Conformational change of proteins probed by laser spray

There is an exciting scientific research on the protein conformation studied by newly-developed laser spray ionization source, which was reported by Xiangguo Shi et al in Rapid communication in Mass Spectrometry this month.

Horse heart cytochrome c (cyt c, Protein Data Bank (PDB) ID: 1HRS) is a small heme protein, whose molecular weight is 12,365, with 104 amino acid residues and plays an important role in transferring electrons in the respiratory chain. In the reported study, they used cyt c as a model protein to establish the methodology in the conformational study.

Laser spray was developed by Hiraoka and coworkers in Yamanshi University (Japan) is a hybrid of three basic techniques for the generation of gaseous ions from the condensed phase. Laser spray mass spectrometry can faithfully reflect the solution-phase characteristics of biomolecules. Xiangguo Shi and coworkers have successfully applied laser spray to evaluate the binding affinities of protein-DNA and drug-DNA complexes. One of the advantages of laser spray in the analysis of biomolecules is its convenience. Laser spray provides information on the stability of biomolecules instantly just by tuning the laser power. In this recent work, they investigated whether laser spray could be employed to analyze the thermal stability and folding transitions of proteins quantitatively. The stability of horse heart cytochrome c and bovine ubiquitin was evaluated by laser spray and compared in this study.

In the study, they have demonstrated that laser spray mass spectrometry can conveniently provide thermal denaturation profiles of proteins such as cyt c. A good correlation was found between Tm, determined by CD, and E50%, determined by laser spray mass spectrometry. The thermal stabilities of ubiquitin and cyt c prepared in solutions at the same pH were also easily differentiated by ranking the E50% values. Their exciting studies indicate that laser spray mass spectrometry could be a versatile method for rapid evaluation of the thermal stability of proteins, and for observation of conformational changes by a simple tuning of the laser power.

Electrospray was often used to identify and analyze biological macromolecules and developed by John Bennett Fenn and coworkers. Dr. Fenn (born June 15, 1917 in New York City) was awarded the Nobel Prize in Chemistry in 2002. Does laser spray have more advantages than electrospray? Is it possible that Hiraoka and coworkers win the Nobel Prize in the near future? We are looking forward to the new excited scientific discovery on laser spray.