Serum Proteins and Vanadyl Compounds

A likely difference in the metabolism of free and chelated sources lies in post-absorptive processes, particularly transport in the bloodstream. The study of the interactions of insulin-enhancing compounds with serum proteins has been almost exclusively studied by EPR. Apo-transferrin and albumin have been implicated in the transport of vanadyl ions in the blood, and these proteins represent a significant metal-binding capability in the blood. Considerable interest in the role of these proteins in the transport and biotransformation of administered vanadium compounds has been evident in the recent literature. 

Chasteen and coworkers conducted extensive studies on the interactions of VOSO4 with apo-transferrin (apo-Tf) and albumin (HSA) by EPR [31,50,74-77]. This body of work underpins all current studies of these proteins with insulinenhancing compounds but will not be reviewed here. 

Peak width° (G) Relative peak area B A (Area(B)/Area(A),%) 

Investigations have also been made into the interactions of vanadyl complexes and albumin by EPR. Willsky et al. reported that a complex formed between 

VO(ma)2 and HSA was dissimilar to the one made between VOSO4 and HAS [79]. Further insight into formation of this new eomplex, and a potential key difference 

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