Detection of Molecular Ions of Non-Covalent Complexes of Ras·GDP and Ras·GppNp by MALDI-TOFMS

抄録

A detection of non-covalent complexes of Ras·GDP and Ras·GppNp (guanosine-5′-(β,γ-imido)-triphosphate; GTP analogue) using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS) is reported. The Ras proteins are bound to GDP or GppNp, non-covalently, with ionic bonds. The GDP-bound Ras is inactive, while the GTP-bound Ras is active. This paper shows the possibility of the detection of the active and inactive form of a regulatory protein, which is non-covalently bound with a nucleotide, with a small sample amount by MALDI-TOFMS analyses. It was also suggested that MALDI-TOFMS is promising for the estimation of the ratio of nucleotide bound Ras protein and free apo-Ras protein.