SAP in the egg jelly of the sea urchin Arbacia punctulata 

Resact (14-amino acid chemotactic peptide)

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).

TLS Online TPP Program

#Id: 8473

#Unit 1. Molecules and their Interaction Relevant to Biology

Beta sheets usually have their B strands either parallel or antiparallel

TLS Online TPP Program

#Id: 8474

#Unit 1. Molecules and their Interaction Relevant to Biology

β Sheets in proteins contain 2 to as many as 22 polypeptide strands, with an average of 6 strands. 

Each strand may contain up to 15 residues, the average being 6 residues.