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Int J Mol Sci. 2017 Jul 19;18(7). pii: E1557. doi: 10.3390/ijms18071557.

Colorful Packages: Encapsulation of Fluorescent Proteins in Complex Coacervate Core Micelles.

Author information

1
Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. antsje.nolles@wur.nl.
2
Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. antsje.nolles@wur.nl.
3
Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. adrie.westphal@wur.nl.
4
MicroSpectroscopy Centre Wageningen, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. adrie.westphal@wur.nl.
5
Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. mieke.kleijn@wur.nl.
6
Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. willem.vanberkel@wur.nl.
7
Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. janwillem.borst@wur.nl.
8
MicroSpectroscopy Centre Wageningen, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands. janwillem.borst@wur.nl.

Abstract

Encapsulation of proteins can be beneficial for food and biomedical applications. To study their biophysical properties in complex coacervate core micelles (C3Ms), we previously encapsulated enhanced green fluorescent protein (EGFP) and its monomeric variant, mEGFP, with the cationic-neutral diblock copolymer poly(2-methyl-vinyl-pyridinium)n-b-poly(ethylene-oxide)m (P2MVPn-b-PEOm) as enveloping material. C3Ms with high packaging densities of fluorescent proteins (FPs) were obtained, resulting in a restricted orientational freedom of the protein molecules, influencing their structural and spectral properties. To address the generality of this behavior, we encapsulated seven FPs with P2MVP41-b-PEO205 and P2MVP128-b-PEO477. Dynamic light scattering and fluorescence correlation spectroscopy showed lower encapsulation efficiencies for members of the Anthozoa class (anFPs) than for Hydrozoa FPs derived from Aequorea victoria (avFPs). Far-UV CD spectra of the free FPs showed remarkable differences between avFPs and anFPs, caused by rounder barrel structures for avFPs and more elliptic ones for anFPs. These structural differences, along with the differences in charge distribution, might explain the variations in encapsulation efficiency between avFPs and anFPs. Furthermore, the avFPs remain monomeric in C3Ms with minor spectral and structural changes. In contrast, the encapsulation of anFPs gives rise to decreased quantum yields (monomeric Kusabira Orange 2 (mKO2) and Tag red fluorescent protein (TagRFP)) or to a pKa shift of the chromophore (FP variant mCherry).

KEYWORDS:

Anthozoa; Hydrozoa; chromophore; circular dichroism; diblock copolymer; dynamic light scattering; fluorescence correlation spectroscopy; polyelectrolyte; protein structure; steady-state fluorescence

PMID:
28753915
PMCID:
PMC5536045
DOI:
10.3390/ijms18071557
[Indexed for MEDLINE]
Free PMC Article

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