I need obtain taxonomy information(taxon id) of NCBI NR library by protein accession number. I find two useful files prot.accession2taxid.gz and pdb.accession2taxid.gz in https://ftp.ncbi.nlm.nih.gov/pub/taxonomy/accession2taxid/. However, some accession numbers still cannot fetch taxonomy information. Those accession numbers mainly are consist of the following categories:
The NCBI show "Record removed", like "AYN07615.1". Why did the records removed appear in the NR library?
Some accession numbers from unknown resources. For example, pir||S69889 and prf||1403304A.
Some accession numbers from PDB, but those cannot be found in pdb.accession2taxid.gz. For example 6F1U_FF
how can I obtain taxonomy information for those special accession numbers?