Modified proteins and methods of making and using same
First Claim
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1. A system for nucleic acid sequencing, comprising:
- (a) a field effect transistor (FET); and
(b) a modified Bst DNA polymerase comprising three or more amino acid substitutions selected from the group consisting of H46R, H273R, H281R, E446Q, H473R, H528R, H572R and Y477F, the numbering of amino acid residues being in accordance with that of SEQ ID NO. 1, wherein the modified polymerase has reduced buffering capacity compared to wild type Bst DNA polymerase, is configured to catalyze nucleotide polymerization, and comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO. 1; and
wherein the FET comprises an ion sensitive FET (ISFET) configured to detect the release of hydrogen ions as a chemical byproduct of nucleotide incorporation catalyzed by the modified polymerase.
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Abstract
Methods, compositions, systems, apparatuses and kits comprising modified proteins, particularly modified nucleic acid-binding proteins with altered buffering properties are provided. For example, in some embodiments, methods of forming modified proteins including one or more amino acid modifications to achieve desired pKa values are described. Furthermore, the invention provides methods for using such modified proteins in ion-producing reactions, such as ion-based nucleic acid sequencing reactions.
14 Citations
16 Claims
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1. A system for nucleic acid sequencing, comprising:
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(a) a field effect transistor (FET); and (b) a modified Bst DNA polymerase comprising three or more amino acid substitutions selected from the group consisting of H46R, H273R, H281R, E446Q, H473R, H528R, H572R and Y477F, the numbering of amino acid residues being in accordance with that of SEQ ID NO. 1, wherein the modified polymerase has reduced buffering capacity compared to wild type Bst DNA polymerase, is configured to catalyze nucleotide polymerization, and comprises an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO. 1; and wherein the FET comprises an ion sensitive FET (ISFET) configured to detect the release of hydrogen ions as a chemical byproduct of nucleotide incorporation catalyzed by the modified polymerase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification