Quaternary Ammonium Salt as Promising Charge Reducing Agents for Gas Phase Proteins in Native Mass Spectrometry
Disciplines
Analytical Chemistry | Biochemistry
Abstract (300 words maximum)
Electrospray Ionization (ESI) is a process which utilizes high voltage in order to transfer the protein from solution into a gaseous phase producing multiple charge states. This ionization process results in the unfolding of the protein by disrupting the noncovalent interactions among subunits and secondary structures. Native mass spectrometry requires to preserve the noncovalent interactions in the gas phase protein while highly charged ions are generated from the electrospray ionization process. In this experiment, promising charge reducing agents of quaternary ammonium salts such as choline chloride (ChCl), tetra-n-butylammonium hydrate (TNBH), and betaine (BET) were investigated during the ESI process to determine their effectiveness as a charge reducing agent against the model protein lysozyme. All mass spectrometry experiments were conducted using high resolution Orbitrap Exploris 240 mass spectrometer. Initially, the control sample of Lysozyme was prepared in water, ammonium bicarbonate, ammonium acetate and acquired their mass spectrum. Various charge states from 5+ to 15+ were noticed for water soluble lysozyme sample where the most intense peak was noticed at 10+. The traditional charge reducing agents (ammonium bicarbonate, ammonium acetate) showed similar patterns although the strong peak is noticed at 8+. When chlorine chloride (ChCl) was added to the lysozyme sample, numerous high m/z peaks appeared in the spectrum including 3+ and 4+ charge states which were absent in the water and ammonium buffer samples. Similar trend is also noticed when betaine was added where 3+ and 4+ charge states also noticed. Nonetheless, various adducts were detected while high concentration of betaine was added. Moreover, tetra-n-butylammonium hydrate did not show any charge reduction. This study showed that chlorine chloride (ChCl) and betaine (BET) can be used as promising charge reducing agents although future experiments need to be directed for other proteins.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Mohammad A. Halim
Quaternary Ammonium Salt as Promising Charge Reducing Agents for Gas Phase Proteins in Native Mass Spectrometry
Electrospray Ionization (ESI) is a process which utilizes high voltage in order to transfer the protein from solution into a gaseous phase producing multiple charge states. This ionization process results in the unfolding of the protein by disrupting the noncovalent interactions among subunits and secondary structures. Native mass spectrometry requires to preserve the noncovalent interactions in the gas phase protein while highly charged ions are generated from the electrospray ionization process. In this experiment, promising charge reducing agents of quaternary ammonium salts such as choline chloride (ChCl), tetra-n-butylammonium hydrate (TNBH), and betaine (BET) were investigated during the ESI process to determine their effectiveness as a charge reducing agent against the model protein lysozyme. All mass spectrometry experiments were conducted using high resolution Orbitrap Exploris 240 mass spectrometer. Initially, the control sample of Lysozyme was prepared in water, ammonium bicarbonate, ammonium acetate and acquired their mass spectrum. Various charge states from 5+ to 15+ were noticed for water soluble lysozyme sample where the most intense peak was noticed at 10+. The traditional charge reducing agents (ammonium bicarbonate, ammonium acetate) showed similar patterns although the strong peak is noticed at 8+. When chlorine chloride (ChCl) was added to the lysozyme sample, numerous high m/z peaks appeared in the spectrum including 3+ and 4+ charge states which were absent in the water and ammonium buffer samples. Similar trend is also noticed when betaine was added where 3+ and 4+ charge states also noticed. Nonetheless, various adducts were detected while high concentration of betaine was added. Moreover, tetra-n-butylammonium hydrate did not show any charge reduction. This study showed that chlorine chloride (ChCl) and betaine (BET) can be used as promising charge reducing agents although future experiments need to be directed for other proteins.