It is well known that the single proline can adopt two structural configurations: the cis and the trans configurations. Polyproline, which contains multiple proline units, has been shown to exist as two types of conformations: polyproline I (PPI), which is composed of only cis prolines linked in a right handed helix fashion, and polyproline II (PPII), which is constructed with only trans prolines connected in left handed helix form, exhibiting a more elongated structure. Here we explored the time-dependent transition between PPI and PPII using the model system of polyproline 7 (Pro7) and polyproline 13 (Pro13) by ion mobility spectrometry-mass spectrometry (IMS-MS). For both Pro7 and Pro 13, the transition from PPI to PPII was faster than in the reverse direction. In addition, the transitions between PPI and PPII were faster for Pro7 than that for Pro13, indicating the length effect on structural transitions. The experimental data showed no intermediate between PPI and PPII transition of Pro 7; However, multiple intermediates were found during the transition of Pro13. The transitions of polyproline provided significant insight into the structural stability of PPI and PPII helices.

Time-dependence scan for structural transitions of polyproline

246th National Meeting (2013)

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