Jain NK, Jetani HC, Roy I. Nucleic acid aptamers as stabilizers of proteins: the stability of tetanus toxoid.
Pharm Res 2013;
30:1871-82. [PMID:
23568526 DOI:
10.1007/s11095-013-1030-7]
[Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/12/2013] [Indexed: 01/07/2023]
Abstract
PURPOSE
Exposure of tetanus toxoid to moisture leads to its aggregation and reduction of potency. The aim of this work was to use SELEX (systematic evolution of ligands by exponential enrichment) protocol and select aptamers which recognize tetanus toxoid (Mr ~150 kDa) with high affinity.
METHODS
Colyophilized preparations of tetanus toxoid and specific aptamers were encapsulated in PLGA microspheres and sustained release of the antigen was observed up to 55 days using different techniques.
RESULTS
The total protein released was between 40-55% (24-45% residual antigenicity) in the presence of the aptamers as compared to 25% (11% residual antigenicity) for the antigen alone. We show that instead of inhibiting absorption of moisture, the aptamers blocked the protein unfolding upon absorption of moisture, inhibiting the initiation of aggregation. When exposed to accelerated storage conditions, some of the RNA sequences were able to inhibit moisture-induced aggregation in vitro and retain antigenicity of tetanus toxoid.
CONCLUSIONS
Nucleic acid aptamers represent a novel class of protein stabilizers which stabilize the protein by interacting directly with it. This mechanism is unlike that of small molecules which alter the medium properties and hence depend on the stress condition a protein is exposed to.
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