scholarly journals Mobilization of the iron centre in IscA for the iron–sulphur cluster assembly in IscU

2005 ◽  
Vol 389 (3) ◽  
pp. 797-802 ◽  
Author(s):  
Baojin Ding ◽  
Edward S. Smith ◽  
Huangen Ding
Keyword(s):  
Escherichia Coli ◽  
Reduced Glutathione ◽  
Binding Protein ◽  
Iron Binding ◽  
Cluster Assembly ◽  
Uv Visible ◽  
Iron Binding Protein ◽  
Epr Measurements

The biogenesis of iron–sulphur clusters requires the co-ordinated delivery of both iron and sulphur. It is now clear that sulphur in iron–sulphur clusters is derived from L-cysteine by cysteine desulphurases. However, the iron donor for the iron–sulphur cluster assembly still remains elusive. Our previous studies indicated that Escherichia coli IscA, a member of the iron–sulphur cluster assembly machinery, is an iron-binding protein that can provide iron for the iron–sulphur cluster assembly in a proposed scaffold IscU. To determine how the iron centre in IscA is transferred for the iron–sulphur cluster assembly in IscU, we explore the mobility of the iron centre in IscA. The UV–visible and EPR measurements show that L-cysteine, but not IscU, is able to mobilize the iron centre in IscA and make the iron available for the iron–sulphur cluster assembly in IscU. Other related biological thiols such as N-acetyl-L-cysteine or reduced glutathione have no effect on the iron centre of IscA, suggesting that L-cysteine is unique in mobilizing the iron centre of IscA. Nevertheless, L-cysteine alone is not sufficient to transfer the iron from IscA to IscU. Both L-cysteine and cysteine desulphurase (IscS) are required for the IscA-mediated assembly of iron–sulphur clusters in IscU. The results suggest that L-cysteine may have two distinct functions in the biogenesis of iron–sulphur clusters: to mobilize the iron centre in IscA and to provide sulphur via cysteine desulphurase (IscS) for the iron–sulphur cluster assembly in IscU.

scholarly journals Bacteriostasis ofEscherichia coliby milk. III. The activity and stability of early, transitional and mature human milk collected locally

1979 ◽  
Vol 83 (2) ◽  
pp. 243-254 ◽  
Author(s):  
Pauline Honour ◽  
Jean M. Dolby
Keyword(s):  
Escherichia Coli ◽  
Resistant Strain ◽  
Binding Protein ◽  
Post Partum ◽  
Bacteriostatic Activity ◽  
Iron Binding ◽  
Early Lactation ◽  
E Coli ◽  
Progressive Loss ◽  
Iron Binding Protein

summaryMilk from 150 local mothers has been assayed for bacteriostatic activity for milk-sensitive and milk-resistant indicator strains ofEscherichia coli. Activity is greatest in colostrum which is active directly against all strains ofE. coli. One week after delivery of the baby, milk is active against the milk-sensitive strain and becomes active against the milk-resistant strain in the presence of physiological amounts of bicarbonate and iron-binding protein. This activity decreases within 2–4 days on keeping milk unheated at 4 °C but is preserved for at least 4 months and often up to 2 years in milk heated to 56 °C then stored at 4 °C or in milk frozen, unheated, at −28 °C provided it is not repeatedly thawed and frozen. Later lactation milks are usually indistinguishable in activity from 1-week post-partum milk but may be less stable on storage particularly if frozen. Lyophilizationin vacuopreserves activity of early-lactation milk for at least 6 months.Heating milk to above 65 °C causes a progressive loss of activity which can be partially restored by adding bicarbonate and iron-binding protein. Iron abolishes the activity of milk and reduces that of colostrum.

scholarly journals Characterization of iron binding in IscA, an ancient iron-sulphur cluster assembly protein

2004 ◽  
Vol 379 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Huangen DING ◽  
Robert J. CLARK
Keyword(s):  
Association Constant ◽  
Binding Protein ◽  
Iron Binding ◽  
Cluster Assembly ◽  
Intracellular Iron ◽  
Ancient Iron ◽  
Iron Binding Protein ◽  
Redox Centre

Iron–sulphur clusters are one of the most common types of redox centre in biology. At least six proteins (IscS, IscU, IscA, HscB, HscA and ferredoxin) have been identified as being essential for the biogenesis of iron–sulphur proteins in bacteria. It has been shown that IscS is a cysteine desulphurase that provides sulphur for iron–sulphur clusters, and that IscU is a scaffold for the IscS-mediated assembly of iron–sulphur clusters. The iron donor for iron–sulphur clusters, however, remains elusive. Here we show that IscA is an iron binding protein with an apparent iron association constant of 3.0×1019 M−1, and that iron-loaded IscA can provide iron for the assembly of transient iron–sulphur clusters in IscU in the presence of IscS and l-cysteine in vitro. The results suggest that IscA is capable of recruiting intracellular iron and delivering iron for iron–sulphur clusters in proteins.

scholarly journals Lactoferrin-an iron binding protein in synovial fluid

1973 ◽  
Vol 16 (2) ◽  
pp. 186-190 ◽  
Author(s):  
Robert M Bennett ◽  
A C Eddie-Quartey ◽  
P J L Holt
Keyword(s):  
Synovial Fluid ◽  
Binding Protein ◽  
Iron Binding ◽  
Iron Binding Protein

scholarly journals Iron-Binding Protein of Swine Serum.

1947 ◽  
Vol 1 ◽  
pp. 770-776 ◽  
Author(s):  
C.-B Laurell ◽  
B. Ingelman
Keyword(s):  
Binding Protein ◽  
Iron Binding ◽  
Iron Binding Protein ◽  
Swine Serum

scholarly journals IRON METABOLISM

Blood ◽  
1950 ◽  
Vol 5 (11) ◽  
pp. 983-1008 ◽  
Author(s):  
CLEMENT A. FINCH ◽  
MARK HEGSTED ◽  
THOMAS D. KINNEY ◽  
E. D. THOMAS ◽  
CHARLES E. RATH ◽  
...  
Keyword(s):  
Iron Metabolism ◽  
Serum Iron ◽  
Iron Absorption ◽  
Binding Protein ◽  
The Body ◽  
Iron Binding ◽  
Body Iron ◽  
Iron Administration ◽  
Parenteral Iron ◽  
Iron Binding Protein

Abstract On the basis of experimental and clinical observations and a review of the literature, a concept of the behavior of storage iron in relation to body iron metabolism has been formulated. Storage iron is defined as tissue iron which is available for hemoglobin synthesis when the need arises. This iron is stored intracellularly in protein complex as ferritin and hemosiderin. It would appear that wherever the cell is functionally intact, such iron is available for general body needs. Iron is transported by a globulin of the serum to and from the various tissues of the body to satisfy their metabolism. Surplus iron carried by this iron-binding protein is deposited chiefly in the liver. Storage iron may be increased in two ways. The first mechanism results from the inability of the body to excrete significant amounts of iron. Because of this, any decrease in circulating red cell iron (any anemia other than blood loss or iron deficiency anemia) is accompanied by a shift of iron to the tissue compartment. The total amount of body iron remains constant and is merely redistributed. This is to be contrasted with the absolute increase in body iron and enlarged iron stores which follow excessive iron absorption or parenteral iron administration. Enlarged iron stores in either instance may be evaluated by examination of sternal marrow or determination of the serum iron and saturation of the iron binding protein In states of iron excess, differences in initial distribution are observed, depending on the route of administration and type of iron compound employed. Iron absorbed from the gastro-intestinal tract and soluble iron salts injected in small amounts are transported by the iron-binding protein of the serum and stored predominantly in the liver. Colloidal iron given intravenously is taken up by the reticulo-endothelial tissue. Erythrocytes appear to localize in greatest concentration in the spleen, while greater amounts of hemoglobin iron are found in the renal parenchyma. These latter differences in distribution reflect the capacity of various body tissues to assimilate different iron compounds, which while present in the plasma are not carried by the iron-binding protein. Over a period of time an internal redistribution of iron from these various sites occurs through the serum iron compartment. The liver becomes progressively loaded with iron. When the capacity of the liver to store iron is exceeded, the serum iron increases and secondary tissue receptors begin to fill with iron. That iron in large amounts is toxic to tissues is suggested by the occurrence of fibrosis in the organs most heavily laden with iron. This sequence of events, whether following excessive iron absorption or parenteral iron administration is believed to be responsible for the clinical and pathologic picture of hemochromatosis.

scholarly journals The superoxide-dependent transfer of iron from ferritin to transferrin and lactoferrin

1988 ◽  
Vol 256 (3) ◽  
pp. 923-928 ◽  
Author(s):  
H P Monteiro ◽  
C C Winterbourn
Keyword(s):  
Lipid Peroxidation ◽  
Free Radicals ◽  
Xanthine Oxidase ◽  
Binding Protein ◽  
Gel Filtration ◽  
Iron Binding ◽  
Oxidase System ◽  
Oxidative Reactions ◽  
Phospholipid Liposomes ◽  
Iron Binding Protein

By the use of gel filtration and [59Fe]ferritin, apotransferrin and apolactoferrin were shown to take up iron released from ferritin by superoxide generated by hypoxanthine and xanthine oxidase. Apotransferrin also inhibited uptake of released iron by ferrozine. Ferritin and the xanthine oxidase system induced lipid peroxidation in phospholipid liposomes. This peroxidation was inhibited by apotransferrin or apolactoferrin. Thus, although superoxide and other free radicals can release iron from ferritin, either iron-binding protein, if present, should take up this iron and prevent its catalysing subsequent oxidative reactions.

Sign in / Sign up

Export Citation Format

Share Document