Pulsed ELDOR Determination of the Intramolecular Distance between the Metal Binding Sites in Dicupric Human Serum Transferrin and Lactoferrin

2007 ◽  
Vol 129 (16) ◽  
pp. 4868-4869 ◽  
Author(s):  
Christopher W. M. Kay ◽  
Hassane El Mkami ◽  
Richard Cammack ◽  
Robert W. Evans
Keyword(s):  
Human Serum ◽  
Metal Binding ◽  
Binding Sites ◽  
Serum Transferrin ◽  
Human Serum Transferrin ◽  
Metal Binding Sites ◽  
Intramolecular Distance

scholarly journals The distribution of iron between the metal-binding sites of transferrin human serum

1980 ◽  
Vol 185 (2) ◽  
pp. 483-488 ◽  
Author(s):  
J Williams ◽  
K Moreton
Keyword(s):  
Human Serum ◽  
Metal Binding ◽  
Binding Sites ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Iron Binding ◽  
Metal Binding Sites ◽  
Fresh Serum ◽  
Marked Preference ◽  
Terminal Site

The Makey & Seal [(1976) Biochim. Biophys. Acta 453, 250-256] method of polyacrylamide-gel electrophoresis in buffer containing 6 M-urea was used to determine the distribution of iron between the N-terminal and C-terminal iron-binding sites of transferrin in human serum. In fresh serum the two sites are unequally occupied; there is preferential occupation of the N-terminal site. On incubation of the serum at 37 degrees C the preference of iron for the N-terminal site becomes more marked. On storage of serum at −15 degrees C the iron distribution changes so that there is a marked preference for the C-terminal site. Dialysis of serum against buffer at pH 7.4 also causes iron to be bound much more strongly by the C-terminal than by the N-terminal site. The original preference for the N-terminal site can be resroted to the dialysed serum by addition of the diffusible fraction.

scholarly journals Periodate Modification of Human Serum Transferrin Fe(III)-binding Sites.

1995 ◽  
Vol 270 (21) ◽  
pp. 12404-12410 ◽  
Author(s):  
David C. Ross ◽  
Timothy J. Egan ◽  
Langley R. Purves
Keyword(s):  
Human Serum ◽  
Binding Sites ◽  
Serum Transferrin ◽  
Human Serum Transferrin

Effects of Mutations of Aspartic Acid 63 on the Metal-Binding Properties of the Recombinant N-Lobe of Human Serum Transferrin†

Biochemistry ◽  
1997 ◽  
Vol 36 (18) ◽  
pp. 5522-5528 ◽  
Author(s):  
Qing-Yu He ◽  
Anne B. Mason ◽  
Robert C. Woodworth ◽  
Beatrice M. Tam ◽  
Toby Wadsworth ◽  
...  
Keyword(s):  
Human Serum ◽  
Aspartic Acid ◽  
Metal Binding ◽  
Serum Transferrin ◽  
Binding Properties ◽  
Human Serum Transferrin

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.

Automation of a Quantitative Immunochemical Microanalysis of Human Serum Transferrin: A Model System

1970 ◽  
Vol 16 (7) ◽  
pp. 558-561 ◽  
Author(s):  
Irving Eckman ◽  
John B Robbins ◽  
C J A Van den Hamer ◽  
John Lentz ◽  
I Herbert Scheinberg
Keyword(s):  
Standard Deviation ◽  
Human Serum ◽  
Model System ◽  
Serum Transferrin ◽  
Human Serum Transferrin ◽  
True Value ◽  
Immunochemical Determination

Abstract The quantitative immunochemical determination of human serum transferrin was automated with a 100-µl sample. The estimated standard deviation from the true value was 7.9 mg/100 ml in 21 samples of serum, which had transferrin concentrations of 139-325 mg/100 ml.

DETERMINATION OF NUMBER OF γ-CARBOXYGLUTAMIC ACID (GLA) RESIDUES INVOLVED IN FORMING THE TWO HIGH AFFINITY METAL BINDING SITES IN PROTHROMBIN AND FACTOR X

1987 ◽  
Author(s):  
G L Brodsky ◽  
S P Bajaj
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Ion Binding ◽  
Factor X ◽  
Metal Binding Sites ◽  
High Affinity ◽  
Carboxyglutamic Acid ◽  
High Affinity Site ◽  
Ion Binding Sites

Prothrombin and factor X possess two high affinity and several low affinity lanthanide ion binding sites. In both proteins, the association constant of the high affinity sites is at least 50-fold greater than that of the low affinity sites. Moreover, metal bound to these high affinity sites is extremely difficult to displace. It has been proposed that one of the two high affinity sites in factor X involves Gla residues while the other involves β-hydroxyaspartic acid and no Gla residues. It is also known that ^H can be specifically incorporated into Gla residues at an acidic pH. We have determined that under nondenaturing conditions when Gla (synthetic or in proteins) is complexed to metal at pH 5.5, this specific 3H incorporation is blocked. Furthermore, we have found that β-hydroxyaspartic acid does not incorporate in the presence or absence of metal. When we incubated prothrombin or factor X (41 μM) with 3H2O in the presence of Tb3+ or Gd3+ (82 μM), we blocked 5.6 Gla residues per prothrombin and 5.5 Gla residues per factor X from 3H incorporation. Under these conditions, we calculated that >95% of the high affinity sites are occupied by metal. Thus, in prothrombin, an average of 2.8 Gla residues are involved in forming each high affinity site. If the Gla residues in factor X participate in forming only one of the two high affinity sites, then all 5.5 Gla residues blocked from incorporation must be involved in forming that site. However, this seems highly unlikely. We conclude that, as in prothrombin, both high affinity sites in factor X involve Gla residues (average 2.75/site). However, our data does not exclude the possibility of existence of a heterologous site containing both β-hydroxyaspartic acid and Gla residues.

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