Is there a format suitable for importing amino acid sequences having D-Amino acids in them? If so, what does it look like or where can I find an example of it?
Although ST.25 sequence listings do not allow D-Amino acids, the definition of what is defined as an amino acid is expanded in ST.26 and ST.26 compliant-sequence listings require their inclusion. For an example, see Example 3(a)-1 in Annex VI of WIPO ST.26.
A sequence containing D-amino acids will be imported as any sequence containing only L-Amino acids. For information, each D-Amino acid must be annotated as prescribed in par. 29 and shown in par. 31. See as well the related examples from Annex VI, for instance Examples 29-1 and 30-1.