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The primary structure and properties of thioltransferase (glutaredoxin) from human red blood cells
Author(s) -
Papov Vladimir V.,
Gravina Stephen A.,
Mieyal John J.,
Biemann Klaus
Publication year - 1994
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560030307
Subject(s) - glutaredoxin , chemistry , physics , microbiology and biotechnology , biology , biochemistry , enzyme , glutathione
Abstract Thioltransferase (glutaredoxin) was purified from human red blood cells essentially as described previously (Mieyal JJ et al., 1991a, Biochemistry 30 :6088–6097). The primary sequence of the HPLC‐pure enzyme was determined by tandem mass spectrometry and found to represent a 105‐amino acid protein of molecular weight 11,688 Da. The physicochemical and catalytic properties of this enzyme are common to the group of proteins called glutaredoxins among the family of thiol: disulfide oxidoreductases that also includes thioredoxin and protein disulfide isomerase. Although this human red blood Cell glutaredoxin (hRBC Grx) is highly homologous to the 3 other mammalian Grx proteins whose sequences are known (calf thymus, rabbit bone marrow, and pig liver), there are a number of significant differences. Most notably an additional cysteine residue (Cys‐7) occurs near the N‐terminus of the human enzyme in place of a serine residue in the other proteins. In addition, residue 51 of hRBC Grx displayed a mixture of Asp and Asn. This result is consistent with isoelectric focusing analysis, which revealed 2 distinct bands for either the oxidized or reduced forms of the protein. Because the enzyme was prepared from blood combined from a number of individual donors, it is not clear whether this Asp/Asn ambiguity represents inter‐individual variation, gene duplication, or a deamidation artifact of purification.