A consensus sequence is, in each case a version of the sequence having at each position the nucleotide (or amino acid) most commonly found there in different examples. Thus, the consensus sequence for promoters in E. coli recognized by RNA polymerase containing s70

TLS Online TPP Program

#Id: 7712

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                γ-Turn

Consists of 3 amino acids, generally termed as i, i + 1 and i + 2

H-bond is seen between i and i + 2 (First and Third residue)

The conformation of i + 1 is crucial and on the basis of this, they are classified into 2 groups

The dihedral angles of residue i + 1 are (70, -60) and (-70, 60) of the classical and inverse gamma turns

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#Id: 7713

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                        𝝅-Turn

Consists of 6 amino acids, generally termed as i, i + 1 , i + 2 i + 3 i + 4 and i + 5

H-bond is seen between i and i + 5 (First and sixth residue)

TLS Online TPP Program

#Id: 8443

#Unit 1. Molecules and their Interaction Relevant to Biology

The 3¹⁰ helix has 3 residues per tum and contains 10 atoms between the hydrogen bond donor and acceptor, hence its name.

TLS Online TPP Program

#Id: 8444

#Unit 1. Molecules and their Interaction Relevant to Biology

Both the pi helix and the 310 helix occur rarely and usually only at the ends of a helices or as single-tum helices. They are not energetically favorable, since the backbone atoms are too tightly packed in the 310 helix and so loosely packed in the n helix that there is a hole through the middle. 

Only in the a helix are the backbone atoms properly packed to provide a stable structure.

TLS Online TPP Program

#Id: 8445

#Unit 1. Molecules and their Interaction Relevant to Biology

Right-handed helical conformation has 3.6 residues per turn and 1.5A/aa.

TLS Online TPP Program

#Id: 8446

#Unit 1. Molecules and their Interaction Relevant to Biology

In the α helix, the backbone hydrogen bonds are arranged such that the peptide CO bond of the nth residue points along the helix axis toward the peptide NH group of the (n + 4)th residue.