Effect of pH on the activity of ice-binding protein from Marinomonas primoryensis

Abstract

The ability of an ice-binding protein (IBP) from Marinomonas primoryensis (MpIBP) to influence ice crystal growth and structure in non-physiological pH environments was investigated in this work. The ability for MpIBP to retain ice interactivity under stressed environmental conditions was determined via (1) a modified splat assay to determine ice recrystallization inhibition (IRI) of polycrystalline ice and (2) nanoliter osmometry to evaluate the ability of MpIBP to dynamically shape the morphology of a single ice crystal. Circular dichroism (CD) was used to relate the IRI and DIS activity of MpIBP to secondary structure. Results illustrate that MpIBP secondary structure was stable between pH 6 -pH 10. It was found that MpIBP did not interact with ice at pH ≤ 4 or pH ≥ 13. At 6 ≤ pH ≥ 12 MpIBP exhibited a reduction in grain size of ice crystals compared to control solutions and demonstrated dynamic ice shaping at 6 ≤ pH ≥ 10. The results substantiate that MpIBP retains some secondary structure and function in non-neutral pH environments, thereby enabling its potential utility in non-physiological materials science and engineering applications.

Constant pH Coarse-Grained Molecular Dynamics with Stochastic Charge Neutralization

“…However, pH and by extension p K a influence a wide range of research areas include graphene oxide adsorption capacity, 1 peptide self- and co-assembly, 2 and protein structure; 3 even extremophile bacterial ice-binding proteins are hindered at slightly below physiological pH (<6). 4 …”

“…However, pH and by extension pK a influence a wide range of research areas include graphene oxide adsorption capacity, 1 peptide self-and co-assembly, 2 and protein structure; 3 even extremophile bacterial ice-binding proteins are hindered at slightly below physiological pH (<6). 4 Herein, we describe a method of performing constant pH molecular dynamics (CpHMD) with dynamic stochastic charge neutralization on the basis of the method developed by Radak et al 5 Modifications have been introduced to enable net charge neutralization as well as for the capture of broad apparent pK a shifts in aggregates of minimal low dielectric constants. In the validation of this methodology as well as the exploration of use cases, three self-assembling systems of increasing complexity and with existing experimentally quantified pK a changes or pH-dependent phase changes were investigated.…”

A Bioinspired Threonine-based Antifreeze Protein Mimic with Potent Ice Recrystallization Inhibition Activity

“…23,24 Previous studies that report on IBPs in pH 13 solution found that the alkaline environment disrupted the proteins ability to prevent ice crystal growth, such as a previous study by the authors that demonstrated an IBP from the Antarctic bacterium Marinomonas primoryensis increased grain size in pH 13 solution. 52 As the ice inhibition activity imparted by pThr and 45 kDa pHPMA is not reliant on secondary structure like IBPs, they offer a distinct advantage at preventing ice growth in non-physiological environments compared to their biological counterparts. A previous study performed by Burkey et al 37 investigated the performance of PVA with a molecular weight of 27 kDa at 1 mg/mL in pH 13 solution and found that the reduction in crystal size was ~80%, further corroborating that synthetics perform better in non-physiological environments than IBPs, offering potential ice inhibition strategies in engineering applications, such as freeze-thaw mitigation in cement and concrete in which the pore solution pH is ≥ 13.…”

A Bioinspired Threonine-based Antifreeze Protein Mimic with Potent Ice Recrystallization Inhibition Activity

“…23,24 Previous studies that report on IBPs in pH 13 solution found that the alkaline environment disrupted the proteins ability to prevent ice crystal growth, such as a previous study by the authors that demonstrated an IBP from the Antarctic bacterium Marinomonas primoryensis increased grain size in pH 13 solution. 52 As the ice inhibition activity imparted by pThr and 45 kDa pHPMA is not reliant on secondary structure like IBPs, they offer a distinct advantage at preventing ice growth in non-physiological environments compared to their biological counterparts. A previous study performed by Burkey et al 37 investigated the performance of PVA with a molecular weight of 27 kDa at 1 mg/mL in pH 13 solution and found that the reduction in crystal size was ~80%, further corroborating that synthetics perform better in non-physiological environments than IBPs, offering potential ice inhibition strategies in engineering applications, such as freeze-thaw mitigation in cement and concrete in which the pore solution pH is ≥ 13.…”