Folding of protein fragments: conformational and biological studies on thioredoxin and its fragments.

Abstract

AbstractThioredoxin can be cleaved enzymatically into the two fragments (1–73) and (74–108) and chemically into two different ones (1–37) and (38–108). In this paper, the conformational properties of the short fragment (1–37) are reported and compared with those of the larger fragment (1–73). Using mainly circular dichroism (CD), it is shown that the (1–37) fragment, which contains the active disulfide unit center, is present as an unordered structure in the neutral pH range, but assumes a rigid folding at pH values below 6. The form of the CD spectrum is very similar to that of the complete native protein, and to that of the folded (1–73) fragment. The possible mechanisms for refolding of the short fragment are discussed.