scholarly journals Biosynthesis of serum albumin in rat liver. Evidence for the existence of ‘proalbumin’

1973 ◽  
Vol 134 (4) ◽  
pp. 1083-1091 ◽  
Author(s):  
J. D. Judah ◽  
Margaret Gamble ◽  
J. H. Steadman
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Peptide Mapping ◽  
Protein S ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Small Peptide ◽  
Previous Suggestion ◽  
Tryptic Hydrolysis

1. A protein(s) of rat liver (precipitated from soluble extracts of the microsomal fraction by anti-albumin) yields albumin after limited hydrolysis by trypsin. 2. Evidence that the product of limited tryptic hydrolysis is albumin, is based upon ion-exchange chromatography, electrofocusing and peptide `mapping'. 3. The albumin `precursor' is recognized by anti-albumin and is apparently not distinguished from albumin by anti-albumin. 4. A small peptide is liberated from the presumptive albumin precursor during limited tryptic hydrolysis. This peptide is labelled by arginine, but not by leucine, lysine or methionine. 5. These results support our previous suggestion based on kinetic evidence that the albumin-like protein(s), in the anti-albumin precipitate from rat liver, is an albumin precursor.

scholarly journals Regulation of the pentose phosphate cycle Cofactor that controls the inhibition of glucose-6-phosphate dehydrogenase by NADPH in rat liver

1986 ◽  
Vol 239 (3) ◽  
pp. 553-558 ◽  
Author(s):  
M Nogueira ◽  
G Garcia ◽  
C Mejuto ◽  
M Freire
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
Pentose Phosphate Pathway ◽  
Reductase Activity ◽  
Gel Filtration ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Pentose Phosphate ◽  
Glutathione Reductase Activity ◽  
Glucose 6 Phosphate Dehydrogenase

A cofactor of Mr 10(4), characterized as a polypeptide, was found to co-operate with GSSG to prevent the inhibition of glucose-6-phosphate dehydrogenase by NADPH, in order to ensure the operation of the oxidative phase of the pentose phosphate pathway, in rat liver [Eggleston & Krebs (1974) Biochem. J. 138, 425-435; Rodriguez-Segade, Carrion & Freire (1979) Biochem. Biophys. Res. Commun. 89, 148-154]. This cofactor has now been partially purified by ion-exchange chromatography and molecular gel filtration, and characterized as a protein of Mr 10(5). The lighter cofactor reported previously was apparently the result of proteolytic activity generated during the tissue homogenization. The heavier cofactor was unstable, and its amount increased in livers of rats fed on carbohydrate-rich diet. Since the purified cofactor contained no glutathione reductase activity, the involvement of this enzyme in the deinhibitory mechanism of glucose-6-phosphate dehydrogenase by NADPH should be ruled out.

scholarly journals Biosynthesis of serum albumin in rat liver. Isolation and probable structure of ‘proalbumin’ from rat liver

1975 ◽  
Vol 146 (2) ◽  
pp. 389-393 ◽  
Author(s):  
P S Quinn ◽  
M Gamble ◽  
J D Judah
Keyword(s):  
Ion Exchange ◽  
Serum Albumin ◽  
Rat Liver ◽  
Isoelectric Focusing ◽  
Exchange Chromatography ◽  
Rat Serum ◽  
Ph Gradients ◽  
Gel Isoelectric Focusing ◽  
Tryptic Hydrolysis ◽  
Rat Serum Albumin

1. Two methods are described for the preparation of ‘proalbumin’ in good yields from rat liver. 2. One of the methods does not depend on the use of specific antisera. 3. The product from both methods is identical as judged by electrophoresis on polyacrylamide gel, isoelectric focusing on pH gradients, ion-exchange chromatography and quantitative immunoelectrophoresis. The protein also appears to be radiochemically pure by these criteria. 4. The protein is free from serum albumin as judged by isoelectric focusing and co-chromatography on ion-exchange columns. It is judged to be free from other proteins by these same criteria and by specific precipitation with antibody. 5. It is converted into serum albumin by limited tryptic hydrolysis. The albumin so produced has the same N-terminal (glutamic acid) and C-terminal (alanine) amino acids as reported for rat serum albumin. 6. A hexapeptide is liberated from the N-terminal end of ‘proalbumin’ simultaneously. It contains three arginine, one phenylalanine, one valine and one glycine residues.

scholarly journals Rat liver contains a potent endogenous inhibitor of inositol 1,3,4,5-tetrakisphosphate 3-phosphatase

1990 ◽  
Vol 267 (3) ◽  
pp. 831-834 ◽  
Author(s):  
M E Hodgson ◽  
S B Shears
Keyword(s):  
Ion Exchange ◽  
Phosphatase Activity ◽  
Rat Liver ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Endogenous Inhibitor ◽  
Stable Factor ◽  
Heat Stable

When Ins(1,3,4,5)P4 was incubated with a rat liver 100,000 g supernatant, about 93% of the substrate was metabolized by a 5-phosphatase, and only 7% by a 3-phosphatase. Ion-exchange chromatography of the supernatant specifically increased its 3-phosphatase activity 72 +/- 3-fold. This activated enzyme was inhibited by a heat-stable factor present in both the soluble and particulate portions of the cell.

IODOPEPTIDES FROM HUMAN THYROGLOBULIN

1977 ◽  
Vol 85 (4) ◽  
pp. 769-780 ◽  
Author(s):  
Lubomir J. Valenta ◽  
A. Donny Strosberg ◽  
Vera Valenta ◽  
Jean-Claude Jaton
Keyword(s):  
Ion Exchange ◽  
Peptide Mapping ◽  
Thyroid Tissue ◽  
Iodine Content ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Small Peptides ◽  
Thyroid Glands ◽  
High Voltage Electrophoresis

ABSTRACT Human thyroglobulin labelled in vivo by 125I was purified from eight different thyroid glands including normal thyroid tissue, thyrotoxic goitre and euthyroid multinodular goitre. The purified protein was cleaved with cyanogen bromide (CNBr) and the resulting peptides were separated by column chromatography and ion exchange chromatography. Reproducible elution profiles of both protein and iodine were obtained. However, the distribution of iodine depended on the iodine content of the intact thyroglobulin. Small CNBr peptides seemed to be preferentially iodinated, but with a limited capacity. With higher degrees of iodination, larger peptides became richer in iodine. This suggests sequential iodination of the thyroglobulin molecule. The mixture of small peptides was digested by trypsin. Two iodopeptides were identified in this material by peptide mapping and they had identical migration in thyroglobulins of different origin. One of them was purified by ion exchange chromatography and high voltage electrophoresis. Analogous amino acid composition was obtained for the iodopeptide purified from two different thyroglobulins. The data indicates that thyroglobulin iodination occurs in specific portions of the polypeptide chain and probably in a sequential manner.

scholarly journals Evidence for a protein regulator from rat liver which activates acetyl-CoA carboxylase

1993 ◽  
Vol 292 (1) ◽  
pp. 75-84 ◽  
Author(s):  
K A Quayle ◽  
R M Denton ◽  
R W Brownsey
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
High Speed ◽  
Deae Cellulose ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity

1. A regulator of acetyl-CoA carboxylase has been identified in high-speed supernatant fractions from rat liver. The regulator was found to activate highly purified acetyl-CoA carboxylase 2-3-fold at physiological citrate concentrations (0.1-0.5 mM). The effects of the regulator on acetyl-CoA carboxylase activity were dose-dependent, and half-maximal activation occurred in 7-8 min at 30 degrees C. 2. The acetyl-CoA carboxylase regulator was non-dialysable and was inactivated by heating or by exposure to carboxypeptidase. The regulator was enriched from rat liver cytosol by first removing the endogenous acetyl-CoA carboxylase and then using a combination of purification steps, including (NH4)2SO4 precipitation, ion-exchange chromatography and size-exclusion chromatography. The regulator activity appeared to be a protein with a molecular mass of approx. 75 kDa, which could be eluted from mono-Q with approx. 0.35 M KCl as a single peak of activity. 3. Studies of the effects of the regulator on phosphorylation or subunit size of acetyl-CoA carboxylase indicated that the changes in enzyme activity are most unlikely to be explained by dephosphorylation or by proteolytic cleavage. 4. The regulator co-migrates with acetyl-CoA carboxylase through several purification steps, including ion-exchange chromatography and precipitation with (NH4)2SO4; however, the proteins may be separated by Sepharose-avidin chromatography, and the association between the proteins is also disrupted by addition of avidin in solution. Furthermore, the binding of the regulator itself to DEAE-cellulose is altered by the presence of acetyl-CoA carboxylase. Taken together, these observations suggest that the effects of the regulator on acetyl-CoA carboxylase may be explained by direct protein-protein interaction in vitro.

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