Glutathione Reductase from Human Erythrocytes. Amino-Acid Sequence of a Major Fragment that Links the FAD, NADP and Interface Domains

A major CNBr fragment of glutathione reductase, peptide Q [Krohne-Ehrich, G., Schirmer, R.H. & Untucht-Grau, R. (1977) Eur. J. Biochem. 80, 65-71], was further fractionated by trypsin, chymotrypsin, thermolysin and clostripain digestion. The peptides were isolated and most of them were sequenced by solid-phase Edman degradation. The whole peptide Q was sequenced N-terminally up to position 51 by the same technique. A total sequence of 128 amino acids (28% of the whole protein) was obtained and could be localized in the electron density map [Schulz, G.E., Schirmer, R.H., Sachsenheimer, W. & Pai, E.F. (1978) Nature (Lond.) 273, 120-124] from position 259-387. This part of the polypeptide links and participates in all three domains of the flavoenzyme.