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. 2018 Feb 13;8:2950. doi: 10.1038/s41598-018-21408-8

Table 1.

MS detection of amide products formed by activation of l-tryptophan by TycA-A followed by nucleophilic substitution.

Substrate for TycA-A Nucleophile aProduct (mM) bConversion (%) Protonated parent ion (m/z) MS/MS fragment ion (m/z)
cType 1 dType 2
l-Tryptophan (Linear amines)
Methylamine 0.81 8.1 218.1302 58.0300 159.0923 87.0552 130.0655
Dimethylamine 0.81 8.1 232.0858 72.0446 159.0915 101.0705 130.0648
β-Alanine 0.96 9.6 276.1371 116.0508 159.0930 145.0653 130.0674
γ-Aminobutyric acid 1.16 11.6 290.1532 130.0663 159.0934 ND ND
(Cyclic amines)
Azetidine 0.82 8.2 244.1457 84.0450 159.0927 113.0713 130.0657
Pyrrolidine 0.92 9.2 258.1301 98.0598 159.0916 127.0863 130.0646
Piperidine 1.40 10.4 272.1783 112.0767 159.0930 141.1038 130.0661
Azepane 0.52 5.2 286.1944 126.0927 159.0933 155.1198 130.0663
Azocane 1.35 13.5 300.2090 140.1087 159.0936 169.1350 130.0665
(Cyclic amino acids and derivative)
d-Proline 0.46 4.6 302.1566 142.0647 159.0917 171.0760 130.0647
cis-4-Hydroxy-l-proline 0.94 9.4 318.1136 ND 159.0910 187.0707 130.0642
cis-4-Hydroxy-d-proline 0.78 7.8 318.1481 ND 159.0934 187.0742 130.0662
l-Prolinamide 0.85 8.5 301.1682 ND 159.0940 170.0626 130.0666
l-Azetidine-2-carboxylic acid 0.78 7.8 288.1772 128.0342 159.0918 157.0604 130.0649

ND, not detected

aCalculated from the amount of decrease in l-tryptophan minus the amount of l-tryptophyl-l-tryptophan generation.

bCalculated against the added l-tryptophan concentration.

cFragment ion generated by C1-C2 cleavage.

dFragment ion generated by C2-C3 cleavage.