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TLS Online TPP Program

#Id: 4914



#Unit 1. Structure and Function of Biomolecules #Enzyme Inhibition #Part B Pointers
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TLS Online TPP Program

#Id: 8464

#Unit 1. Structure and Function of Biomolecules

The overall effect is a significant net dipole for the a helix that gives a partial positive charge at the amino end and a partial negative charge at the carboxy end of the a helix. 
TLS Online TPP Program

#Id: 8465

#Unit 1. Structure and Function of Biomolecules

The magnitude of this dipole moment corresponds to about 0.5-0.7 unit charge at each end of the helix. These charges would be expected to attract ligands of opposite charge and negatively charged ligands, especially when they contain phosphate groups and frequently bind at the N-termini of a helices. In contrast, positively charged ligands rarely bind at the C-terminus
TLS Online TPP Program

#Id: 8466

#Unit 1. Structure and Function of Biomolecules

Polyleucine and polyalanine readily form a-helical structures.
TLS Online TPP Program

#Id: 8467

#Unit 1. Structure and Function of Biomolecules

polylysine is a random coil at pH values below about 11, where repulsion of positive charges prevents helix formation. At pH 12, where polylysine is a neutral peptide chain, it readily forms an a-helix.
TLS Online TPP Program

#Id: 8468

#Unit 1. Structure and Function of Biomolecules

polyGlu is a random coil at pH values above about 5, where repulsion of negative charges prevents helix formation. 
TLS Online TPP Program

#Id: 8469

#Unit 1. Structure and Function of Biomolecules

The RHH (L amino acids) α helix, which ideally has ϕ = −57° and ψ = −47°