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UID:69dc174164e61
DTSTAMP:20260412T180553
DTSTART:20170203T110000
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DTEND:20170203T110000
URL:https://murmitoyen.com/events/vanille/udem/detail/737665-seminaire-de-l
 etudiant-scott-harroun-groupe-vallee-belisle
LOCATION:Pavillon Roger-Gaudry \, 2900\, boul. Édouard-Montpetit\, Local M
 -415\, Montréal\, QC\, Canada
SUMMARY:Séminaire de l'étudiant Scott Harroun ( Groupe Vallée-Belisle)
DESCRIPTION:Titre : Measurement of Exothermic Enzyme Activity-Induced Struc
 tural Destabilization
\nEndroit : Pavillon Roger-Gaudry\, salle G-415 à
  11 h 00.
\nCette conférence sera prononcée par Monsieur Scott Harroun\
 , étudiant au doctorat du laboratoire de Alexis Vallée-Belisle\, profes
 seur au Département de chimie de l'Université de Montréal.
\nRÉSUMÉ: 
 Despite much research into the evolution of enzymes\, some fundamental que
 stions remain unanswered. Recently\, several studies have reported enhance
 d diffusion of enzymes during exothermic catalysis\, but explaining this p
 henomenon has proven to be controversial. How does heat produced at the ac
 tive site diffuse into the surrounding medium? Can the heat released by an
  enzyme destabilize its structure\; in other words\, can the enzyme “ove
 rheat”? At present\, these questions are a matter of debate. In this pro
 ject\, we propose to use programmable DNA switches to measure structural d
 estabilization\, and possibly local temperature rise in the vicinity of an
  enzyme. ­The stability and melting temperature of these DNA switches can
  be readily tuned by varying the ratio of G-C to A-T base pairs in the ste
 m. Structures with more G-C base pairs in the stem have higher stability\,
  and thus unfold at higher temperatures. By attaching a fluorophore and qu
 encher pair at both extremities of the stem loop\, one can obtain a librar
 y of fluorescent switches. These DNA switches can also act as DNA nanother
 mometers\, with a specific linear dynamic range spanning 12°C. Accordingl
 y\, the DNA switch is anchored onto an enzyme to measure structural destab
 ilization and/or local rise in temperature due to heat released during the
  enzymatic reaction\, by monitoring fluorescence variation. Initial result
 s have found that the while the DNA switches attached to the enzyme are op
 ened during catalysis\, control DNA switches that are free in the solution
 \, but otherwise identical\, do not undergo such destabilization. The two 
 principle designs used herein involve coupling of biotinylated DNA switche
 s to streptavidin-modified alkaline phosphatase (AP)\, or to biotin-modifi
 ed AP with free streptavidin. AP was chosen because its enzymatic conversi
 on of para-nitrophenylphosphate to para-nitrophenol is highly exothermic\,
  and this enzyme has been reported elsewhere to undergo enhanced diffusion
  during this reaction. This project proposes to measure local change in te
 mperature to experimentally validate the rate of temperature diffusion\, a
 nd to determine if enzymes “overheat” and destabilize when functioning
  at high rates. As a future application\, by using these thermosensitive n
 anoswitches attached to enzymes\, it may be possible to trigger drug relea
 se via local temperature rise around an enzyme.
\nInformation supplémenta
 ireAnnonce PDF du séminaire
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