Proteins and Enzymes

ID #2182

Are alpha helices considered polar and beta sheets considered polar? I am trying to understand why there are holes/plaques in tissues diagnosed with spongiform encephalopathies.

Alpha helices and beta sheets are both created by hydrogen bonding of main chain atoms. These hydrogen bonds develop from dipole moments in the N-H and C=O bonds. 

The "holes" that you find in the brain in prion diseases are due to aggregates of the protein when it is in its beta sheet form creating plaques that lead to neuronal cell death in that localized region. The protein aggregates much much more when it contains beta strands, because those strands group into beta sheets that interact with other beta sheets in the next prion protein. 

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