title: Effects of polydisperse crowders on aggregation reactions: a molecular thermodynamic analysis.
abstract: Intracellular crowding in biological systems is usually mimicked in in vitro experiments by adding single crowders at high volume fractions, without taking into consideration the polydispersity of the crowders in the cellular environment. Here, we develop a molecular thermodynamic formalism to examine the effects of size-polydispersity of crowders on aggregation reaction equilibria. Although the predominantly common practice so far has been to appeal to the entropic (excluded-volume) effects in describing crowding effects, we show that the internal energy (hence, the enthalpy) of the system could dramatically alter the effects, even qualitatively, particularly in the case of a mixture of crowders, depending on the changes in the covolume of the products relative to that of the reactants and on the preferential binding or exclusion of the crowders by the reactants and products. We also show that in the case of polydisperse crowders the crowders with the largest size difference dominate the overall changes in the yield of the reaction, depending on the individual concentrations of the crowders.
authors.affiliation: Chemical & Pharmaceutical Engineering Program, The Singapore-MIT Alliance, National University of Singapore, Singapore 117576, Singapore. dhawal@nus.edu.sg
authors.forename: Dhawal
authors.initials: D
authors.lastname: Shah
authors.forename: Aik Lee
authors.initials: AL
authors.lastname: Tan
authors.forename: Vigneshwar
authors.initials: V
authors.lastname: Ramakrishnan
authors.forename: Jianwen
authors.initials: J
authors.lastname: Jiang
authors.forename: Raj
authors.initials: R
authors.lastname: Rajagopalan
mesh_terms: D011108:Polymers / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011108:Polymers