Peptoid Calculator is a peptoid chemical formula and molecular weight calculator and MS peak assignment tool.

Peptoid sequences can be entered using the multiple-letter building block codes listed below. Residues should be separated by dashes and repeat sequences indicated using parentheses, for example:

Nspe((NLys-Nspe-Nspe)2-NLys-Nspe)3-NLys

N- and C-termini can be selected from the predefined lists. Peptoid Calculator also accepts custom termini entered as chemical formulae.

MS peaks for assignment can be provided in the form of a comma-separated list and Peptoid Calculator will attempt to assign them to deletion sequences and/or adducts.

A ChemDraw file is automatically generated for each peptoid sequence entered, and can be downloaded via a link on the results page. It may be necessary to increase the document size in order to view the complete structure.

Predefined termini and building blocks currently supported are given below (with chemical formulae). Hovering over underlined building block codes will display molecular structures.

Please note that due to the implementation of a new naming scheme, formulae for the building blocks NTyr, NTrp, NArg, NHis and NCys have changed as of 16/09/15. In addition, the codes NNVa and NHLe have been replaced by NnVal and NhLeu respectively.

For information on building block naming please see the Peptoid Calculator building block nomenclature guidance.

The calculation functions of Peptoid Calculator can also be used in Microsoft Excel, see the add-in page for more information.

Please send comments, questions, residue requests and bug reports to:

Peptoid building block library data compiled by Hannah Bolt.