title: Fluorescence sensing of adenosine deaminase based on adenosine induced self-assembly of aptamer structures.
abstract: A new approach is proposed for simple detection of adenosine deaminase (ADA) based on adenosine induced self-assembly of two pieces of single-stranded DNA (ssDNA). These ssDNA are two fragments of the aptamer that has a strong affinity for adenosine and are labeled with carboxyfluorescein and black hole quencher-1, respectively. The complementarities of the bases in the two pieces of ssDNA are insufficient to form a stable structure. In the presence of adenosine, however, the ssDNA can be assembled into the intact aptamer tertiary structure, which results in fluorescence quenching of the carboxyfluorescein-labeled aptamer fragment. As a result, the adenosine-ssDNA complex shows a low background signal, which is rather desired for achieving sensitive detection. Reaction of the complex with ADA causes a great fluorescence enhancement by converting adenosine into inosine that has no affinity for the aptamer. This behaviour leads to the development of a simple and sensitive fluorescent method for assaying ADA activity, with a detection limit of 0.05 U mL(-1), which is more sensitive than most of the existing approaches. Furthermore, the applicability of the method has been demonstrated by detecting ADA in mouse serum samples.
authors: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors: Tingting
authors: T
authors: Feng
authors: Huimin
authors: H
authors: Ma
mesh_terms: D000241:Adenosine / Q000737:chemistry; D000243:Adenosine Deaminase / Q000032:analysis / Q000097:blood* / Q000737:chemistry; D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D005452:Fluoresceins / Q000737:chemistry; D057230:Limit of Detection; D051379:Mice; D013050:Spectrometry, Fluorescence
chemical_list: D052157:Aptamers, Nucleotide; D004277:DNA, Single-Stranded; D005452:Fluoresceins; C024098:6-carboxyfluorescein; D000243:Adenosine Deaminase; D000241:Adenosine