Glutaredoxins, also known as thioltransferases (disulphide reductases, are small proteins of approximately one hundred amino-acid residues which utilise glutathione and NADPH as cofactors. Oxidized glutathione is regenerated by glutathione reductase. Together these components compose the glutathione system. Glutaredoxin functions as an electron carrier in the glutathione-dependent synthesis of deoxyribonucleotides by the enzyme ribonucleotide reductase. Like thioredoxin, glutaredoxin possesses an active centre disulphide bond. It exists in either a reduced or an oxidized form where the two cysteine residues are linked in an intramolecular disulphide bond. This family includes the highly abundant Escherichia coli GrxB (Grx2) glutaredoxin which is notably longer than either GrxA or GrxC. Unlike the other two E. coli glutaredoxins, GrxB appears to be unable to reduce ribonucleotide reductase, and may have more to do with resistance to redox stress. The only available structure was solution structure (PDB code 1G7O). Presented crystal structure of the GrxB from Salmonella typhimurium is structurally similar (sequence similarity 86%) to the glutaredoxin from Escherichia coli. High resolution crystal structure of the complex of the GrxB with the glutathione is a important step in understanding of the mechanism of the reaction.