Hi, I am trying to visualize several of the secondary structure details on a protein of interest, and I recently had notice (by several research papers) about the existence of a left-handed helix on it. However, I could not detect the helix using UCSF Chimera (it is simply considered as a loop). Why could this happen and how could be resolved? I have tried to modify the ksdssp cut-off parameter, but it was unsuccessful, so I think now that maybe the specific nature of the helix (left-handed polyproline-like type II) could be a bit tricky for the program. What would you suggest? Thanks in advance for your help an patience. Best regards, *Andrés Felipe Vásquez J., BSc, MSc.* Grupo de Fisiología Molecular Subdirección de Investigación Científica y Tecnológica Dirección de Investigación en Salud Pública Instituto Nacional de Salud Avenida calle 26 No. 51-20 - Zona 6 CAN +57 (1) 2207700 ext. 1419 Bogotá, D.C., Colombia