In humans, there are three RAS, three Raf, two MEK, and two MAP proteins.

TLS Online TPP Program

#Id: 8467

#Unit 1. Molecules and their Interaction Relevant to Biology

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. Molecules and their Interaction Relevant to Biology

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. Molecules and their Interaction Relevant to Biology

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

TLS Online TPP Program

#Id: 8470

#Unit 1. Molecules and their Interaction Relevant to Biology

The two forms of poly(Pro)

all cis (I) or all trans (II) peptide bonds. 

poly(Pro) I as a right-handed helix with 3.3 residues per turn 

poly(Pro) II is a left-handed helix with 3 residues per turn.

TLS Online TPP Program

#Id: 8471

#Unit 1. Molecules and their Interaction Relevant to Biology

poly(Pro) helix are stabilized by water molecule hydrogen bonding

TLS Online TPP Program

#Id: 8472

#Unit 1. Molecules and their Interaction Relevant to Biology

Poly(Gly) chains also adopt secondary conformations. 

In the solid state poly(Gly) has been shown to adopt two regular conformations designated I and II. 

State I has an extended conformation like a β strand whilst state II has three resides per turn and is similar to poly(Pro).