Gel filtration chromatography

Gel-filtration chromatography is a popular and versatile technique that permits the effective separation of proteins and other biological molecules in high yield. Here, the basis of the method is described and typical matrix types are contrasted. The selection of suitable operating conditions and applications of the method are also discussed

A Monomer-to-Trimer Transition of the Human Mitochondrial Transcription Termination Factor (mTERF) Is Associated with a Loss of in Vitro Activity

The human mitochondrial transcription termination factor (mTERF) is a nuclear-encoded 39-kDa protein that recognizes a mtDNA segment within the mitochondrial tRNALeu(UUR) gene immediately adjacent to and downstream of the 16 S rRNA gene. Binding of mTERF to this site promotes termination of rDNA transcription. Despite the fact that mTERF binds DNA as a monomer, the presence in its sequence of three leucine-zipper motifs suggested the possibility of mTERF establishing intermolecular interactions with proteins of the same or different type. When a mitochondrial lysate from HeLa cells was submitted to gel filtration chromatography, mTERF was eluted in two peaks, as detected by immunoblotting. The first peak, which varied in proportion between 30 and 50%, appeared at the position expected from the molecular mass of the monomer (41 ± 2 kDa), and the gel filtration fractions that contained it exhibited DNA binding activity. Most interestingly, the material in this peak had a strong stimulating activity on in vitro transcription of the mitochondrial rDNA. The second peak eluted at a position corresponding to an estimated molecular mass of 111 ± 5 kDa. No mTERF DNA binding activity could be detected in the corresponding gel filtration fractions. Therefore, we propose that mTERF exists in mitochondria in two forms, an active monomer and an inactive large size complex. The estimated molecular weight of this complex and the fact that purified mTERF can be eluted from a gel filtration column as a complex of the same molecular weight strongly suggest that this inactive complex is a homotrimer of mTERF

Obtaining Of β-Lactoglobulin By Gel Filtration Of Cow Milk Whey

Milk whey proteins carry out a number of important biological functions and also they are precursors of many biologically active peptides (antihypertensive peptides, antagonists of opioid receptors, regulators of intestinal motility, immunomodulatory, anti-microbial and anti-cancer peptides, appetite regulators and so on.). An important stage in natural bioactive peptides obtaining from milk whey proteins is the isolation of homogeneous proteins-precursors. Considering the significant difference in the molecular masses of whey proteins, a promising method for their selection is gel filtration. The purpose of the research was the fractionation of bioactive peptides precursors from milk whey using gel filtration on Sephadex G-150. The whey was obtained from fresh skimmed milk after isoelectric precipitation of casein. Gel filtration was carried out on the columns from a liquid chromatography kit by the “Reanal” company. The fractional composition and the degree of homogeneity of milk whey proteins were determined by disc-electrophoresis in the plates of a polyacrylamide gel. A repeated gel filtration of fractions from the chromatographic peaks, separated into sections, was performed to increase the fractionation efficiency. While choosing a dextran gel for gel filtration of precursors of biologically active peptides from milk whey proteins, we have taken into account the range of their molecular weights (from 10000 to 150000 Da), the ability to form supramolecular structures (β-LG), as well as the previously obtained results of gel filtration. As a result, it was shown that repeated gel filtration of milk whey on Sephadex G-150 allows efficiently fractionate the proteins-precursors of bioactive peptides. The range of peptides and proteins molecular weights that can be fractionated on this Sephadex is from 5000 to 300 000 Da. The usage of repeated gel filtration on Sephadex G-150 with the chromatogram separation into sectors allows to effectively fractionate proteins-precursors of bioactive peptides from milk whey. In particular, homogeneous β-lactoglobulin (degree of homogeneity > 95 %) and partially purified α-lactalbumin, as well as a group of immunoglobulins and a proteose-peptone fraction were obtained

Studies on the cornin extracted from bovine liver. I. Purification of the cornin and its physico-chemical properties

A factor, cornin, inhibiting the growth of L cells cultured in monolayer was extracted from bovine liver with boiling water and was partially purified by gel filtration with Sephadex G-200. The factor was (1) precipitable with ethanol at the concentration between 70% and 90%, (2) impermeable through dializing memo brane, (3) eluted as the last peak at the gel filtration and (4) containing protein and RNA but no DNA.</p

Rubisco : easy purification and immunochemical determination

Rubisco (Ribulose-1.5-bisphosphate carboxylase/oxygenase) from spinach was purified to homogeneity in one step by gel filtration. This enzyme is suitable for the generation of a specific antibody in rabbits. The enzyme concentration in spinach leaves amounted to 40 % of the total soluble protein. The specific antibody shows cross reaction with crude extracts from leaves of other higher plants. The enzymes subunits could be separated by denaturing preparative SDS gel electrophoresis

Protein concentration of synovial fluid in chronic rheumatoid arthritis. Estimation of protein in the synovial fluid of chronic rheumatoid arthritis by gel filtration and paper electrophoresis

For the purpose to reveal the characteris6cs of the synovial fluid of the chronic rheumatoid arthritis the proteins of the synovial fluid and blood serum have been analysed by employing the methods of electrophoresis, gel filtration on Sephadex G-200 column and ultracentrifugation. Waaler-Rose test and latex fixation test have also been made on each protein fraction, and the following results were obtained. 1) The total protein level of synovial fluid, which is 3/5 of that of the serum, is slightly higher than that of control. 2) Fractionation of the synovial proteins by electrophoresis revealed nearly the same protein contents in each fraction in percentage as that of comparable fraction of the serum protein, with a slight increase in &#947;-globulin fraction. 3) The fractionation by Sephadex column G-200 give three peaks both in serum and synovial fluid, 19 S, 7Sand 4S. 4) 19S fraction of the synovial fluid, which is mainly of &#947;-globulin, showed a higher level than that of the synovial fluid from the controls. 5) Rheumatoid tests gave positive reaction in the 1st peak containing 19S &#947;-globulin from the synovial fluid and blood serum.</p

Copurification of actin and desmin from chicken smooth muscle and their copolymerization in vitro to intermediate filaments

Desmin is a 50,000-mol wt protein that is enriched along with 100-A filaments in chicken gizzard that has been extracted with 1 M KI. Although 1 M KI removes most of the actin from gizzard, a small fraction of this protein remains persistently insoluble, along with desmin. The solubility properties of this actin are the same as for desmin: they are both insoluble in high salt concentrations, but are solubilized at low pH or by agents that dissociate hydrophobic bonds. Desmin may be purified by repeated cycles of solubilization by 1 M acetic acid and subsequent precipitation by neutralization to pH 4. During this process, a constant nonstoichiometric ratio of actin to desmin is attained. Gel filtration on Ultrogel AcA34 in the presence of 0.5% Sarkosyl NL-97 reveals nonmonomeric fractions of actin and desmin that comigrate through the column. Gel filtration on Bio-Gel P300 in the presence of 1 M acetic acid reveals that the majority of desmin is monomeric under these conditions. A small fraction of desmin and all of the actin elute with the excluded volume. When the acetic acid is removed from actin-desmin solutions by dialysis, a gel forms that is composed of filaments with diameters of 120-140 A. These filaments react uniformly with both anti-actin and anti-desmin antiserum. These results suggest that desmin is the major subunit of the muscle 100-A filaments and that it may form nonstoichiometric complexes with actin

Association between cholesterol-phospholipid vesicles and cholesterol crystals in human gallbladder bile

Rapid aggregation of cholesterol-phospholipid vesicles in gallbladder bile seems to be the first event in the production of cholesterol crystals, a prerequisite for cholesterol gallstone formation. We examined the amount of these vesicles in 33 human gallbladder biles in relation to biliary lipid composition and to the presence of cholesterol crystals. Biliary microscopy detected cholesterol crystals in all 19 biles from patients with cholesterol gallstones but in none of 14 biles from patients with pigment stones. Gel chromatography was used to separate vesicles and micelles in the native bile with an eluting buffer containing 10 mM sodium cholate to prevent disruption of micellar lipids. Cholesterol, phospholipid and bile salt concentrations were measured in every fraction collected. Bile acid, phospholipid, cholesterol and total lipid concentrations were not significantly different in samples with and without cholesterol crystals. The cholesterol saturation index (1.4 ± 0.11 vs. 1.0 ± 0.08) was significantly (p < 0.01) higher in biles with crystals than without crystals. Gel filtration revealed a vesicular peak in addition to micellar fraction in 18 (23.1 ± 3.2% of total cholesterol) of the 19 biles with crystals but only in three (15.7 ± 2.4% of total cholesterol) of 14 biles without crystals. There was no relation between biliary lipid concentration or the cholesterol saturation index and the percentage of vesicular cholesterol in biles with or without crystals. The close association of vesicles and crystals in human gallbladder bile supports the contention that vesicles are important in the initial nucleation of cholesterol monohydrate crystals

The development of a purification procedure for Peptide:n-Glycosidase A from Prunus amygdalus : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry at Massey University

Peptide-N4-acetyl-β-glucosaminyl) asparagine amidases cleave the amide bond between N-linked glycans at N-acetylglucosamine and asparagine, liberating intact oligosaccharide chains from glycoproteins. Although PNGase A is commonly used by glycobiologists for removal of N-Iinked glycans from plant sources, much less is known about it than about PNGase F, an enzyme that is more commonly used for deglycosylating proteins. New studies on PNGase A have been initiated, with the aim of carrying out complete biochemical and structural studies in order to determine the substrate specificity, isoelectric point, primary, secondary and tertiary structures. Comparisons will then be made with PNGase F, whose three-dimensional structure is known. The first step in these studies is therefore to obtain some pure protein and amino acid sequence. Although purification protocols have been published previously, it was difficult to produce a homogeneous preparation following these methods and they have hence been modified. The methods used are described in Chapter 2 and the results of four preparations, using almond meal and almond emulsin as starling materials, are reported in Chapters 3-6. Although PNGase A had not been purified to homogeneity, an active band excised from a native gel and analysed by SDS-PAGE showed four major bands. Which band represents PNGase A remains to be determined