A Novel Hydrophobicity Scale Derived from Membrane Protein Folding into Phospholipid Vesicles - Chemistry Seminar

Dr Karen Fleming of John Hopkins University will be presenting a seminar entitled, "A Novel Hydrophobicity Scale Derived from Membrane Protein Folding into Phospholipid Vesicles."

Abstract:
The protein-folding problem is one of the great challenges of contemporary biology. Knowing how the sequence for a protein encodes its fold would open a world of possibilities to molecular sciences that would no doubt include insights into evolution, genetic diseases as well as the ability to engineer proteins with novel functions. While soluble protein folding has been investigated for decades, similar studies on membrane proteins are, by comparison, in their infancy.
 
We have overcome many technical obstacles to successfully determine the thermodynamic stability of several membrane proteins. In dissecting transmembrane protein stability, we have discovered a novel hydrophobicity scale, and – for the first time – we are able to derive sequence–structure–energy relationships for a set of membrane proteins. Our progress has been enabled using the transmembrane beta-barrel, a protein fold that is uniquely suited for these investigations. However, we show that our findings are applicable to transmembrane alpha-helical proteins as well.
 
We are further investigating the dynamical process undergone by proteins as they insert into membranes. How is it that a membrane protein can be trafficked to its native membrane and know to fold there? By conducting kinetic experiments of the folding pathway both in the presence and absence of cellular assembly factors, we are able to propose and are testing functional roles for biological chaperones.
 
For more information about Dr. Fleming and her research, click here.
 
Faculty Host: Dr. Wei
Date:
-
Location:
CP-137

Dynamics of Polyatomic Free Radical Reactions - Chemistry Seminar

Dr Floyd Davis of Cornell University will be presenting a seminar entitled, "Dynamics of Polyatomic Free Radical Reactions."

Abtract: This talk will highlight two recent studies at Cornell aimed at better understanding the fundamental principles underlying chemical reactivity. Using the crossed molecular beams method, an atomic or molecular beam containing a highly reactive species is crossed with a second beam containing a stable molecule. The angular and velocity distributions of the neutral products from single reactive collisions are measured using mass spectrometry employing “soft” single photon ionization using pulsed vacuum ultraviolet light.

Vibrational vs. Translational Energy in Promoting a Metal-Hydrocarbon Insertion Reaction: 

There have been many previous studies of the role of vibrational energy in promoting abstraction reactions (e.g., Cl + CH4 → HCl + CH3). However, there have been very few studies of how vibrational energy promotes reactions initiated by insertion. The reactions of early transition metal atoms (Y, Nb, Zr, Mo) with simple hydrocarbons are simple prototypes for understanding hydrocarbon C-H and C-C bond activation. Previous work has shown that the reaction Y + CH4 → HYCH3 → YCH2 + H2 (Y = yttrium) is initiated by C-H insertion involving a 20 ± 3 kcal/mol potential energy barrier. In the present work, the reaction is studied in crossed molecular beams under two different conditions with nearly the same total energy. One experiment is carried out at a collision energy of 15.1 kcal/mol with one quantum of CH4 antisymmetric (ν3) stretching vibrational excitation (8.63 kcal/mol), the other at a collision energy of 23.8 kcal/mol. Our results are compared with results from other groups focusing on dissociative adsorption of CH4 on metal surfaces.

Collision Complex Lifetimes in the C6H5 + O2 Reaction: Does RRKM Theory Apply?

The reaction of phenyl radicals (C6H5) with molecular oxygen (O2) has been investigated at a range of collision energies. Here we detect the formation of the phenoxy radical, C6H5O from the C6H5O + O channel. The measured distributions imply that the reaction proceeds through formation of long-lived (τ >>1 ps) phenylperoxy intermediates, C6H5OO, followed by simple O-O bond fission. The interpretation of our measurements employing a pulsed C6H5 beam produced by 193 nm photodissociation of C6H5Cl sharply contrasts those of recent crossed beams investigations in which the C6H5 reactants were produced by pyrolysis of C6H5NO.

For more information about Dr. Davis and his research, click here.

Faculty Host: Dr. Yang
Date:
-
Location:
CP-137

Throat Singing Demonstration

WHO: Dr. Theodore Levin and Sayan Bapa (Huun-Huur-Tu)

WHAT: Throat singing demonstration and discussion of musical aspects of Huun Huur Tu's music

WHERE: Briggs Theater, UK Fine Arts Building

WHEN: Saturday October 8, 3:30p.m.

 

Free and open to the public

Date:
-
Location:
Briggs Theater, UK Fine Arts Building

Music and Ritual Himalayan Music

WHO: Pritam Bhartwan

WHAT: An exploration of the joyful and ecstatic devotional music from the central Himalayas of India with musician and healer Pritam Bhartwan

WHEN:October 6, 2011 7:00p.m.

WHERE: Niles Gallery, Lucille Caudill Little Fine Arts Library

 

Date:
-
Location:
Niles Gallery, Lucille Caudill Little Library
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