Ionization basis for activation of enzymes soluble in ionic liquids

TY - JOUR

T1 - Ionization basis for activation of enzymes soluble in ionic liquids

AU - Ou, Guangnan

AU - He, Biyan

AU - Halling, Peter

PY - 2016/7/1

Y1 - 2016/7/1

N2 - BACKGROUND: The complex interactions between electrolytes and proteins have been studied for more than a century. However, understanding is not yet complete and does not provide a basis for predicting the activity of enzymes in ionic media. The use of ionic liquids (ILs) as reaction medium has opened up new opportunities for better understanding of the mechanism of enzymatic catalysis. Although a number of properties of ILs have been correlated with enzyme function, these relationships are not completely understood at a molecular level. METHODS: We propose that ILs must be able to promote ionization of protein ionizable groups in order to dissolve active enzymes. The biocompatible IL need to possess a functional group with large donor number and acceptor number in both cationic and anionic units, each of which is based on a high dielectric constant lead structure. We designed and synthesized two series of ILs and determined their ionizing-dissociating abilities and activities of lipases soluble in these new ILs. RESULTS: The results showed that the ionizing-dissociating abilities of ILs paralleled the catalytic activity trend of lipases dissolved in the ILs. The activities of lipases soluble in the newly designed ILs were comparable to those in water. CONCLUSIONS: We can conclude that ionizing-dissociating abilities of an IL can be used as a basis for predicting the activity of enzymes soluble in the IL. GENERAL SIGNIFICANCE: Ionization basis for activation of enzymes gives a deeper understanding of the behavior of enzymes in non-aqueous media at a molecular level.

AB - BACKGROUND: The complex interactions between electrolytes and proteins have been studied for more than a century. However, understanding is not yet complete and does not provide a basis for predicting the activity of enzymes in ionic media. The use of ionic liquids (ILs) as reaction medium has opened up new opportunities for better understanding of the mechanism of enzymatic catalysis. Although a number of properties of ILs have been correlated with enzyme function, these relationships are not completely understood at a molecular level. METHODS: We propose that ILs must be able to promote ionization of protein ionizable groups in order to dissolve active enzymes. The biocompatible IL need to possess a functional group with large donor number and acceptor number in both cationic and anionic units, each of which is based on a high dielectric constant lead structure. We designed and synthesized two series of ILs and determined their ionizing-dissociating abilities and activities of lipases soluble in these new ILs. RESULTS: The results showed that the ionizing-dissociating abilities of ILs paralleled the catalytic activity trend of lipases dissolved in the ILs. The activities of lipases soluble in the newly designed ILs were comparable to those in water. CONCLUSIONS: We can conclude that ionizing-dissociating abilities of an IL can be used as a basis for predicting the activity of enzymes soluble in the IL. GENERAL SIGNIFICANCE: Ionization basis for activation of enzymes gives a deeper understanding of the behavior of enzymes in non-aqueous media at a molecular level.

KW - ionization

KW - activation

KW - enzyme

KW - ionic liquid

UR - http://www.sciencedirect.com/science/journal/03044165

U2 - 10.1016/j.bbagen.2016.04.004

DO - 10.1016/j.bbagen.2016.04.004

M3 - Article

VL - 1860

SP - 1404

EP - 1408

JO - BBA - General Subjects

T2 - BBA - General Subjects

JF - BBA - General Subjects

SN - 0304-4165

IS - 7

ER -