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Physics Seminar

On the Left handed helices
by Dr. Kiran B. Chilakamarri, Texas Southern University
2008-05-07, 10:00 AM in NSB



The “Dictionary of protein secondary structure” identifies an exhaustive set of eight secondary structures in protein. Helices, beta-sheets, and random coils are very popular structures from among the eight structures. Helices and random coils are local structures while beta-sheets are built from far flung protein segments. According to the traditional wisdom helices in a protein are either left handed or right handed. However, our studies have shown that there are a good number of helices are not pure and that they contain both left and right handed parts. We christen them as mixed helices. In addition to being left or right handed helices in proteins are further classified into three types 310-helix, α-helix and π-helix based on how tightly the helix is wound. It is well known that the right handed helices dominate in number. We have gone through the DSSP data looking for the left handed helices in 35,000 proteins. In this talk we will the results of this search. This talk is aimed at anyone who is interested in protein structure. I will give an exploratory talk on the structure of folded proteins and introduce the Protein Data Bank (PDB) and the DSSP program (Define Secondary Structure of Proteins).