Premium
A peptide model of insulin folding intermediate with one disulfide
Author(s) -
Yan Han,
Guo ZhanYun,
Gong XiaoWen,
Xi Dan,
Feng YouMin
Publication year - 2003
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.0237203
Subject(s) - peptide , folding (dsp implementation) , chemistry , disulfide bond , protein folding , oxidative folding , protein disulfide isomerase , biophysics , crystallography , biochemistry , biology , electrical engineering , engineering
Insulin folds into a unique three‐dimensional structure stabilized by three disulfide bonds. Our previous work suggested that during in vitro refolding of a recombinant single‐chain insulin (PIP) there exists a critical folding intermediate containing the single disulfide A20–B19. However, the intermediate cannot be trapped during refolding because once this disulfide is formed, the remaining folding process is very quick. To circumvent this difficulty, a model peptide ([A20‐B19]PIP) containing the single disulfide A20–B19 was prepared by protein engineering. The model peptide can be secreted from transformed yeast cells, but its secretion yield decreases 2–3 magnitudes compared with that of the wild‐type PIP. The physicochemical property analysis suggested that the model peptide adopts a partially folded conformation. In vitro, the fully reduced model peptide can quickly and efficiently form the disulfide A20–B19, which suggested that formation of the disulfide A20–B19 is kinetically preferred. In redox buffer, the model peptide is reduced gradually as the reduction potential is increased, while the disulfides of the wild‐type PIP are reduced in a cooperative manner. By analysis of the model peptide, it is possible to deduce the properties of the critical folding intermediate with the single disulfide A20–B19.