Amount Of Nonheme Iron Research Articles

A randomized placebo-controlled clinical trial of oral green tea epigallocatechin 3-gallate on erythropoiesis and oxidative stress in transfusion-dependent β-thalassemia patients.

β-Thalassemia patients suffer from ineffective erythropoiesis and increased red blood cell (RBC) hemolysis. Blood transfusion, erythropoietic enhancement, and antioxidant supplementation can ameliorate chronic anemia. Green tea extract (GTE) is comprised of catechin derivatives, of which epigallocatechin-3-gallate (EGCG) is the most abundant, presenting free-radical scavenging, iron-chelating, and erythropoiesis-protective effects. The present study aimed to evaluate the effects of GTE tablets on the primary outcome of erythropoiesis and oxidative stress parameters in transfusion-dependent β-thalassemia (TDT) patients. Twenty-seven TDT patients were randomly divided into placebo and GTE tablet (50 and 100mg EGCG equivalent) groups and assigned to consume the product once daily for 60days. Blood was collected for analysis of hematological, biochemical, and oxidative stress parameters. Accordingly, consumption of GTE tablets improved blood hemoglobin levels when compared with the placebo; however, there were more responders to the GTE tablets. Interestingly, amounts of nonheme iron in RBC membranes tended to decrease in both GTE tablet groups when compared with the placebo. Importantly, consumption of GTE tablets lowered plasma levels of erythroferrone (p < 0.05) and reduced bilirubin non-significantly and dose-independently. Thus, GTE tablets could improve RBC hemolysis and modulate erythropoiesis regulators in transfusion-dependent thalassemia patients.

Effect of reactive oxygen species on the erythrocyte calcium-pump function in protein-energy malnutrition.

The presence of detectable amounts of non-heme iron in erythrocyte ghost membranes have been postulated to lead to the initiation of membrane lipid peroxidation and the attendant perturbation of membrane functions. We have investigated the presence of non-heme iron and endogenous products of lipid peroxidation in erythrocyte membranes of normal and kwashiorkor (KWA) subjects and assessed the susceptibility of the membranes to exogenously generated reactive oxygen species. The modulation of the basal and calmodulin-stimulated calcium-pumping activity of these membranes by reactive oxygen species was also assessed. The results show the presence of significant amounts of non-heme iron and endogenous free radical reaction products in the red cell membranes of KWA subjects compared with that of normal children. Estimation of the extent of lipid peroxidation in the presence of exogenously generated reactive oxygen species further revealed that erythrocyte ghost membranes of KWA subjects are more susceptible to oxidative stress than those of normal individuals. Although both the basal and calmodulin-stimulated activities of the membrane-bound Ca(2+)-pump enzyme in normal and KWA subjects were inhibited by oxygen-free radicals, the erythrocyte enzyme in KWA subjects showed higher susceptibility to inhibition by oxygen free radicals than that of normal individuals. We propose that the reduced erythrocyte calcium-pump function in KWA is not unconnected with excessive generation of reactive oxygen species.

Purification and properties of the intact P-700 and F x-containing Photosystem I core protein

The intact Photosystem I core protein, containing the psaA and psaB polypeptides, and electron transfer components P-700 through FX, was isolated from cyanobacterial and higher plant Photosystem I complexes with chaotropic agents followed by sucrose density ultracentrifugation. The concentrations of NaClO4, NaSCN, NaI, NaBr or urea required for the functional removal of the 8.9 kDa, FA/FB polypeptide was shown to be inversely related to the strength of the chaotrope. The Photosystem I core protein, which was purified to homogeniety, contains 4 mol of acid-labile sulfide and has the following properties: (i) the FX-containing core consists of the 82 and 83 kDa reaction center polypeptides but is totally devoid of the low-molecular-mass polypeptides; (ii) methyl viologen and other bipyridilium dyes have the ability to accept electrons directly from FX; (iii) the difference spectrum of FX from 400 to 900 nm is characteristic of an iron-sulfur cluster; (iv) the midpoint potential of FX, determined optically at room temperature, is 60 mV more positive than in the control; (v) there is indication by ESR spectroscopy of low-temperature heterogeneity within FX; and (vi) the heterogeneity is seen by optical spectroscopy as inefficiency in low-temperature electron flow to FX. The constraints imposed by the amount of non-heme iron and labile sulfide in the Photosystem I core protein, the cysteine content of the psaA and psaB polypeptides, and the stoichiometry of high-molecular-mass polypeptides, cause us to re-examine the possibility that FX is a [4Fe-4S] rather than a [2Fe-2S] cluster ligated by homologous cysteine residues on the psaA and psaB heterodimer.

Effect of decreased ferrochelatase activity on iron and porphyrin content in mitochondrai of mice with porphyria induced by griseofulvin

The content of iron and protoporphyrin in liver mitochondria from mice with porphyria induced by griseofulvin was measured. The amount of porphyrin was 0.0076 ± 0.0043, 4.11 ± 0.58 and 22.2 ± 6.8 nmol/mg protein ( n = 5) in mitochondria from control animals and animals treated with griseofulvin for 3 days and 4–5 weeks, respectively. The energy coupling of the mitochondia was greatly diminished after 4–5 weeks of treatment, and the ferrochelatase activity was inhibited 80–90%, compared to that of control animals. Mitochondrial preparations isolated by differential centrifugation were contaminated with iron-containing lysosomes which could be removed by Percoll density-gradient centrifugation. In purified mitochondrial preparations no change in the amount of non-heme iron was found after griseofulvin feeding, representing 3.36±0.15, 3.97±0.40 and 3.59±0.23 nmol/mg protein for control animals, 3 days- and 4–5 weeks-treated animals, respectively ( n = 4). A mitochondrial iron pool previously identified in rat liver mitochondria and shown to be available for heme synthesis in vitro (Tangerås, A. (1985)) Biochim. Biophys. Acta 843 199–207) was also present in mitochondria from mice. The magnitude of this iron pool, as well as its availability for heme synthesis, was not changed after treatment of the animals with griseofulvin. The fact that porphyrin, but not iron, accumulated in the mitochondria when ferrochelatase was inhibited is discussed with regard to our understanding of the process of heme synthesis and its regulation.

Iron content and degree of lipid peroxidation in liver mitochondria isolated from iron-loaded rats

1.The content of non-heme iron and the degree of lipid peroxidation were measured in liver mitochondria isolated from rats injected with either Jectofer (an iron-sorbitol-citric acid complex) or iron-nitrilotriacetate. 2. The sedimentation profiles of the mitochondria from controls and iron-treated rats as revealed by analytical differential centrifugation, indicated single population of mitochondria with s 4,B values of 13200± 560 S and 14200±590 S for controls and iron-loaded animals, respectively. In contrast, the sedimentation profiles of the acid phosphatase activity and the non-heme iron revealed marked polydispersities with at least three populations of particles for both controls and iron-loaded animals. 3. The mitochondria and iron-rich lysosomes were separated by density-gradient centrifugation in an isotonic medium of Percoll and sucrose. With this technique, the amount of non-heme iron in a mitochondrial fraction by differential centrifugation decreased from 69±28 nmol/mg protein to 5.6±1.1 nmol/mg protein and from 19.3±5.6 nmol/mg protein to 3.3±0.6 nmol/mg protein for Jectofer and iron-nitrilotriacetate injected rats, respectively. For control rats the amount of mitochondrial non-heme iron was about 2.7 nmol/mg protein both before and following density gradient centrifugation. The extra amount of non-heme iron still present in the purified mitochondrial fraction from iron-loaded rats, as compared to controls, was further characterized by the reactivity towards bathophenanthroline sulfonate. The results suggest that the extra iron was due to a small amount of either ferritin or hemosiderin still contaminaning the mitochondrial fraction. The amount of mitochondrial heme iron was the same in iron-loaded rats and controls. 4. The degree of lipid peroxidation in the mitochondria was estimated from the amount of malondialdehyde. The thiobarbituric acid method used for the quantitation of malondialdehyde was modified so that it was insensitive to variable amounts of iron present in the samples. No difference in the degree of lipid peroxidation was observed between the mitochondria from iron-loaded rats and controls. 5. In contrast to recent proposals (Hanstein, E.G. et al. (1981) Biochim. Biophys. Acta 678, 293–299), the present study showed that the amounts of non-heme iron and the degrees of lipid peroxidation are the same in mitochondria isolated from iron-loaded and control animals.

Estimation of available dietary iron

Dietary iron requirements are dependent on the amount and availability of food iron ingested. On the basis of recent studies of food iron absorption employing extrinsic tag techniques, the availability of heme iron has been defined and estimates of the availability of nonheme iron based on the amounts of enhancing substances appear possible. A model has been developed whereby the availability of iron in a given meal may be estimated. Calculations are made on a meal basis of 1) the amount of heme iron and its availability, and 2) the amount of nonheme iron and its availability as influenced by the meal's content of enhancing factors. Examples of these calculations are provided

Partial Purification of NADH-Cytochrome &lt;italic&gt;b&lt;/italic&gt;&lt;sub&gt;5&lt;/sub&gt; Reductase from Rabbit Liver Microsomes with Detergents and Its Properties&lt;xref ref-type="fn" rid="fn1"&gt;&lt;sup&gt;*&lt;/sup&gt;&lt;/xref&gt;

NADH-Cytochrome b5 reductase [EC 1. 6. 2. 2] (fp1) was solubilized from rabbit liver microsomes with Triton X-100 and sodium deoxycholate and purified 30-fold in the presence of Triton X-100. This preparation was called ”detergent-solubilized fp1“ or simply ”d-fp1“ to distinguish it from the fp1 preparation purified after solubilization by lysosomal digestion (”lysosome-solubilized fp1“ or ”l-fp1“). The d-fp1 preparation still contained phospholipids and was contaminated by cytochromes P-450 and P-420, but was free from cytochrome b5 and NADPH-cytochrome c reductase system. A considerable amount of non-heme iron, showing an electron spin resonance (ESR) signal at g=4.3, was also present in the preparation, but this iron did not seem to be functional in the catalysis. When the preparation was subjected to Sephadex gel filtration in the presence of 1.0% deoxycholate, the reductase activity was eluted at a position corresponding to a molecular weight of 45,000. After treatment with lysosomes or partially purified cathepsin D, the elution volume of the reductase activity corresponded to a smaller molecular weight of about 28,000, which was similar to the value reported for l-fp1. d-fp1 could react with cytochrome b5 purified using detergent (“d-b5”) as well as with that solubilized by trypsin (“t-b5”) to reconstitute the NADH-cytochrome c reductase activity. However, it interacted with d-b5 much better than with t-b5. The highly efficient interaction with d-b5 was abolished when d-fp1 was digested with lysosomes or cathepsin D, though the reactivity of d-fp1 with t-b5 was unaffected by these treatments. It is suggested that the fp1 preparations obtained previously (l-fp1 are functionally incomplete.

Primary reactions of photosynthesis: photoreduction of a bound chloroplast ferredoxin at low temperature as detected by EPR spectroscopy.

An electron paramagnetic resonance signal was observed at 25 degrees K in whole spinach chloroplasts after illumination at 77 degrees K. The light-induced epr spectrum had g-values (g(x) = 1.86, g(y) = 1.94, g(z) = 2.05) and a temperature dependence that were characteristic of the reduced state of a plant-type ferredoxin. The light-induced epr spectrum was also observed in broken spinach chloroplasts from which soluble ferredoxin was removed. Chemical analyses showed that both whole and broken spinach chloroplasts contained amounts of nonheme iron and "acid-labile sulfide" consistent with the presence of a bound iron-sulfur protein, at a level of about one molecule per 75 chlorophyll molecules. These results support the conclusion that chloroplasts contain a bound ferredoxin that may serve as a primary low-potential electron acceptor in photosynthesis.