[institut] SCL seminar: Natasa Adzic, Thursday, 6 October 2016, 14:00

[Marija Mitrovic Dankulov]

Dear colleagues,

You are cordially invited to the Scientific Computing Laboratory 
seminar, which will be held on Thursday, 6 October 2016 at 14:00 in the 
library reading room “Dr. Dragan Popović" of the Institute of Physics 
Belgrade.

The talk title:

Phenomenology of electrostatic interactions in protein physics

The talk will be given by Dr. Nataša Adžić from Jožef Stefan Institute, 
Ljubljana, Slovenia.

Abstract of the talk:

In the world of proteins one can find exotic electrostatic phenomena 
such as long- ranged attraction between two electro-neutral protein 
particles in an aqueous solution, stemming from thermal charge 
fluctuations of dissociable charge groups on their surface. It was first 
observed by Kirkwood and Schumaker, half a century ago, who described it 
in the framework of statistical mechanical perturbation  theory and 
showed that this interaction scales different from standard van der 
Waals interaction [1,2]. Inspired by the work of Kirkwood and Shumaker, 
we were investigating the interaction that they had proposed in a more 
general theoretic framework, obtaining the results also valid in the 
regimes where the original derivation fails. The general idea was to 
broaden the existing modern field-theoretic approach to the statistical 
mechanics of Coulomb fluid [3], by including within this framework the 
concept of charge regulation in the form of an additional field-depended 
general surface free energy. Charge regulation implies that the 
effective charge on a macroion, e.g. protein surface, responds to the 
local solution conditions, such as local pH, local electrostatic 
potential, salt concentration, dielectric constant variation and most 
importantly the presence of other vicinal charged groups. Although this 
is an old concept, modern theories of electrostatic interaction beetween 
macroions immersed in Coulomb fluids mostly deal with constant surface 
charge of a macroion, bypassing the complications introduced by charge 
regulation. We present a theoretical framework that allows to 
consistently generalize the ideas of Kirkwood and Shumaker, or indeed of 
any electrostatic interaction that includes charge regulation, in such a 
way that one can use advanced concepts and methods of the Coulomb fluid 
statistical mechanics in order to analyze its salient features in 
various regions of the parameter space [4,5,6].

[1] J. Kirkwood and J.B. Shumaker, Proc. Natl. Acad. Sci. USA 38 855 
(1952).
[2] J. Kirkwood and J.B. Shumaker, Proc. Natl. Acad. Sci. USA 38 863 
(1952).
[3] A. Naji, M. Kanduc, J. Forsman, and R. Podgornik, J. Chem. Phys. 
139, 150901 (2013).
[4] N. Adžic and R. Podgornik, Euro. Phys. J. E 37, 49 (2014).
[5] N. Adžic and R. Podgornik, Phys. Rev. E 91, 022715 (2015).
[6] N. Adžic and R. Podgornik, J. Chem. Phys. 144, 214901 (2016).

Best regards,
Marija Mitrović Dankulov


-- 
Marija Mitrovic Dankulov
E-mail: mitrovic at ipb.ac.rs

Phone: +381 11 3713068
Fax: +381 11 3162190

Scientific Computing Laboratory
Institute of Physics Belgrade
Pregrevica 118, 11080 Belgrade, Serbia