JMSSJ On-line

JMSSJ On-line, Vol. 44 (1996) No. 2, pp. 269-277

Detection of Molecular Ions of Non-Covalent Complexes of Ras·GDP and Ras·GppNp by MALDI-TOFMS		>> Full Text PDF >> References
*Satoko AKASHI,^a) Mikako SHIROUZU,^b) Shigeyuki YOKOYAMA,^{b), c)} and Koji TAKIO^a)** ^a) Division of Biomolecular Characterization, The Institute of Physical and Chemical Research (RIKEN), (2-1 Hirosawa, Wako, Saitama 351-01, Japan)* ^b) Cellular Signaling Laboratory, The Institute of Physical and Chemical Research (RIKEN), (2-1 Hirosawa, Wako, Saitama 351-01, Japan) ^c) Department of Biophysics and Biochemistry, Faculty of Science, The University of Tokyo (Hongo, Bunkyo-ku, Tokyo 113, Japan)

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.

Key words: Ras, Non-covalent complex, MALDI-TOFMS