3 years ago

Rapid Hydrogen–Deuterium Exchange in Liquid Droplets

Rapid Hydrogen–Deuterium Exchange in Liquid Droplets
Juan G. Santiago, Yin-Hung Lai, Richard N. Zare, Erik T. Jansson
The rate of hydrogen–deuterium exchange (HDX) in aqueous droplets of phenethylamine has been determined with submillisecond temporal resolution by mass spectrometry using nanoelectrospray ionization with a theta-capillary. The average speed of the microdroplets is measured using microparticle image velocimetry. The droplet travel time is varied from 20 to 320 μs by changing the distance between the emitter and the heated inlet to the mass spectrometer and the voltage applied to the emitter source. The droplets were found to accelerate by ∼30% during their observable travel time. Our droplet imaging shows that the theta-capillary produces two Taylor cone–jets (one per channel), causing mixing to take place from droplet fusion in the Taylor spray zone. Phenethylamine (ϕCH2CH2NH2) was chosen to study because it has only one functional group (−NH2) that undergoes rapid HDX. We model the HDX with a system of ordinary differential equations. The rate constant for the formation of −NH2D+ from −NH3+ is 3660 ± 290 s–1, and the rate constant for the formation of −NHD2+ from −NH2D+ is 3330 ± 270 s–1. The observed rates are about 3 times faster than what has been reported for rapidly exchangeable peptide side-chain groups in bulk measurements using stopped-flow kinetics and NMR spectroscopy. We also applied this technique to determine the HDX rates for a small 10-residue peptide, angiotensin I, in aqueous droplets, from which we found a 7-fold acceleration of HDX in the droplet compared to that in bulk solution.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b03541

DOI: 10.1021/jacs.7b03541

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.