The possible importance of tryptophan in binding in SARS-CoV-2 is exemplified in the following sequence of the SARS-CoV-2 S1-NTD section of the spike glycoprotein (including the signal peptide, in order to conserve standard numbering). The sequence is from the S1-NTD of SARS-CoV-2 GenBank entry MN908947.3, along with a brief description of accessibility in PDB entry 6VVX, which is for the spike protein in the closed state.