Labelled nucleotides

1. A method for determining the sequence of a target single-stranded polynucleotide, comprising monitoring the sequential incorporation of complementary nucleotides,

wherein the nucleotides each have a base that is linked to a detectable label vial a cleavable linker, wherein each of the nucleotides has a ribose or deoxyribose sugar moiety and the ribose or deoxyribose sugar moiety comprises a protecting group attached via the 2′ or 3′ oxygen atom, and

wherein the identity of each nucleotide incorporated is determined by detection of the label linked to the base, and subsequent removal of the label and the protecting group under a single set of conditions.

2. A method according to claim 1 , further comprising the steps of

(a) providing said nucleotides;

and wherein said monitoring comprises

(b) incorporating a nucleotide into the complement of the target single stranded polynucleotide;

(c) detecting the label of the nucleotide of (b), thereby determining the type of nucleotide incorporated;

(d) removing the label of the nucleotide of (b); and

(e) optionally repeating steps (b)-(d) one or more times; thereby determining the sequence of a target single-stranded polynucleotide.

3. A method according to claim 1 ,

wherein each of the nucleotides are brought into contact with the target sequentially,

with removal of non-incorporated nucleotides prior to addition of the next nucleotide, and

wherein detection and removal of the label is carried out either after addition of each nucleotide, or after addition of all four nucleotides.

4. A method according to claim 1 , wherein each of the nucleotides are brought into contact with the target together simultaneously, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label.

5. A method according to claim 1 , comprising a first step and a second step,

wherein in the first step, a first composition comprising two of the four nucleotides is brought into contact with the target, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label, and

wherein in the second step, a second composition comprising the two nucleotides not included in the first composition is brought into contact with the target, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label,

and wherein the first step and the second step are optionally repeated one or more times.

6. A method according to claim 1 , comprising a first step and a second step,

wherein in the first step, a composition comprising one of the four nucleotides is brought into contact with the target, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label, and

wherein in the second step, a second composition comprising the three nucleotides not included in the first composition is brought into contact with the target, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label, and

wherein the first step and the second step are optionally repeated one or more times.

7. A method according to claim 1 , comprising a first step and a second step,

wherein in the first step, a first composition comprising three of the four nucleotides is brought into contact with the target, and non-incorporated nucleotides are removed prior to detection and subsequent to removal of the label, and

wherein in the second step, a composition comprising the nucleotide not included in the first composition is brought into contact with the target, and nonincorporated nucleotides are removed prior to detection and subsequent to removal of the label, and

wherein the first step and the second step are optionally repeated one or more times.

8. A method according to claim 1 , wherein each of the nucleotides has a base that is linked to a detectable label via a cleavable linker, wherein the cleavable linker comprises a protected hydroxyl functionality.

9. A method according to claim 1 , wherein cleavage of the cleavable linker produces a hydroxyl group attached to the base.

10. A method according to claim 1 , wherein cleavage of the cleavable linker produces a hydroxyl group attached to the detectable label.

11. A method according to claim 1 , wherein each of the nucleotides is a deoxyribonucleotide triphosphate.

12. A method according to claim 1 , wherein the detectable label is a fluorophore.

13. A method according to claim 1 , wherein the cleavable linker comprises a moiety cleavable using palladium.

14. A method according to claim 1 , wherein the cleavable linker comprises a cleavable allylic system.

15. A method according to claim 1 , wherein the cleavable linker is photocleavable.

16. A method according to claim 1 , wherein the detectable label and/or cleavable linker is of sufficient size to limit the incorporation of further nucleotides into a nucleic acid template strand.

17. A method according to claim 1 , wherein the target single-stranded polynucleotide is immobilised on a solid support.

18. A method according to claim 17 , wherein the solid support is a bead or microsphere.

19. A method according to claim 17 , wherein the solid support is a glass slide.