Athanor by arbastro
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How to open a HELM string

Press / for Quick insert, paste a HELM string such as PEPTIDE1{A.C.D.E}$$, and choose Build from HELM. The sequence builder opens with it; press Insert.

HELM (Hierarchical Editing Language for Macromolecules) writes peptides and nucleic acids as chains of monomers, for example PEPTIDE1{A.C.D.E}$$.

Steps

  1. Press / for Quick insert.

  2. Paste the HELM string. Quick insert offers Build from HELM.

    Quick insert offering Build from HELM for PEPTIDE1{A.C.D.E}$$.Quick insert offering Build from HELM for PEPTIDE1{A.C.D.E}$$.

  3. Choose Build from HELM. The sequence builder opens with the string and reads it back: the residue count, the sequence, the formula and the molar mass.

    Build from sequence with 4 residues, H-Ala-Cys-Asp-Glu-OH, C15H24N4O9S, 436.44 g/mol.Build from sequence with 4 residues, H-Ala-Cys-Asp-Glu-OH, C15H24N4O9S, 436.44 g/mol.

  4. Press Insert.

The builder's options, such as drawing residues or the full structure, are on Build from a sequence. Monomers it knows are listed in Monomers.

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Last updated Nov 12, 2026