Fig. 2

Most frequent nonsynonymous mutations of SARS-CoV-2 proteins and their corresponding trypsin-, Glu-C-, and neprosin-derived peptides. For the 37 most frequent nonsynonymous mutations, deletions (−) and terminations (*) (global frequency > 3%; [36]), 16 reside within the relatively short tryptic peptides (6–31 amino acids). Some of these tryptic peptides were experimentally detected by mass spectrometry [20, 29]. Additional 12 and 14 mutations could be independently detected within Glu-C- and neprosin-derived peptides, thus enabling quantification of ~ 89% of the most frequent SARS-CoV-2 mutations. The most frequent mutation D614G (~ 94%), as well as emerging variants of concern 20B/501Y.V1 (United Kingdom; S N501Y, S A570D, S HV69-, S D614G, ORF8 Q27*, N R203K, N G204R) and 20C/501Y.V2 (South Africa; S N501Y, S D614G) could be detected within the relatively short neprosin-derived peptides [38]