Both crowding and confinement give rise to the folding temperature and the folding stability of protein. It is shown that the folding free energy change due to crowding in the confined condition can be fitted to Minton scaled particle theory by assuming a linear dependence of the effective radius of the protein unfolded state on the volume fraction of crowders. | Communications in Physics, Vol. 28, No. 4 (2018), pp. 351-360 DOI: ADDITIVE EFFECTS OF MACROMOLECULAR CROWDING AND CONFINEMENT ON PROTEIN STABILITY PHUONG THUY BUI1,† AND TRINH XUAN HOANG2,3 1 Duy Tan University, 254 Nguyen Van Linh, Thanh Khe, Da Nang, Viet Nam 2 Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Ha Noi, Viet Nam 3 Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Viet Nam † E-mail: buiphuongthuyphys@ Received 16 October 2018 Accepted for publication 30 November 2018 Published 15 December 2018 Abstract. Folding of protein in vivo typically occurs in a solution highly crowded by macromolecules and in a confined space. It has been found that the effects of macromolecular crowding and confinement are similar in terms of the enhancement of protein stability. However, these effects are often considered separately in theoretical and simulation studies. In this study, by using coarse-grained models and Langevin dynamics, we show that the two effects are additive to each other when they are both present. Both crowding and confinement give rise to the folding temperature and the folding stability of protein. It is shown that the folding free energy change due to crowding in the confined condition can be fitted to Minton scaled particle theory by assuming a linear dependence of the effective radius of the protein unfolded state on the volume fraction of crowders. Keywords: confinement, crowding, molecular dynamics, protein folding. Classification numbers: ; . c 2018 Vietnam Academy of Science and Technology 352 P. T. BUI AND T. X. HOANG I. INTRODUCTION The cytosol of a living cell is crowded by a large number of macromolecules including many proteins, ribonucleic acids (RNAs) and their soluble complexes, which occupy up to 40% of the cytosolic volume. Furthermore, subcellular .
