Experimental and Theoretical Determination of the pH inside the Confinement of a Virus‐Like Particle

Abstract

In biology, a variety of highly ordered nanometer-size protein cages is found. Such structures find increasing application in, for example, vaccination, drug delivery, and catalysis. Understanding the physiochemical properties, particularly inside the confinement of a protein cage, helps to predict the behavior and properties of new materials based on such particles. Here, the relation between the bulk solution pH and the local pH inside a model protein cage, based on virus-like particles (VLPs) built from the coat proteins of the cowpea chlorotic mottle virus, is investigated. The pH is a crucial parameter in a variety of processes and is potentially significantly influenced by the high concentration of charges residing on the interior of the VLPs. The data show a systematic more acidic pH of 0.5 unit inside the VLP compared to that of the bulk solution for pH values above pH 6, which is explained using a theoretical model based on a Donnan equilibrium. The model agrees with the experimental data over almost two orders of magnitude, while below pH 6 the experimental data point to a buffering capacity of the VLP. These results are a first step in a better understanding of the physiochemical conditions inside a protein cage.

Hollow polymer dots: nature-mimicking architecture for efficient photocatalytic hydrogen evolution reaction

“…Interestingly, a similar phenomenon was found for the nanosized viral protein cage in a certain pH range, which contains pores on the protein shell and allows ions to freely diffusing in and out. 47 By shiing the Pdot-HTPS pH response, it can be noted that it follows the same trend as free probes (see empty blue square in Fig. 2a).…”

“…45,46 HTPS has a highly sensitive pH-dependent absorption shi, allowing ratiometric measurements by taking a ratio of uorescence intensity at emission of l ¼ 515 nm with excitation at l ¼ 455 nm and l ¼ 402 nm. 47 Moreover, HTPS does not permeate through membranes, 43 which results in stable Pdots-HTPS hybrid nanoparticles (NPs) suitable for analysis. Encapsulation of HTPS inside the Pdots was performed by a method similar to the preparation of Pdots.…”

Virus‐Based Nanoreactors with GALT Activity for Classic Galactosemia Therapy

“…The GALT confinement in the BMV capsid is higher that these obtained in P22 VLPs containing cytochrome P450 that was 3.14 mM [63] and higher than the 1 mM obtained in a lipase encapsulated in CCMV capsids [67] . In addition, it has been previously reported that local pH inside CCMV (which shares some sequence identity to BMV) is 0.5 unit more acidic compared to the bulk pH [68] . This acidic difference could reduce the GALT activity inside BMV [69]…”

“…[67] In addition, it has been previously reported that local pH inside CCMV (which shares some sequence identity to BMV) is 0.5 unit more acidic compared to the bulk pH. [68] This acidic difference could reduce the GALT activity inside BMV. [69]…”

Elucidating the Thermodynamic Driving Forces of Polyanion-Templated Virus-like Particle Assembly

“…Moreover, reducing the mobility of ionic species in the samples possibly also reduces the systems entropy. 46…”