BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//RLASKEY//CALENDEROUS//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260817T071334Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20081204T200000Z
DTEND:20081204T210000Z
UID:event348@bu.edu
URL:http://physics.bu.edu/internal/events/show/348
SUMMARY:Control of protein folding and misfolding in ionic liquid media\, a
	nd a conjecture on early earth biology
DESCRIPTION:Featuring C. Austen Angell\, Arizona State University\nHosted b
	y: H. Eugene Stanley\n\nPart of the Biophysics/Condensed Matter Seminar Ser
	ies.\n\nAbstract:\nWe describe recent studies [1-4] in which many of the co
	mplex features of biomolecule behavior\, such as protein folding and fibril
	lization\, are reproduced (with little change from biological behavior) in 
	hydrated (10-20 wt % water) protic ionic liquid solutions (PILs) in which t
	he water activity is only a small fraction of its normal value. An outstand
	ing finding of these studies has been the stabilization against the normal 
	deteriorating influences of aggregation and hydrolysis\, of model proteins 
	like lysozyme and ribonuclease A\, when in the PILs environment. To charact
	erize the protein stability we define a "refoldability"\, or "refolding ind
	ex" (RFI)\, which is the percentage of a protein that refolds after an unfo
	lding scan conducted in a differential scanning calorimeter at 20K/min\, fo
	llowed by intrument cooling. This percentage is determined by comparison of
	 first and second unfolding endotherms\, RFI =100∆Hd2/∆Hd1 and\, for th
	e above proteins in their stable zones\, is 97-99. \nWe then show how the p
	roton activity in the (H3O+-free) PIL can be characterized by the NMR chemi
	cal shift of the lone proton on a PIL cation\, such as diethylmethylammoniu
	m\, δ(N-H). This varies greatly as the anion is changed from acetate to pe
	rchlorate. High RFI zones are found for certain δ(N-H) ranges4 \, and fibr
	illization is observed when δ(N-H) of the solvent PIL lies far outside the
	se stable ranges [3]. \nThe fact that these high concentration ionic media 
	stabilize proteins against deterioration (and loss of bioactivity as determ
	ined on dilution) strikes a chord of interest in the light of Phillip Ballâ
	€™s commentary\, in his book "Life’s Matrix: a biography of water" [5]\, 
	on the difficulties confronting the common "primordial soup" theories of th
	e origin of life in which complex biomolecules are considered to form by sp
	ontaneous association in the organic precursor-containing\, aqueous\, matri
	x. How could molecules such as the proteins and RNAs arise in the face of t
	heir unfavorable hydrolysis rates\, ask critics. With an interest in this q
	uestion we enquire into whether such syntheses could arise in ambient tempe
	rature media that are friendly to biomolecules by virtue of the presence of
	 water only at low activity. We find that the simplest protic ionic liquids
	\, ammonium nitrate and ammonium acetate\, PILs whose component acid and ba
	se members can form by primitive natural routes\, are ambient temperature l
	iquids in the presence of 20 wt% water\, and that the proteins of our study
	 dissolve in them readily\, without denaturing. While they do not denature 
	at ambient temperature\, they are not stabilized in these simple media: onc
	e thermally unfolded\, they do not refold (i.e. the RFI = 0). However\, on 
	introduction of just 10% of the simple organic cation salt ethylammonium ni
	trate\, the stability\, assessed by the RFA\, becomes as high as any observ
	ed in the previous studies [6]\, suggesting that such non-hydrolyzing liqui
	ds could have served as biogenesis media in the distant past. \n1.1. N. Byr
	ne\, L.-M. Wang\, J.-P. Belieres\, CAA\, Chem. Commun. 2714\, (2007) \n2.2.
	 N. Byrne and C. A. Angell\, J. Mol. Biol\, 378\,. 707. (2008) \n3.3. N. By
	rne and C. A. Angell\, (Chem. Commun. In press) \n4.4. Angell\, C. A. Byrne
	\, N.\, and Belieres\, J.-P. Acc. Chem. Res. 40\, 1228\, (2007) \n5.5. Ball
	\, P. "Life’s Matrix: a biography of water"\, 1999. \n6.6. N. Byrne\, J-P
	. Belieres and C. A. Angell.. (Aust. J. Chem. submitted).
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR