The catalytic active site of thioredoxin: conformation and homology with bovine pancreatic trypsin inhibitor.

Abstract

Rabbit polyclonal antibody was raised to a chemically synthesized nonapeptide (Trp-Ala-Glu-Trp-Cys-Gly-Pro-Cys-Lys) corresponding to the active-site sequence of Escherichia coli thioredoxin. The antiserum efficiently inhibited thioredoxin activity in the standard thioredoxin reductase/NADPH coupled assay. This inhibition was blocked by preincubation of the antiserum with the nonapeptide. Tight association of the E. coli thioredoxin to the active-site antibody required SDS denaturation. These results suggest that thioredoxin reductase (NADPH: oxidized-thioredoxin oxidoreductase, EC 1.6.4.5) alters the conformation of thioredoxin sufficiently to permit binding to the antibody. The antiserum bound to plant and liver thioredoxins. Bovine pancreatic trypsin inhibitor, whose active site (Gly-Pro-Cys-Lys) is homologous to that of thioredoxin, also competes for the active-site antibody. This result led to experiments showing that thioredoxin can inhibit the digestion of cytochrome c by trypsin. The ability of thioredoxin to act as a trypsin inhibitor analogue provides a rationale for thioredoxin's resistance to digestion by trypsin.

Statistics

0100200'04'05'06'07'08'09'10'11'12'13'14'15'16'17
Citations per Year

66 Citations

Semantic Scholar estimates that this publication has 66 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Lunn1986TheCA, title={The catalytic active site of thioredoxin: conformation and homology with bovine pancreatic trypsin inhibitor.}, author={Charles A. Lunn and Patricia Pak and John G Van Savage and V P Pigiet}, journal={Biochimica et biophysica acta}, year={1986}, volume={871 3}, pages={257-67} }