Unnatural/non-standard amino acids are those which are not found incorporated in the proteins and peptides produced naturally. These differ from the commonly identified set of 22 naturally occurring amino acids.

PepEngine provides detailed structural information along with visual aids and references to allow further explorations. Below are some of the highlighted features of the database:

• A comprehensive search function which includes conformational search.
• In-built 3D-structural visualization for all peptides.
• Downloadable structures of peptides in multiple formats.
• References for each peptide to enable further independent research.

The available peptides can be downloaded in two formats: SDF and PDB.

There are multiple implications of PepEngine database:

• As a repertoire of structural motifs formed by peptides.
• As a starting point for further explorations towards the structural aspect of non-standard peptides.
• As a validation tool for computational techniques such as conformational sampling and predicting minimum energy states.

PepEngine may be beneficial for Biophysicists, X-ray crystallographers, Computational structural biologists, Protein/Peptide engineers etc.

Currently the PepEngine database contains detailed structural information of 99 non-standard peptides containing α,β-dehydrophenylalanine (Δ-Phe) and α-aminoisobutyric acid (Aib) along with their original references.

We plan to continuously expand the database with the following:

• Addition of newly discovered peptides along with their detailed structural information.
• Incorporating more classes of non-standard amino acids.
• Setting up an automatic text-mining pipeline to scour for novel peptides.

The details regarding whom to contact for addition of a peptide to the database or for providing suggestions/improvements can be found on the contact/contribute page.