Improving the protein activity and stability under acidic conditions via site-specific conjugation of a pH-responsive polyelectrolyte

Reversible assembly and disassembly of a supramolecular capsule bearing multiple acridine panels occur in water under neutral and acidic conditions, respectively. The pH-responsive capsule encapsulates various hydrophobic compounds in neutral water and subsequently releases them by simple acidification.

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REP-X: An Evolution-guided Strategy for the Rational Design of Cysteine-less Protein Variants

10.1101/797969 ◽

2019 ◽

Author(s):

Kevin Dalton ◽

Tom Lopez ◽

Vijay Pande ◽

Judith Frydman

Keyword(s):

Rational Design ◽

Biochemical Characterization ◽

Cysteine Residue ◽

Rational Approach ◽

Protein Activity ◽

Methanococcus Maripaludis ◽

Site Specific ◽

Protein Variants ◽

Group Ii Chaperonin ◽

Reduced Activity

AbstractSite-specific labeling of proteins is often a prerequisite for biophysical and biochemical characterization. Chemical modification of a unique cysteine residue is among the most facile methods for site-specific labeling of proteins. However, many proteins have multiple reactive cysteines, which must be mutated to other residues to enable labeling of unique positions. This trial-and-error process often results in cysteine-free proteins with reduced activity or stability. Herein we describe a general methodology to rationally engineer cysteine-less proteins. Briefly, natural variation across orthologues is exploited to identify suitable cysteine replacements compatible with protein activity and stability. As a proof-of-concept, we recount the successful engineering of a cysteine-less mutant of the group II chaperonin from methanogenic archaeon Methanococcus maripaludis. A webapp, REP-X (Replacement at Endogenous Positions from eXtant sequences), which enables users to design their own cysteine-less protein variants, will make this rational approach widely available.

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Fullerenol-Capped Porous Silica Nanoparticles for pH-Responsive Drug Delivery

Advances in Materials Science and Engineering ◽

10.1155/2015/567350 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Nikola Ž. Knežević ◽

Sanja Milenković ◽

Danica Jović ◽

Slavica Lazarevic ◽

Jasminka Mrdjanović ◽

...

Keyword(s):

Drug Delivery ◽

Thermogravimetric Analysis ◽

Drug Release ◽

Silica Nanoparticles ◽

Porous Silica ◽

Targeted Treatment ◽

Capping Agent ◽

Ph Responsive ◽

Tumor Tissues ◽

Acidic Conditions

Novel nanocomposite containing fullerenol nanoparticles (FNP) and porous silica nanoparticles (PSNs) was constructed and characterized. The capability of FNP to serve as a pore-capping agent and for entrapping 9-aminoacridine (9-AA) inside the pores of the PSN material was also demonstrated. Nitrogen sorption measurements evidence the successful capping of the silica pores while thermogravimetric analysis of FNP loaded PSN indicates the existence of pore-loaded fullerenol molecules. Higher amount of the drug release was noted by exposing the material to weakly acidic conditions in comparison to physiological pH, which may find application in targeted treatment of weakly acidic tumor tissues.

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pH-Responsive Lipid Nanocapsules: A Promising Strategy for Improved Resistant Melanoma Cell Internalization

Cancers ◽

10.3390/cancers13092028 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2028

Author(s):

Vincent Pautu ◽

Elise Lepeltier ◽

Adélie Mellinger ◽

Jérémie Riou ◽

Antoine Debuigne ◽

...

Keyword(s):

Positive Charge ◽

Cell Entry ◽

Ph Responsive ◽

Lipid Nanocapsules ◽

Anticancer Efficacy ◽

Cell Internalization ◽

Promising Strategy ◽

Acidic Conditions ◽

Melanoma Therapy

Despite significant advances in melanoma therapy, low response rates and multidrug resistance (MDR) have been described, reducing the anticancer efficacy of the administered molecules. Among the causes to explain these resistances, the decreased intratumoral pH is known to potentiate MDR and to reduce the sensitivity to anticancer molecules. Nanomedicines have been widely exploited as the carriers of MDR reversing molecules. Lipid nanocapsules (LNC) are nanoparticles that have already demonstrated their ability to improve cancer treatment. Here, LNC were modified with novel copolymers that combine N-vinylpyrrolidone (NVP) to impart stealth properties and vinyl imidazole (Vim), providing pH-responsive ability to address classical chemoresistance by improving tumor cell entry. These copolymers could be post-inserted at the LNC surface, leading to the property of going from neutral charge under physiological pH to positive charge under acidic conditions. LNC modified with polymer P5 (C18H37-P(NVP21-co-Vim15)) showed in vitro pH-responsive properties characterized by an enhanced cellular uptake under acidic conditions. Moreover, P5 surface modification led to an increased biological effect by protecting the nanocarrier from opsonization by complement activation. These data suggest that pH-sensitive LNC responds to what is expected from a promising nanocarrier to target metastatic melanoma.

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