Detection of Secondary Structures from 3D Protein Images of Medium Resolutions and its Challenges

Protein secondary structures such as α-helices and β-strands are major structural components in most proteins. The position of secondary structures provides important constraints in computing the tertiary structure of a protein. Electron cryomicroscopy is a biophysical technique that produces 3-dimensional images of large molecular complexes. For images at medium resolutions, such as 5–10 A, major secondary structures may be computationally detected. This paper summarizes our recent work in detection of secondary structures using SSETracer, SSELearner, StrandTwister and StrandRoller. The detection of helices and β-strands is illustrated using SSETracer and StrandTwister with a small dataset.