Fe3+ is converted to Fe2+, which is bound and transported in the body via circulating transferrin. In pathogenic _Neisseria_, ferric iron-binding protein serves as the main periplasmic-protein for ferric iron that has equivalence to human transferrin. Once in the cytosol, ferric iron is stored in ferritin where it is associated with hydroxide and phosphate anions.
Iron absorption and systemic iron homeostasis are regulated by hepcidin, which is a peptide hormone that also regulates the activity of the iron-efflux protein, ferroportin-1. Iron is mostly absorbed in the duodenum and upper jejunum. Fe3+ displays low solubility at the neutral pH of the intestine and is mainly be converted to ferrous iron (Fe2+) by ferric reductases, as ferric salts are only half as well absorbed as ferrous salts. Once converted in the intestinal lumen, Fe+2 is transported across the apical membrane of enterocytes. The absorption rate of non-haem iron is 2-20%. Stored iron may be liberated via ferroportin-mediated efflux, which is coupled by reoxidation of Fe2+ to Fe3+ by ceruloplasmin in the serum or hephaestin in the enterocyte membrane. Fe3+ subsequently binds to transferrin, which keeps ferric cation in a redox-inert state and delivers it into tissues. It is proposed that there may be separate cellular uptake pathways for ferrous iron and ferric iron. While ferrous iron is primarily carried by divalent metal transporter-1 (DMAT-1), cellular uptake of ferric iron is predominantly mediated by beta-3 integrin and mobilferrin, which is also referred to as calreticulin in some sources as a homologue. However, the most dominant pathway in humans is unclear.
Iron is predominantly conserved in the body with no physiologic mechanism for excretion of excess iron from the body, other than blood loss. The pharmacokinetic properties of ferric compounds vary.
Less than 65% of iron is stored in the liver, spleen, and bone marrow, mainly as ferritin and haemosiderin. The pharmacokinetic properties of ferric compounds vary.
来源:DrugBank
吸收、分配和排泄
清除
铁损失率大约为每天1毫克。铁化合物的药代动力学特性各不相同。
The rate of iron loss is approximately 1 mg/day. The pharmacokinetic properties of ferric compounds vary.
Conformational Studies on the Δ<sup>8</sup>(<i>E</i>,<i>Z</i>)-Sphingolipid Desaturase from <i>Helianthus annuus</i> with Chiral Fluoropalmitic Acids As Mechanistic Probes
The Δ8-sphingolipid desaturase from sunflower (Helianthus annuus) converts phytosphinganine into a mixture of Δ8-(E)- and -(Z)-phytosphingenines by removal of two syn-hydrogen atoms from anti-, and gauche-conformations of the substrate. With chiral (R)-6-, (S)-6-, (R)-7-, and (S)-7-fluoropalmitic acids the importance of conformations for the formation of (E)- and (Z)-isomers was investigated by using
Process for producing ferrogmagnetic iron oxide powder comprising a
申请人:Fuji Photo Film Co., Ltd.
公开号:US04125474A1
公开(公告)日:1978-11-14
In a process for producing a ferromagnetic powder having a high coercive force which comprises adding an aqueous solution containing Co.sup.+2 ions, or both Co.sup.+2 ions and another cation(s), and an alkali solution to a suspension of a ferromagnetic iron oxide containing the metal(s) given by these ion(s), the improvement wherein said ferromagnetic iron oxide is treated with a reducing agent prior to the preparation of the suspension.
作者:Oliver Einsle、Albrecht Messerschmidt、Petra Stach、Gleb P. Bourenkov、Hans D. Bartunik、Robert Huber、Peter M. H. Kroneck
DOI:10.1038/22802
日期:1999.7
The enzyme cytochrome c nitrite reductase catalyses the six-electron reduction of nitrite to ammonia as one of the key stepsin the biological nitrogen cycle1, where it participates inthe anaerobic energy metabolism of dissimilatory nitrate ammonification2. Here we report on the crystal structure of this enzyme from the microorganism Sulfurospirillum deleyianum, which we solved by multiwavelength anomalous dispersion methods. We propose a reaction scheme for the transformation of nitrite based on structural and spectroscopic information. Cytochrome c nitrite reductase is a functional dimer, with 10 close-packed haem groups of type c and an unusual lysine-coordinated high-spin haem at the active site. By comparing the haem arrangement of this nitrite reductase with that of other multihaem cytochromes, we have been able to identify a family of proteins in which the orientation of haem groups is conserved whereas structure and function are not.
细胞色素 c 亚硝酸还原酶催化亚硝酸六电子还原为氨,是生物氮循环的关键步骤之一1,它参与厌氧能量代谢的硝酸盐氨化异化作用2。在此,我们报告了来自 Sulfurospirillum deleyianum 微生物的这种酶的晶体结构,并通过多波长反常色散方法解决了这一问题。我们根据结构和光谱信息提出了亚硝酸盐转化的反应方案。细胞色素 c 亚硝酸盐还原酶是一个功能性二聚体,在活性位点上有 10 个紧密排列的 c 型血红素基团和一个不寻常的赖氨酸配位的高自旋血红素。通过将这种亚硝酸盐还原酶的血红素排列与其他多血红素细胞色素的血红素排列进行比较,我们发现了一个蛋白质家族,在这个家族中,血红素基团的取向是保守的,而结构和功能则是不保守的。
Thiosulfate Dehydrogenase (TsdA) from Allochromatium vinosum
作者:José A. Brito、Kevin Denkmann、Inês A.C. Pereira、Margarida Archer、Christiane Dahl
DOI:10.1074/jbc.m114.623397
日期:2015.4
Although the oxidative condensation of two thiosulfate anions to tetrathionate constitutes a well documented and significant part of the natural sulfur cycle, little is known about the enzymes catalyzing this reaction. In the purple sulfur bacterium Allochromatium vinosum, the reaction is catalyzed by the periplasmic diheme c-type cytochrome thiosulfate dehydrogenase (TsdA). Here, we report the crystal
Electron Accepting Units of the Diheme Cytochrome c TsdA, a Bifunctional Thiosulfate Dehydrogenase/Tetrathionate Reductase
作者:Julia M. Kurth、José A. Brito、Jula Reuter、Alexander Flegler、Tobias Koch、Thomas Franke、Eva-Maria Klein、Sam F. Rowe、Julea N. Butt、Kevin Denkmann、Inês A.C. Pereira、Margarida Archer、Christiane Dahl
DOI:10.1074/jbc.m116.753863
日期:2016.11
In the oxidized state, this tetraheme cytochromec contains three hemes with axial His/Met ligation, while heme 3 exhibits the His/Cys coordination typical for TsdA active sites. Interestingly, thiosulfate is covalently bound to Cys330 on heme 3. In several bacteria including Allochromatium vinosum, TsdB is not present, precluding a general and essential role for electron flow. Both, AvTsdA and the