Protein biochemistry
Protein analysis of collected fluids of various Nepenthes species
using SDS–PAGE of TCA-precipitated proteins followed by in-gel
tryptic digestion, desalting and concentration (ZipTip columns,
C18-RP, Millipore, Schwalbach, Germany) and subsequent
micro-sequencing of peptides obtained was done exactly as
described (Rottloff et al., 2011). Expression of the recombinant
NmPR-1 protein in stably transfected Sf9 cells (NmPR-1/Sf9)
was analyzed by Western blot after SDS–PAGE and transfer of
the proteins on PVDF-membranes using the anti-V5 horseradish
peroxidase antibody (Invitrogen) for detection. For treatments of
PR-1/Sf9 protein, either 8 M urea or the peptide-N-glycosidase
PNGase F (NEB, Frankfurt/Main, Germany) was used following
exactly the manufacturer’s protocol. Such experiments were
analyzed via Western blot using an anti-V5 horseradish