Table III Verification of completeness of digestion for the SIAQSIEK, LGVILPVTK, and LIYGIPQLIEYK quantitative peptide transitions. For 15N PAD MS measurements, 5.0 × 105 CFU ml−1 of spiked S. aureus was subjected to phage amplification, tryptic digest, and LC-MS/MS analysis. Triplicate results for each preparation are shown and intra-peptide and inter-peptide means (CFU ml−1 tested), standard deviations, and percent relative standard deviations (% RSDs) for n = 3 sample preparations is reported. S.D. = standard deviation; % RSD = % relative standard deviation
3-min Digestion Protocol (5 × 105 CFU ml−1 spiked S. aureus)
n = 33-min 15N PAD Digest 13-min 15N PAD Digest 23-min 15N PAD Digest 33-min 15N PAD Digest Intra-peptide (mean ± S.D.) (% RSD)3-min 15 N PAD Digest Inter-peptide (mean ± S.D.) (% RSD)
SIAQSIEK5.33 × 1055.55 × 1054.84 × 1055.24 × 105 ± 3.64 × 104 (6.95)5.00 × 105 ± 2.09 × 104 (4.18)
LGVILPVTK4.83 × 1055.03 × 1054.86 × 1054.91 × 105 ± 1.06 × 104 (2.18)
LIYGIPQLIEYK4.72 × 1055.20 × 1054.64 × 1054.85 × 105 5 ± 3.05 × 104 (6.29)
2-h Digestion Protocol (5 × 105 CFU ml−1 spiked S. aureus)
n = 32-h 15N PAD Digest 12-h 15N PAD Digest 22-h 15N PAD Digest 32-h 15N PAD Digest Intra-peptide (mean ± S.D.) (% RSD)2-h 15N PAD Digest Inter-peptide (mean ± S.D.) (% RSD)
SIAQSIEK4.74 × 1054.19 × 1054.73 × 1054.56 × 105 ± 3.13 × 104 (6.86)4.74 × 105 ± 1.82 × 104 (3.83)
LGVILPVTK4.96 × 1054.66 × 1055.14 × 1054.92 × 105 ± 2.39 × 104 (4.85)
LIYGIPQLIEYK4.80 × 1054.57 × 1054.90 × 1054.76 × 105 ± 1.69 × 104 (3.56)
Overnight Digestion Protocol (5 × 105 CFU ml−1 spiked S. aureus)
n = 3Overnight 15N PAD Digest 1Overnight 15N PAD Digest 2Overnight 15N PAD Digest 3Overnight 15N PAD Digest Intra-peptide (mean ± S.D.) (% RSD)Overnight 15N PAD Digest Inter-peptide (mean ± S.D.) (% RSD)
SIAQSIEK5.42 × 1056.47 × 1055.60 × 1055.83 × 105 ± 5.64 × 104 (9.67)5.67 × 105 ± 1.48 × 104 (2.61)
LGVILPVTK5.06 × 1056.38 × 1055.53 × 1055.66 × 105 ± 6.70 × 104 (11.84)
LIYGIPQLIEYK5.04 × 1056.30 × 1055.26 × 1055.54 × 105 ± 6.74 × 104 (12.17)