PubMed · 3442365
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
L A Sternson. 1987. Obstacles to polypeptide delivery.. https://doi.org/10.1111/j.1749-6632.1987.tb45788.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Phytate-removed deamidated soybean globulins were prepared using ion-exchange resins to provide them with a functional property to enhance calcium absorption in the body. The phosphorus level was reduced from 45 to 20 micromol/g using 0.05 g/mL of AE-4, an anion-exchange resin with a (2-hydroxyethyl)dimethylammonium group, in 0.2% soybean globulin solution for 1 h at 4 degrees C, and 90-92% of the phosphorus in defatted soybeans could be removed. As for deamidation, CE-4, a cation-exchange resin of the carboxylate type, showed a much higher deamidation activity than CE-1 and CE-2, cation-exchange resins of the sulfonate type. No peptide bond hydrolysis was observed for any cation-exchange resin treated at 4 degrees C. There was no significant difference in the amount of acid amide deamidated at temperatures between 4 and 50 degrees C. The deamidation level was able to increase to 73% using 0.10 g/mL of CE-4 in a 0.2% soybean globulin solution for 6 h at 4 degrees C. The amount of calcium bound to the soybean globulins decreased with removal of the phytate but increased with deamidation.
Bioreduction of the well-crystallized ferric oxyhydroxide gamma-FeOOH lepidocrocite was investigated in batch cultures using Shewanella putrefaciens bacterium (strain CIP 8040) at initial pH 7.5 in bicarbonate buffer. The cultures were performed with formate as electron donor without phosphate, in the presence or absence of anthraquinone-2,6-disulfonate (AQDS) as electron shuttle. During lepidocrocite reduction, the iron(II,III) hydroxycarbonate green rust GR(CO32-) was characterized by X-ray diffraction, transmission electron microscopy, and transmission Mössbauer spectroscopy. The AQDS accelerated the kinetics of GR formation. GR was the major end product when bacterial reduction was not stopped by lack of electron donor, and between 55 and 86% of the iron from gamma-FeOOH precipitated in GR(CO32-). However, when the bacterial reduction was stopped by freezing/thawing or the electron donor was exhausted, the large quantity of remaining lepidocrocite induced a transformation of GR into magnetite. This confirms that GR is metastable with respect to magnetite in the presence of gamma-FeOOH.
Iron overload is a serious clinical condition which can be largely prevented by the use of iron-specific chelating agents. Desferrioxamine-B, the most widely used iron chelator in haematology over the past 30 years, has a major disadvantage of being orally inactive. Consequently, the successful design of an orally active, nontoxic, selective iron chelator has become a much sought after goal. In order to identify an ideal iron chelator for clinical use, a range of specifications must be considered such as metal selectivity and affinity, kinetic stability of the complex, bioavailability and toxicity. A wide range of chelator types bind iron(III) and of these, hexa-, tri-, and bidentate are capable of providing iron(III) with the favoured octahedral environment. In this review, the comparative properties of such ligands are discussed, examples being selected from hydroxamates, aminocarboxylates, hydroxypyridinones, orthosubstituted phenols and triazoles.