Pep-Calc.com: a set of web utilities for the calculation of peptide and peptoid properties and automatic mass spectral peak assignment.

The ability to calculate molecular properties such as molecular weights, isoelectric points, and extinction coefficients is vital for scientists using and/or synthesizing peptides and peptoids for research. A suite of two web utilities: Peptide Calculator and Peptoid Calculator, available free at http://www.pep-calc.com, are presented. Both tools allow the calculation of peptide/peptoid chemical formulae and molecular weight, ChemDraw structure file export and automatic assignment of mass spectral peaks to deletion sequences and metal/protecting group adducts. Peptide Calculator also provides a calculated isoelectric point, molar extinction coefficient, graphical peptide charge summary and β-strand contiguity profile (for aggregation-prone sequences), indicating potential regions of synthesis difficulty. In addition to the unique automatic spectral assignment features offered across both utilities, Peptoid Calculator represents a first-of-a-kind resource for researchers in the field of peptoid science. With a constantly expanding database of over 120 amino acids, non-natural peptide building blocks and peptoid building blocks, it is anticipated that Pep-Calc.com will act as a valuable asset to those working on the synthesis and/or application of peptides and peptoids in the biophysical and life sciences fields.