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. 2015 May 27;5:10637. doi: 10.1038/srep10637

Table 1. Chromatographic and Mass Spectrometric Data Oligodepsipeptides (DP2a/b – DP12) and their Methyl and Ethyl esters Released from B. cereus Cultures upon Extraction with MeCN/H2O (70/30, v/v), MeOH, and EtOH, Respectively.

No.a Peptides (R=H) and Peptide Esters (R=Me, Et)b UPLC-TOF MS data
    free peptidesc
 methyl esterd
 ethyl estere
 13C-labeled ethyl esterf
    RTg(min) ECh (EM/AM; var., ppm)i RTg (min) ECh (EM/AM; var., ppm)i RTg(min) ECh (EM/AMh; var., ppm)i RTg(min) ECh (EM/AMh; var., ppm)i
DP2a D-O-Leu-D-Ala-O-R 0.97 C9H17NO4Na (226.1055/226.1055; -0.1) 1.00 C10H19NO4Na (240.1212/240.1211; +0.1) 1.05 C11H21NO4Na (254.1368/254.1377; +3.5) — —
DP2b L-O-Val-L-Val-O-R 0.99 C10H19NO4Na (240.1212/240.1211; -0.1) 1.05 C11H21NO4Na (254.1368/254.1373; +2.0) 1.12 C12H23NO4Na (268.1525/268.1537; +4.5) — —
DP4 L-O-Val-L-Val-D-O-Leu-D-Ala-O-R 1.10 C19H34N2O7Na (425.2264/425.2265; +0.2) 1.17 C20H36N2O7Na (439.2420/439.2420; -0.1) 1.24 C21H38N2O7Na (453.2577/453.2569; -1.8) 1.24 12C1913C2H38N2O7Na (455.2644/455.2645; -1.8)
DP6a D-O-Leu-D-Ala-(L-O-Val-L-Val-D-O-Leu-D-Ala)-O-R 1.14 C28H49N3O10Na (610.3316/610.3323; +1.1) 1.28 C29H51N3O10Na (624.3472/624.3477; +0.8) 1.35 C30H53N3O10Na (638.3629/638.3628; -0.2) 1.35 12C2813C2H53N3O10Na (640.3696/640.3688; -1.2)
DP6b (L-O-Val-L-Val-D-O-Leu-D-Ala)-L-O-Val-L-Val-O-R 1.22 C29H51N3O10Na (624.3472/624.3472; -0.3) 1.45 C30H53N3O10Na (638.3629/638.3635; +0.9) 1.52 C31H55N3O10Na (652.3785/652.3777; -1.2) 1.52 12C2713C4H55N3O10Na (656.3919/656.3916; -0.5)
DP8 (L-O-Val-L-Val-D-O-Leu-D-Ala)2-O-R 1.43 C38H66N4O13Na (809.4524/809.4530; +0.7) 1.75 C39H68N4O13Na (823.4681/823.4688; +0.9) 1.78 C40H70N4O13Na (837.4837/837.4798; -4.7) 1.78 12C3613C4H70N4O13Na (841.4971/841.4961; -1.2)
DP10a D-O-Leu-D-Ala-(L-O-Val-L-Val-D-O-Leu-D-Ala)2-ORj 1.44 C47H81N5O16Na (994.5576/994.5580; +0.4) 1.97 C48H83N5O16Na (1008.5733/1008.5740; +0.7) 1.95 C49H85N5O16Na (1022.5889/1022.5871; -1.8) 1.94 12C4513C4H85N5O16Na (1026.6023/1026.6012; -1.1)
DP10b (L-O-Val-L-Val-D-O-Leu-D-Ala)2-L-O-Val-L-Val-O-R 1.54 C48H83N5O16Na (1008.5733/1008.5735; +0.2) 2.32 C49H85N5O16Na (1022.5889/1022.5897; +0.8) 2.26 C50H87N5O16Na (1036.6046/1036.6031; -1.4) 2.21 12C4413C6H87N5O16Na (1042.6247/1042.6244; -0.3)
DP12 (L-O-Val-L-Val-D-O-Leu-D-Ala)3-O-R 1.78 C57H98N6O19Na (1193.6784/1193.6787; +0.3) 2.99 C58H100N6O19Na (1207.6941/1207.6953; +1.0) 2.71 C59H102N6O19Na (1221.7097/1221.7050; -3.8) 2.68 12C5313C6H102N6O19Na (1227.7299/1227.726; -3.1)

aCompound number of peptides detected; bSequence of open-chain peptides and peptide esters determined my MSn analysis; c,d,e Corresponding peptides and esters released upon treatment of B. cereus cell pellets with MeCN/H2O (70/30, v/v), MeOH, and EtOH, respectively; f 13C-Labeled ethyl esters released of strain F4810/72 cultivated in MOD-medium supplemented with 13C1-valine;17,19 g Retention time on RP-18 UPLC; h Elemental composition of analyte; i Exact mass (EM, calcd) and accurate mass (AM) of analyte’s [M+Na]+ ion determined by means of TOF MS.