Is human thioredoxin monomeric or dimeric?
We have examined the molecular weight and rotational correlation time of human thioredoxin by analytical ultracentrifugation and NMR spectroscopy, respectively. Two variants of human thioredoxin were studied, namely human thioredoxin identical in amino acid sequence to the one whose NMR structure we previously determined (C62A, C69A, C73A, M74T) and human thioredoxin (C62A, C69A, C73A, M74) containing the wild-type amino acid methionine at position 74. In both cases, the experimental data indicate that the predominant species is monomeric and we find no evidence for the existence of a well-defined dimeric form as was observed in the recently reported crystal structure (Weichsel et al., 1996) of human thioredoxin and the C73S mutant.
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA. gronenborn@vger.niddk.nih.gov
A M
AM
Gronenborn
G M
GM
Clore
J M
JM
Louis
P T
PT
Wingfield
D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008715:Methionine / Q000032:analysis; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013879:Thioredoxins / Q000737:chemistry*; D013912:Threonine / Q000032:analysis; D014461:Ultracentrifugation
D013912:Threonine; D013879:Thioredoxins; D008715:Methionine