In situ observation of peptide bond formation at the water–air interface

Griffith, Elizabeth C.; Vaida, Veronica

doi:10.1073/pnas.1210029109

Cited by 150 publications

(166 citation statements)

References 41 publications

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“…Most notably, a new peak at 1645 cm −1 emerged after lengthening with glycine that corresponds to the Amide I peak related to the stretching of the carbonyl (C=O) of the amide bond [20] . The amide I peak was unique for the peptide bond formation because no such peak existed before mixing the glycine and the cysteamine-capped QDs.…”

Section: Resultsmentioning

confidence: 99%

Charge‐Neutral, Stable, Non‐Cytotoxic, Near‐Infrared SnS Aqueous Quantum Dots for High Signal‐to‐Noise‐Ratio Biomedical Imaging

Han

Shih

2017

ChemistrySelect

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We have synthesized charge-neutral, stable, non-cytotoxic, bright, near-infrared (NIR) SnS quantum dots (QDs) by first making Cysteamine-capped SnS QDs in glycerol under acidic conditions followed by lengthening the capping molecule with peptide bonds by reacting the capping molecules with glycine and subsequent heat treatment at 200°C for 4 hours. The obtained stable SnS QDs exhibited a band gap of 1.5 eV and a strong, narrow NIR emission peak at 830 nm with a quantum yield of 4.6%. The suspension could be stable for more than 1 month without aggregation or emission decay. The positively charged SnS QDs were further neutralized by 3-mercaptoproprionic acid (MPA) through electrostatic attraction. The MPA neutralized SnS QDs were shown to be non-cytotoxic at concentrations 6 times the typical QDs concentration for immunostaining. Low-noise, optimal NIR immunofluorescent imaging of vascular endothelial growth factor (VEGF) on 3T3 cells and Tn antigen on HT29 cells was achieved by using streptavidin (SA)-linked MPA-neutralized SnS QDs with a SA:QD molar ratio of 22:1 to bind to biotinylated secondary antibody bound on the primary antibody that was bound on the targeted antigen on the cell membrane with a high signal-to noise ratio (SNR) of 35.

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Section: Resultsmentioning

confidence: 99%

Charge‐Neutral, Stable, Non‐Cytotoxic, Near‐Infrared SnS Aqueous Quantum Dots for High Signal‐to‐Noise‐Ratio Biomedical Imaging

Han

Shih

2017

ChemistrySelect

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“…Again, a significant enhancement in reaction rate compared with the bulk was observed, and the rate was reported to be inversely proportional to the radius of the microdroplet. Clearly, these results have many important possible implications ranging from the kinetics of reactions inside a cell to the possible role confinement has played in the origin of life (39,41,42).…”

Section: Discussionmentioning

confidence: 99%

Microdroplet fusion mass spectrometry for fast reaction kinetics

Lee

Kim

Nam

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

210

258

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We investigated the fusion of high-speed liquid droplets as a way to record the kinetics of liquid-phase chemical reactions on the order of microseconds. Two streams of micrometer-size droplets collide with one another. The droplets that fused (13 μm in diameter) at the intersection of the two streams entered the heated capillary inlet of a mass spectrometer. The mass spectrum was recorded as a function of the distance x between the mass spectrometer inlet and the droplet fusion center. Fused droplet trajectories were imaged with a high-speed camera, revealing that the droplet fusion occurred approximately within a 500-μm radius from the droplet fusion center and both the size and the speed of the fused droplets remained relatively constant as they traveled from the droplet fusion center to the mass spectrometer inlet. Evidence is presented that the reaction effectively stops upon entering the heated inlet of the mass spectrometer. Thus, the reaction time was proportional to x and could be measured and manipulated by controlling the distance x. Kinetic studies were carried out in fused water droplets for acid-induced unfolding of cytochrome c and hydrogen-deuterium exchange in bradykinin. The kinetics of the former revealed the slowing of the unfolding rates at the early stage of the reaction within 50 μs. The hydrogendeuterium exchange revealed the existence of two distinct populations with fast and slow exchange rates. These studies demonstrated the power of this technique to detect reaction intermediates in fused liquid droplets with microsecond temporal resolution.mass spectrometry | liquid microdroplets | reaction kinetics | protein unfolding | hydrogen-deuterium isotope exchange T ime-resolved measurements of reaction intermediates are crucial for understanding the fast kinetics of chemical reactions. Various approaches have been implemented to improve the temporal resolution of kinetic measurements in liquid reactions (1, 2), which are often limited by the mixing time. One approach for improving the mixing time involves the use of turbulent flow to increase the shear stress in fluid channels (3). Another approach is to stimulate the rapid initiation of a reaction by photo-triggered initiation (4), electron transfer (5), or temperature jump/rise (6). A small-size reactor was also used for rapid mixing so that the time required for diffusion-dependent mixing is minimized (7-10).Among various methods for detecting reaction intermediates, mass spectrometry has been a powerful tool for probing reaction products because it can discriminate similar species by their mass-to-charge ratio while simultaneously measuring multiple species. Time-resolved mass spectrometry (11) has been widely used for measuring the kinetics of protein-ligand complexation, organometallic compound formation, and enzyme-catalyzed processes. Despite these efforts for improving temporal resolution, time-resolved mass spectrometry has been limited to the millisecond timescale, with a recent achievement of 300 μs (12).A major obstacle for imp...

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“…Hydrogen-bond interactions with water are interesting from a chemical perspective as well as playing central roles in biological, [1][2][3][4] geological, 5 and environmental 6-9 chemistry. Chemically, water is a responsive molecule 10 adapting due to interaction both with nearest neighbors as well as the larger environment.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Bonding between Water and Tetrahydrofuran Relevant to Clathrate Formation

Shultz

2014

J. Phys. Chem. B

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Tetrahydrofuran (THF) is well-known as a clathrate former as well as a promoter for gas hydrate formation. This work examines interactions between water and tetrahydrofuran via the effect on water's vibrational spectrum. Due to water's large oscillator strength in the hydrogen-bonded region, interactions are diagnosed by isolating small clusters in a transparent medium (carbon tetrachloride in this study). A weak THF/water hydrogen bond is reflected by a 3450 cm(-1) OH-donor vibration (blue shifted from the water/water hydrogen bond) and a 3685 cm(-1) nonbonded OH stretch (blue shifted 22 cm(-1) from the decoupled OH stretch in this medium). Increasing the THF concentration results in another 20 cm(-1) blue shift of the OH-donor stretch. Additional THF does not complex with free water but rather joins with existing THF/water structures to form a cluster enriched in THF. These results complement previous work examining THF vibrations in clathrate hydrates. Together, they generate a picture in which water mediates between THF pairs--mediation that affects vibrational frequencies of both species. In addition to a frequency shift, water's hydrogen-bonded resonance gains oscillator strength due to its mediating configuration.

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In situ observation of peptide bond formation at the water–air interface

Cited by 150 publications

References 41 publications

Charge‐Neutral, Stable, Non‐Cytotoxic, Near‐Infrared SnS Aqueous Quantum Dots for High Signal‐to‐Noise‐Ratio Biomedical Imaging

Charge‐Neutral, Stable, Non‐Cytotoxic, Near‐Infrared SnS Aqueous Quantum Dots for High Signal‐to‐Noise‐Ratio Biomedical Imaging

Microdroplet fusion mass spectrometry for fast reaction kinetics

Hydrogen Bonding between Water and Tetrahydrofuran Relevant to Clathrate Formation

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