scholarly journals The electrophoresis of transferrins in urea/polyacrylamide gels

1980 ◽  
Vol 189 (3) ◽  
pp. 541-546 ◽  
Author(s):  
R W Evans ◽  
J Williams
Keyword(s):  
Human Serum ◽  
Binding Capacity ◽  
Serum Transferrin ◽  
Iron Binding ◽  
Polyacrylamide Gels ◽  
Human Serum Transferrin ◽  
Free Protein ◽  
Iron Binding Capacity ◽  
Terminal Domains

The denaturation of transferrin by urea has been studied by (a) electrophoresis in polyacrylamide gels incorporating a urea gradient, (b) measurements of the loss of iron-binding capacity and (c) u.v. difference spectrometry. In human serum transferrin and hen ovotransferrin the N-terminal and C-terminal domains of the iron-free protein were found to denature at different urea concentrations.

The glycation site specificity of human serum transferrin is a determinant for transferrin's functional impairment under elevated glycaemic conditions

2014 ◽  
Vol 461 (1) ◽  
pp. 33-42 ◽  
Author(s):  
André M. N. Silva ◽  
Paulo R. H. Sousa ◽  
João T. S. Coimbra ◽  
Natércia F. Brás ◽  
Rui Vitorino ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Amino Acid ◽  
Human Serum ◽  
Serum Transferrin ◽  
Site Specificity ◽  
Iron Binding ◽  
Amino Acid Residues ◽  
Human Serum Transferrin ◽  
Structural Alterations ◽  
Iron Binding Protein

Human serum transferrin is susceptible to modification under elevated glycaemic conditions, such as those encountered in diabetes mellitus. The study of transferrin glycation shows that key amino acid residues undergo glycation, inducing structural alterations that compromise its function as an iron-binding protein.

scholarly journals Fully automated measurement of total iron-binding capacity in serum

1997 ◽  
Vol 43 (12) ◽  
pp. 2413-2417 ◽  
Author(s):  
Hachiro Yamanishi ◽  
Shigeki Kimura ◽  
Shigeru Iyama ◽  
Yoshihisa Yamaguchi ◽  
Takehiko Yanagihara
Keyword(s):  
Binding Capacity ◽  
Colorimetric Method ◽  
Total Iron ◽  
Second Step ◽  
Serum Transferrin ◽  
Acidic Ph ◽  
Iron Binding ◽  
Total Iron Binding Capacity ◽  
Automated Measurement ◽  
Iron Binding Capacity

Abstract We established a method for fully automated measurement of total iron-binding capacity (TIBC) in serum without separation of the unbound excess iron after saturating serum transferrin. After saturation of serum transferrin with an excess amount of iron (first step), the unbound iron was eliminated by formation of a complex with ferrozine, which was used as a chromogenic reagent (second step). For the TIBC assay, iron dissociated from transferrin by shifting the pH to acidic was reacted with ferrozine, and the increase in the absorbance at 570 nm was measured (third step). Because the iron used as a calibrator, which was added to saturate transferrin, reacted completely with ferrozine in the second step (elimination of unbound iron), the change in the absorbance to generate a calibration factor could not be monitored in the third step. To solve this problem, we used N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid (HEDTA) to complex with the iron added to saturate transferrin in the second step. This made it possible to form an iron–ferrozine complex at acidic pH because iron was dissociated from HEDTA at acidic pH. The within-run CVs of this method were 0.66–2.43% at 17.7–77.0 μmol/L, and the day-to-day CVs were 1.06–1.57% at 29.9–60.4 μmol/L (n = 10). The correlation between the values obtained with this method (y) and those from the direct TIBC assay, which involved removal of unbound iron by ion-exchange resin (x), was: y = 0.963x + 0.29 μmol/L (r = 0.973, Sy|x = 2.83, n = 59), and with the TIBC values calculated from the serum iron concentrations and the unbound iron-binding capacities measured by a direct colorimetric method (x) was: y = 1.01x − 1.06 μmol/L (r = 0.994, Sy|x = 1.66, n = 51).

scholarly journals Studies of the binding of different iron donors to human serum transferrin and isolation of iron-binding fragments from the N- and C-terminal regions of the protein

1978 ◽  
Vol 173 (2) ◽  
pp. 543-552 ◽  
Author(s):  
R W Evans ◽  
J Williams
Keyword(s):  
Amino Acid ◽  
Human Serum ◽  
Terminal Region ◽  
The Other ◽  
Serum Transferrin ◽  
Iron Binding ◽  
Proteolytic Digestion ◽  
Human Serum Transferrin ◽  
Partially Saturated ◽  
Peptide Maps

1. Trypsin digestion of human serum transferrin partially saturated with iron(III)-nitrilotriacetate at pH 5.5 or pH 8.5 produces a carbohydrate-containing iron-binding fragment of mol.wt. 43000. 2. When iron(III) citrate, FeCl3, iron (III) ascorabate and (NH4)2SO4,FeSO4 are used as iron donors to saturate the protein partially, at pH8.5, proteolytic digestion yields a fragment of mol.wt. 36000 that lacks carbohydrate. 3. The two fragments differ in their antigenic structures, amino acid compositions and peptide ‘maps’. 4. The fragment with mol.wt. 36000 was assigned to the N-terminal region of the protein and the other to the C-terminal region. 5. The distribution of iron in human serum transferrin partially saturated with various iron donors was examined by electrophoresis in urea/polyacrylamide gels and the two possible monoferric forms were unequivocally identified. 6. The site designated A on human serum transferrin [Harris (1977) Biochemistry 16, 560–564] was assigned to the C-terminal region of the protein and the B site to the N-terminal region. 7. The distribution of iron on transferrin in human plasma was determined.

A Density Functional Theory Study of the Iron-Binding Site of Human Serum Transferrin

2004 ◽  
Vol 57 (12) ◽  
pp. 1219 ◽  
Author(s):  
David Rinaldo ◽  
Martin J. Field
Keyword(s):  
Human Serum ◽  
Binding Site ◽  
Conformational Changes ◽  
Metal Binding ◽  
Density Functional ◽  
Release Mechanism ◽  
Serum Transferrin ◽  
Iron Binding ◽  
Iron Release ◽  
Human Serum Transferrin

Human serum transferrin binds ferric ions with high affinity in the blood stream and releases them into cells by a process involving receptor-mediated endocytosis and a decrease in pH. The iron-release mechanism is unclear but protonation events and conformational changes are known to be important. In this study, we investigate properties of the iron-binding site theoretically. Our results suggest that an equatorial histidine could be in its histidinate form when bound to iron at neutral and high pH and that protonation of an axial tyrosine is a key event in iron release. Support for this mechanism from other metal-binding enzymes is also presented.

scholarly journals Immunoturbidimetric determination of serum transferrin on a Kone Progress autoanalyser

1989 ◽  
Vol 11 (1) ◽  
pp. 40-41 ◽  
Author(s):  
Luc Cynober ◽  
Jacques Le Boucher ◽  
Jacqueline Giboudeau
Keyword(s):  
Binding Capacity ◽  
Clinical Chemistry ◽  
Total Iron ◽  
Radial Immunodiffusion ◽  
Serum Transferrin ◽  
Iron Binding ◽  
Total Iron Binding Capacity ◽  
French Society ◽  
Iron Binding Capacity

The Kone Progress, a multiparametric discrete analyser, was used to determine serum transferrin with a kit supplied by Kone. Assays recommended by the French Society of Clinical Chemistry were performed in order to assess the suitability of the test. Repeatability was assessed using serum pools with low (L), medium (M) and high (H) concentrations of transferrin. The coeffcients of variation (CV) were 5.4, 3.2 and 2.0% respectively for 30 determinations (within-batch). Reproducibility on 15 consecutive days (between-batch) was also satisfactory (CV for L = 7.3%, M = 6.3% and H = 3.8%). There was no serum-to-serum contamination. Results correlated closely with those obtained using radial immunodiffusion (RID) (r = 0.942) and total iron-binding capacity (r = 0.954)for 90 determinations.Transferrin measurement by immunoturbidimetry on the Kone Progress emerges as a well-suited, rapid and inexpensive alternative to other time-consuming (RID) and sophisticated (laser immunonephelemeter) techniques.

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