Iron absorption data comparison

The same reaction sequence was monitored by uv-visible spectroscopy and despite the lack of optical data for the zerovalent binary iron-isocyanide complexes, comparison with the spectrum for FeCCO) (18) reveals a close similarity. After the photolysis the original spectrum [an intense absorption at 232 nm with two shoulders at 297 and 340 nm] had decayed to be replaced by a new spectrum consisting of two bands at 220 and 382 nm. 

With the exact role of lactoferrin uncertain and the mechanism of iron absorption also unknown, the concentration of iron and other trace elements in human milk is a controversal item. The data involving iron levels in breast milk date from the early fifties to the present time. During the stage of lactation, colostrum, early and mature milk samples are known to decrease in iron concentration with time, see Table II (17,18). The comparison of mature breast milk, 7 days or older, finds a range in iron concentration from 0.21 to 1.28 mg/liter. Weekly, daily and diurinal variation within a given day were demonstrated for iron, copper and zinc in human milk samples (20). Great variations were found within a given day on total yield, fat, and mineral levels (17,20). 

Position assessed by method of Iwata, et al., reference 83. Mobility assessed by comparisons of anomalous Fe peak heights data collected at or near the iron K absorption edge. (See references 84 and 88.) ... 

A band of this type has been observed for an enzyme-substrate complex ES where the enzyme was represented by the oxidized form of peroxidase cytochrome c, cyt(Fe(III)) and the substrate was the reduced form of cytochrome c, cytj (Fe(II)) [298]. Indeed, on mixing the solution of cyt(Fe(I I)) and cytj (Fe(II)) there appeared a new absorption band with the absorption maximum at Emax = 1.4 eV, the extinction coefficient e = 0.35 M-1 cm-1, and the width a = 0.2 eV. This band was referred [298] to charge transfer via electron tunneling, [cyt(Fe(III))/ cyt, (Fe(II))] -> [cyt(Fe(II))/cytl(Fe(III))]. From a comparison of the data on the intensity of this band with the results of fluorescence measurements, the distance between the iron atoms Fe(III) and Fe (II) in the [cyt(Fe(III))/cyt1(Fe(II))] complex has been estimated to be R 15-20 A and the edge-to-edge tunneling distance Rt = 7 A. 

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