From small-molecule reactions to protein folding: studying biochemical kinetics by stopped-flow electrospray mass spectrometry.
This work introduces stopped-flow electrospray ionization (ESI) mass spectrometry (MS) as a method for studying fast biochemical reaction kinetics. After initiating a reaction by rapid mixing of two solutions, the mixture is transferred to a reaction vessel and a steady liquid flow to the ESI source of the mass spectrometer is established. The kinetics are studied in real time by monitoring selected ion intensities as a function of time. In order to characterize the performance of this setup the acid-induced demetallation of chlorophyll a was studied. It was found that the reaction is second order in acid concentration and that pseudo-first-order rate constants of up to roughly 7 s(-1) can be measured reliably. Stopped-flow ESI MS was also applied to study the acid-induced denaturation of myoglobin. The data presented here confirm the occurrence of a short-lived unfolding intermediate during this reaction. Stopped-flow ESI MS can provide information that is not accessible by optical rapid-mixing experiments. Therefore it appears that this novel technique has the potential to become a standard tool for kinetic studies in a number of different fields.
Kolakowski
B M
BM
Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7, Canada.
Konermann
L
L
D002734:Chlorophyll / Q000737:chemistry*; D000077194:Chlorophyll A; D007700:Kinetics; D009211:Myoglobin / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013997:Time Factors
D009211:Myoglobin; D002734:Chlorophyll; D000077194:Chlorophyll A