric acidic protein (isoelectric point (pI) = 5.45), with a molecular weight of 190 000, a Svedberg constant of 6.25, and a Stoke's radius and length of 7.0 and 28 nm, respectively. While different from α-actinin by pI and amino acid composition, gelactin belongs by its dimensions to the class of α-actinins.

scholarly journals AMINO ACID COMPOSITION AND ELECTROPHORETIC PROPERTIES OF HYPERTENSIN I

1955 ◽  
Vol 102 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Leonard T. Skeggs ◽  
Walton H. Marsh ◽  
Joseph R. Kahn ◽  
Norman P. Shumway
Keyword(s):  
Amino Acids ◽  
Quantitative Analysis ◽  
Amino Acid ◽  
Ion Exchange ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Isoelectric Point ◽  
Column Chromatography ◽  
Isoleucine Leucine ◽  
Ion Exchange Column

A preparation of hypertensin I was purified by countercurrent distribution and was shown to migrate as a single component in starch blocks at pH 9.3 and 4.2. It had an isoelectric point of 7.7. Quantitative analysis by ion exchange column chromatography showed eight amino acids in approximately unimolar proportion: aspartic, proline, valine, isoleucine, leucine, tyrosine, phenylalanine, and arginine. There were in addition two moles of histidine.

scholarly journals Purification and Properties of Staphylocoagulase

1975 ◽  
Author(s):  
A.D. Muller ◽  
B. M. Bas ◽  
H. C. Hemker
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Aspartic Acid ◽  
Acid Composition ◽  
Isoelectric Point ◽  
Terminal Amino Acid ◽  
Purification And Properties ◽  
Terminal Amino

Staphylocoagulase, an exoprotein of coagulase positive staphylocoagulase, has been purified to a state in which only trace amounts of contaminating proteins are detectable.Purification was more than 35,000 fold, which is 7 times more than the highest value reported in the literature. The yield was about 15%.Aspartic acid was found as a single N-terminal amino acid in this preparation. The molecular weight is 61,000 and the isoelectric point lies at pH 4.53.The amino acid composition was determined.

scholarly journals Studies on Ovalbumin V. The Amino Acid Composition and Some Properties of Chicken, Duck, and Turkey Ovalbumins

1970 ◽  
Vol 23 (5) ◽  
pp. 1221 ◽  
Author(s):  
MB SmIth ◽  
Joan F Back
Keyword(s):  
Amino Acid ◽  
Amino Acid Composition ◽  
Ammonium Sulphate ◽  
Acid Composition ◽  
Isoelectric Focusing ◽  
Ph Gradient ◽  
Ammonium Sulphate Fractionation

The ovalbumins from chicken, duck, and turkey eggs were prepared by ammonium sulphate fractionation and purified by isoelectric focusing in a pH gradient from 3 to 6. Amino acid analyses show a closer relationship between turkey and chicken ovalbumins than between duck and chicken ovalbumins.

scholarly journals Purification and properties of a proteolytic enzyme from the cercariae of the human trematode parasite Schistosoma mansoni

1982 ◽  
Vol 201 (1) ◽  
pp. 137-144 ◽  
Author(s):  
W J Landsperger ◽  
M A Stirewalt ◽  
M H Dresden
Keyword(s):  
Amino Acid ◽  
Schistosoma Mansoni ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Isoelectric Point ◽  
Proteolytic Enzymes ◽  
Sodium Dodecyl ◽  
Skin Penetration ◽  
Cathepsin G ◽  
Trematode Parasite

Skin penetration by the cercarial stage of the human trematode parasite Schistosoma mansoni is mediated by the secretion of proteolytic enzymes able to digest components of mammalian connective tissues. In the present study the purification of these proteinases from cercarial homogenates is reported. The major proteinase species has a mol. wt. of approx. 25 000 and exists in monomeric form as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. This proteinase has an isoelectric point of 6.0. Studies presented here, with a variety of substrates and inhibitors, confirm previous claims that these proteinases belong to the serine class, and, in addition, suggest that they resemble the vertebrate chymotrypsins rather than trypsins or elastases. However, the amino acid composition of the cercarial proteinase differs significantly from bovine chymotrypsin and from the human leucocyte chymotrypsin-like cathepsin G. The amino-acid-composition differences between these proteinases are consistent with their differences in isoelectric point. In order to obtain an insight into the role of the proteinase in skin penetration, its activity on cartilage proteoglycan monomers and on the isolated peptide backbone of proteoglycan was studied. The results of the present study indicate that the cercarial enzyme catalyses a limited specific digestion of the peptide core.

scholarly journals pIPredict Version 2: New Features and PTM Analysis

2018 ◽  
Vol 1 (2) ◽  
pp. e00009 ◽  
Author(s):  
V.S. Skvortsov ◽  
N.N. Alekseychuk ◽  
Yu.V. Miroshnichenko ◽  
A.V. Rybina
Keyword(s):  
Amino Acid ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Isoelectric Point ◽  
The Other ◽  
2D Electrophoresis ◽  
Chemical Modifications ◽  
Post Translational Modifications ◽  
Pka Values ◽  
Java Application

pIPredict was created as a tool for prediction of the isoelectric point of peptides and proteins. It can also generate virtual 2D electrophoresis maps. The method of pI prediction is based on the Henderson-Hasselbach equation. In a new version the ProMoST and our new scales of pKa values were added. The other added features included: correction of electrophoretic shift by analyzing amino acid composition of proteins and prediction of pI values for proteins with a new set of posttranslational and other chemical modifications. Prediction of pI for proteins with PTM can be used to predict position of modified proteoforms on the virtual 2D electrophoresis map or as the tool of identifying which particular proteoform was observed in the experiment.The program also includes several widely used pKa scales, that can partially calculate values for proteins with some post-translational modifications. pIPredict is created as JAVA application and is freely available at http://www.ibmc.msk.ru/LPCIT/pIPredict.

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