Figure 5.

Reaction of [d₅]-DA-LppK58A-strep with Lnt and Lit. [d₅]-DA-LppK58A-strep purified from reactions with membranes containing Lnt (from strain KA893; panels A and B) or Lit (from strain KA801; panels D and E) were digested with trypsin and analyzed by MALDI-TOF MS. B, the MS/MS spectrum of the sodiated parent triacylated 1428.3 u ion yielded the dehydroalanyl ion at 814.1 u, indicating an unlabeled N-acyl chain on LppK58A-strep (C). E, MS/MS of the sodiated parent ion diacylated 1189.9 u ion from Lit generated a dehydroalanyl ion at 816.2 u, consistent with a lyso-LP chemotype containing a [d₅]-labeled N-acyl chain (F).