Selective dissociation of non-covalent bonds in biological molecules by laser spray

✍ Scribed by Atsushi Takamizawa; Yoshiyuki Itoh; Ryo Osawa; Noriyuki Iwasaki; Yoshifumi Nishimura; Satoko Akashi; Kenzo Hiraoka

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 133 KB
• Volume: 39
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.677

✦ Synopsis

Abstract

The laser spray developed in our laboratory was applied to the analysis of bovine serum albumin (BSA), double‐stranded DNA (dsDNA) and a protein–DNA complex. The tip of a stainless‐steel capillary was irradiated with a 10.6 µm infrared laser by increasing the laser power from 0 W (electrospray) to 1.4 W. The laser beam was focused to about 0.3 mm at the tip of the stainless‐steel capillary. When BSA aqueous solution was irradiated by the laser, highly charged monomer ions were newly observed in addition to the multiply charged ions of non‐denatured monomer, dimer and trimer moieties. This indicates that BSA suffers from denaturation on irradiation with an infrared laser in solution. A 1.4 W laser power is not sufficient to cause the complete denaturation of BSA under the present experimental conditions. Whereas dsDNA was found to dissociate almost completely to single‐stranded DNA constituents on laser irradiation with a power of 1.2 W, no fragmentation of DNA molecules was observed. For a protein–DNA complex, i.e. a complex of c‐Myb DNA binding domain and dsDNA, dissociation of the complex to the component moieties was observed. These findings indicate that the laser spray can selectively dissociate non‐covalent complexes into subunits without causing dissociation of the covalent bonds of the subunits. The laser spray will be a versatile method for the investigation of the structures and stabilities of biomolecules including non‐covalent complexes. Copyright © 2004 John Wiley & Sons, Ltd.