Influence of transferrin glycans on receptor binding and iron-donation.

Human bi-bi-antennary transferrin (Tf) was partially deglycosylated by subsequently incubating with one or more of the following exoglycosidases: neuraminidase, beta-galactosidase or N-Acetyl-beta-D-glucosaminidase. Aglyco-Tf obtained from serum of a patient suffering from the Carbohydrate Deficient Glycoprotein syndrome was isolated. Receptor binding and the Tf and iron uptake capacities of the fully glycosylated-, partially deglycosylated- and aglyco-Tf were compared using the human hepatoma cell line PLC/PRF/5.

Isolation, purification and characterization of porcine serum transferrin and hemopexin.

Two techniques are described for the isolation of porcine serum transferrin and hemopexin, respectively, yielding nearly pure proteins (> 99%) as tested with crossed immunoelectrophoresis. Porcine transferrin has an estimated molecular weight of 79 kDa and porcine hemopexin a molecular weight of 62 kDa. Both purified proteins were subjected to amino acid and carbohydrate analyses.

Adaptation of transferrin protein and glycan synthesis.

We report the patterns of variability in transferrin structure in pregnancy, iron deficiency anemia, women using oral contraceptives, nonanaemic rheumatoid arthritis, iron deficient rheumatoid arthritis and anemia of the chronic diseases. Changes in microheterogeneity were assessed by crossed immuno isoelectric focusing of serum transferrin. Intra-individual variation in the control group was minimal.

Effect of phlebotomy on the ferritin iron content in the rat liver as determined morphometrically with the use of electron energy loss spectroscopy.

Phlebotomy of untreated and iron-loaded rats results in a significant decrease in total liver iron. In iron-loaded rats a marked decrease in iron-containing particles is observed ultrastructurally in lysosomes and cytoplasm of hepatic sinusoidal cells but not in parenchymal cells. This remarkable phenomenon was further investigated in a morphometric study, based on element-specific (iron) distribution images made in situ in the parenchymal cell by means of electron energy loss spectroscopy.

Release of iron from endosomes is an early step in the transferrin cycle.

Transferrin bound to K 562 cells at 4 degrees C was internalized quickly on temperature shift to 37 degrees C. Endosomes were isolated according to two different procedures. The endosome fraction was shown to be heterogeneous and consisted of two vesicle populations, differing in density properties and iron content.