Patent ID: 6361945
Filing Date: 2002-03-26
Classification: C12Q

Abstract:
A method for determining the presence of a target nucleic acid sequence in a sample which may contain non-target nucleic acids, said method comprising the steps of:a) contacting said sample with a molecular torch comprising: a target binding domain comprising nucleotide base recognition groups; a target closing domain comprising nucleotide base recognition groups, wherein said target binding domain is biased toward said target sequence, such that said target binding domain forms a more stable hybrid with said target sequence than with said target closing domain under the same assay conditions, and wherein said molecular torch does not hybridize to said target sequence when said target binding domain is hybridized to said target closing domain; and a joining region which joins said target binding domain and said target closing domain, wherein said joining region is selected from the group consisting of: one or more non-nucleotide linkers; first and second polynucleotides, or derivatives thereof, said first and second polynucleotides, or derivatives thereof, being substantially complementary to each another; and a combination of said one or more non-nucleotide linkers and said first and second polynucleotides or derivatives thereof, wherein said joining region facilitates the formation of a target binding domain:target closing domain hybrid in the absence of said target sequence; b) exposing a reaction mixture comprising said sample and said molecular torch to denaturing conditions, such that said target binding domain and said target closing domain do not form a stable target binding domain:target closing domain hybrid; c) exposing said reaction mixture to hybridization conditions, such that a target binding domain:target closing domain hybrid is formed in the absence of said target sequence and a target binding domain:target sequence hybrid is formed in the presence of said target sequence, wherein said target binding domain:target sequence hybrid is more stable than said target binding domain:target closing domain hybrid under said hybridization conditions; and d) determining whether a target binding domain:target sequence hybrid is present in said sample as an indication of the presence or absence of said target sequence in said sample.