Which secondary structure is usual in normal prion proteins?

In the context of normal prion proteins, the presence of alpha helices is a key characteristic. These proteins typically exhibit a significant amount of alpha helical structure in their secondary formation when they are in their non-pathogenic state. Alpha helices are common structural motifs in proteins that contribute to their stability and functionality.

In the case of prion proteins, the normal form, designated as PrP^C, maintains a structure primarily rich in alpha helices. When prion proteins misfold into their pathogenic form, designated as PrP^Sc, there is a shift in the secondary structure, leading to an increase in beta-pleated sheets. This change in structural configuration is associated with the aggregation and neurotoxic properties of prion diseases.

Thus, understanding that normal prion proteins predominantly feature alpha helices highlights the importance of protein conformation in relation to function and pathology within prion biology.