English: Image used in Peptidomimetics wikipedia page. Figure 2. An L-peptide and its analogues. An L-peptide (1) sequence has three analogues: the D-enantiomer (3) with the same sequence, the retro L-peptide (4) with the inverted sequence, and the retro-inverso D-peptide(2), with all D-amino acids and the inverted sequence. In this image (1) and (3) are shown from C-terminus on the left to N-terminus on the right, while (2) and (4) are shown from N-terminus to C-terminus. Note that (1) and (2) have similar side chain positions; one is the retro-inverso sequence of the other. The same applies to (3) and (4).