Thioredoxin-linked peroxidase from human red blood cell: evidence for the existence of thioredoxin and thioredoxin reductase in human red blood cell.

A thiol-dependent antioxidant protein (HRPRP) was previously reported as a predominant antioxidant protein in human red blood cell (RBC). The analysis of amino acid sequence of HRPRP with those of human PRP-like gene products indicates that HRPRP is identical to brain PRP (HPRP). This protein act as a peroxidase linked to thioredoxin (Trx)/thioredoxin reductase (TR). Until now, there was no evidence for Trx/TR system in RBC. The existence of the Trx/TR system in RBC was immunologically determined. A 58-kDa protein showing TR activity was partially purified from human RBC and characterized. Our results reveal that HRPRP act as a new type of peroxidase supported by Trx/TR system in human RBC.