ENZYMATIC ENCODING METHODS FOR EFFICIENT SYNTHESIS OF LARGE LIBRARIES

• US 20090264300A1
• Filed: 12/01/2006
• Published: 10/22/2009
• Est. Priority Date: 12/01/2005
• Status: Active Grant

• Current Assignee: Nuevolution A/S (Amgen Inc.)
• Original Assignee: Nuevolution A/S (Amgen Inc.)
• Inventors: Sams, Christian Klarner, Husemoen, Gitte Nystrup, Slok, Frank Abildgaard, Goldbech, Anne, Dolberg, Johannes, Neve, Sore, Hansen, Anders Holm, Jacobsen, Soren Nyboe, Sorensen, Anders Malling, Kaldor, Ditte Kievsmose, Kronborg, Tine Titilola Akinleminu, Andersen, Anne Lee, Pedersen, Lene, Jensen, Kim Birkebaek, de Leon, Daen, Norregaard-Madsen, Mads, Franch, Thomas, Gouliaev, Alex Haahr, Pedersen, Henrik, Holtmann, Anette, Lundorf, Mikkel Dybro, Felding, Jakob, Godskesen, Michael Anders, Thisted, Thomas, Olsen, Eva Kampmann, Freskgard, Per-Ola, Glad, Sanne Schroder
• Granted Patent: US 9,574,189 B2
• Time in Patent Office: Days
• US Class Current: 506/4
• CPC Class Codes: C12N 15/1068 Template (nucleic acid) mediated chemical library synthesis, e.g. chemical and enzymatical DNA-templated organic molecule synthesis, libraries prepared by non ribosomal polypeptide synthesis [NRPS], DNA/RNA-polymerase mediated polypeptide synthesis
• CPC Class Codes: C12N 15/1089 Design, preparation, screening or analysis of libraries using computer algorithms
• CPC Class Codes: C40B 40/08 Libraries containing RNA or DNA which encodes proteins, e.g. gene libraries
• CPC Class Codes: C40B 50/04 using dynamic combinatorial chemistry techniques
• CPC Class Codes: C40B 50/06 Biochemical methods, e.g. using enzymes or whole viable microorganisms

Abstract

Disclosed is a method for obtaining a bifunctional complex comprising a molecule linked to a single stranded identifier oligonucleotide, wherein a nascent bifunctional complex comprising a chemical reaction site and a priming site for enzymatic addition of a tag is a) reacted at the chemical reaction site with one or more reactants, and b) reacted enzymatically at the priming site with one or more tag(s) identifying the reactant(s).

Claims

1. A method for the synthesis of a bifunctional complex comprising a molecule and a single stranded oligonucleotide identifier attached to the molecule, said method comprising the steps of

i) providing a display oligonucleotide attached to

a) one or more chemical reaction site(s) comprising one or more reactive groups and

b) one or more priming site(s) for enzymatic addition of a tag,

ii) providing a first reactant comprising one or more chemical entities and one or more reactive groups capable of reacting with

c) the chemical reaction site(s) of the display oligonucleotide, and/or

d) one or more reactive groups of at least a first further reactant comprising one or more chemical entities, wherein said first further reactant is provided simultaneously or sequentially in any order with the first reactant,

iii) providing a first oligonucleotide tag capable of hybridising to part of a first oligonucleotide anti-tag, wherein the first oligonucleotide tag identifies the first reactant and, optionally, the further first reactant,

iv) providing a first oligonucleotide anti-tag capable of hybridising to at least part of the first oligonucleotide tag provided in step iii) and to at least part of the display oligonucleotide provided in step i),

v) reacting the first reactant provided in step ii) with c) the one or more chemical reaction site(s) of the display oligonucleotide and/or with d) the one or more reactive groups of the first further reactant comprising one or more chemical entities,

wherein the reaction of complementary reactive groups result in the formation of a covalent bond, and

wherein one or more reactive group reactions of step v) result in the formation of one or more covalent bond(s) between the chemical reaction site(s) of the display oligo and at least one chemical entity of at least one reactant selected from the group consisting of the first reactant and the further first reactant,

vi) hybridising the anti-tag to the display oligonucleotide and to the first oligonucleotide tag,

wherein method steps v) and vi) are simultaneous or sequential in any order,

vii) enzymatically ligating the display oligonucleotide and the first oligonucleotide tag,

viii) providing a second reactant comprising one or more chemical entities and one or more reactive groups capable of reacting with

c) the chemical reaction site(s) of the display oligonucleotide, and/or

d) one or more reactive groups of one or more reactant(s) having reacted in a previous synthesis round, and/or

e) one or more reactive groups of at least a second further reactant comprising one or more chemical entities, wherein said second further reactant is provided simultaneously or sequentially in any order with the second reactant,

ix) providing a second oligonucleotide tag capable of hybridising to part of a second oligonucleotide anti-tag, wherein the second oligonucleotide tag identifies the second reactant and, optionally, the further second reactant,

x) providing a second oligonucleotide anti-tag capable of hybridising to part of the first oligonucleotide tag provided in step iii) and to part of the second oligonucleotide tag provided in step ix),

xi) reacting the second reactant provided in step viii) with c) the chemical reaction site(s) of the display oligonucleotide and/or d) one or more reactive groups of one or more reactant(s) having reacted in a previous synthesis round and/or e) one or more reactive groups of a further second reactant comprising one or more chemical entities,

wherein the reaction of complementary reactive groups result in the formation of a covalent bond, and

wherein one or more reactive group reactions of step xi) result in

f) the formation of one or more covalent bond(s) between the one or more chemical reaction site(s) and at least one chemical entity of at least one reactant selected from the group consisting of the second reactant and the further second reactant, and/or

g) the formation of one or more covalent bond(s) between a reactant having reacted in a previous synthesis round and at least one chemical entity of at least one reactant selected from the group consisting of the second reactant and the further second reactant,

xii) hybridising the anti-tag to the first oligonucleotide tag and the second oligonucleotide tag,

wherein method steps xi) and xii) are simultaneous or sequential in any order.

xiii) enzymatically ligating the first and second oligonucleotide tags in the absence of ligation the first and second anti-tag oligonucleotides, and optionally

xiv) displacing unligated anti-tags from the bifunctional complex comprising a molecule and a single stranded oligonucleotide identifier comprising tags identifying the reactants which participated in the synthesis of the molecule.

2. The method of claim 1, wherein the method of claim 1 is performed in parallel in different reaction compartments, wherein the display oligonucleotide of step i) is provided in each of a plurality of separate reaction compartments and subsequently, wherein, in each of said reaction compartments, the first reactant and optionally also the further first reactant is/are reacted with the one or more chemical reaction site(s), and wherein, in each of said compartments, a first oligonucleotide tag identifying said one or more reactant(s) is added enzymatically to the one or more priming site(s), said reaction(s) of said reactant(s) and said addition(s) of said tag resulting in the formation, in each of said reaction compartments, of different nascent bifunctional complexes.

3. The method of claim 2, wherein said different nascent bifunctional complexes are mixed, and wherein said mixture of different nascent bifunctional complexes is subsequently divided into a plurality of different reaction compartments.

4. The method of claim 3, wherein a different nascent bifunctional complex is provided in each of said plurality of separate reaction compartments and subsequently, in each of said reaction compartments, the second reactant and optionally also the further second reactant is/are reacted with one or more of a chemical reaction site and one or more reactive group(s) of a first reactant and/or further first reactant, and wherein, in each of said compartments, a second oligonucleotide tag identifying said one or more reactant(s) is added enzymatically to the first oligonucleotide tag, said reaction(s) of said reactant(s) and said addition(s) of said tag resulting in the formation, in each of said compartments, of further different nascent bifunctional complexes.

5. The method of claim 4, wherein, in each subsequent round of parallel synthesis, the reactant reaction product of a previous synthesis round reacts with the reactant in a subsequent synthesis round, and wherein a tag added in a previous synthesis round acts as a substrate for the enzyme which adds a tag in a subsequent synthesis round.

13. The method of claim 1, wherein the identifier oligonucleotide is amplifiable.

14. The method of claim 1, wherein the display oligonucleotide has a length of from about 3 consecutive nucleotides to about 25 consecutive nucleotides.

16. The method of claim 14, wherein tag(s) have from about 3 consecutive nucleotides to about 25 consecutive nucleotides.

18. The method of claim 14, wherein anti-tag(s) have from about 3 consecutive nucleotides to about 25 consecutive nucleotides.

20. The method of claim 14, wherein single-stranded over-hangs resulting from hybridisation of tags and anti-tags have a length of from about 3 consecutive nucleotides to about 25 consecutive nucleotides.

22. The method of claim 1, wherein the identifier oligonucleotide resulting from tag ligation(s) has a length of from 6 to about 200 consecutive nucleotides.

24. The method of claim 1, wherein the identifier oligonucleotide comprises a string of consecutive nucleotides comprising from 2 to 10 tags.

38. The method of claim 1, wherein end-positioned nucleotides of anti-tags comprises no reactive group(s) capable of being linked by an enzyme comprising ligase activity.

39. The method of claim 1, wherein the one or more priming site(s) of the display oligonucleotide comprises a 3′

-OH or 5′

-phosphate group, or a functional derivative of such a group, capable of being linked by an enzyme comprising ligase activity.

40. The method of claim 1, wherein molecule decoding or reactant identification is performed by sequencing all or some of the nucleotides of each tag of the identifier oligonucleotide.

43. The method of claim 1, wherein the one or more chemical reaction site(s) of the display oligonucleotide each comprising one or more reactive groups react with one or more reactants each comprising one or more reactive groups, wherein the chemical reaction sites can the same or different chemical reaction sites, wherein the reactive groups can be the same or different reactive groups, and wherein the reactants can be the same or different reactants.

59. The method of claim 1, wherein the reactive groups involved in the synthesis of a molecule are selected from the group consisting of carboxylic acids, alcohols, thiols, aldehydes, ketones, amides, imides, amines, azo, diazo, azido, hydrazines, carbamates, esters, thioesters, cyanides, ethers, isocyanates, isothiocyanates, sulfides, nitrites, nitrites, nitrates, nitro, peroxides, phosphates, thiophosphates, sulfides, epoxides, anhydrides, halides, acid halides, organometallics, nitrides, phosphides, carbides, and suicides.

60. The method of claim 1, wherein the reaction of the chemical reaction site and a reactant, or the reaction of different reactants, results in the formation of at least one bond selected from the group consisting of peptide bonds, sulfonamide bonds, ester bonds, saccharide bonds, carbamate bonds, carbonate bonds, urea bonds, phosphonate bonds, urethane bonds, azatide bonds, peptoid bonds, ether bonds, ethoxy bonds, thioether bonds, single carbon bonds, double carbon bonds, triple carbon bonds, disulfide bonds, sulfide bonds, phosphodiester bonds, oxime bonds, imine bonds, imide bonds, and any combination thereof.

61. The method of claim 1, wherein the reaction of the chemical reaction site and a reactant, or the reaction of different reactants, results in the formation of at least one bond selected from the group consisting of —

NHN(R)CO—

;

—

NHB(R)CO—

;

—

NHC(RR′

)CO—

;

—

NHC(═

CHR)CO—

;

—

NHC₆H₄CO—

;

—

NHCH₂CHRCO—

;

—

NHCHRCH₂CO—

;

—

COCH₂—

;

—

COS—

;

—

CONR—

;

—

COO—

;

—

CSNH—

;

—

CH₂ NH—

;

—

CH₂CH₂—

;

—

CH₂S—

;

—

CH₂SO—

;

—

CH₂SO₂—

;

—

CH(CH₃)S—

;

—

CH═

CH—

;

—

NHCO—

;

—

NHCONH—

;

—

CONHO—

;

—

C(═

CH₂)CH₂—

;

—

PO₂⁻

—

NH—

;

—

PO₂⁻

CH₂—

;

—

PO₂⁻

CH₂N⁺;

—

SO₂NH⁻

—

; and

lactams.

62. The method of claim 1, wherein complementary reactive groups of the chemical reaction site and/or the reactive group(s) of one or more reactants reacting with each other and/or with the chemical reaction site are selected from the group consisting of

a) activated carboxyl groups, reactive sulfonyl groups and reactive phosphonyl groups, or a combination thereof, and complementary primary or secondary amino groups;

wherein the complementary reactive groups react under suitable conditions to form amide, sulfonamide and/or phosphonamidate bonds;

b) epoxide groups and complementary primary and/or secondary amino groups;

wherein a reactant comprising one or more epoxide reactive group(s) reacts with one or more amine-group(s) of a complementary reactant under suitable conditions to form one or more carbon-nitrogen bond(s);

c) aziridine groups and complementary primary or secondary amino groups;

wherein under suitable conditions, a reactant comprising one or more aziridine-group(s) reacts with one or more amine-group(s) of a complementary reactant to form one or more carbon-nitrogen bond(s);

d) isocyanate groups and complementary primary or secondary amino groups, wherein a reactant comprising one or more isocyanate-group(s) reacts with one or more amino-group(s) of a complementary reactant under suitable conditions to form one or more carbon-nitrogen bond(s);

e) isocyanate groups and complementary hydroxyl groups;

wherein a reactant comprising one or more isocyanate-group(s) reacts with a complementary reactant comprising one or more hydroxyl-groups under suitable conditions to form one or more carbon-oxygen bond(s);

i) amino groups and complementary carbonyl groups;

wherein a reactant comprising one or more amino groups reacts with a complementary reactant comprising one or more carbonyl-group(s);

wherein the amines react with such groups via reductive amination to form a carbon-nitrogen bond;

g) phosphorous ylide groups and complementary aldehyde and/or ketone groups;

wherein a reactant comprising a phosphorus-ylide-group reacts with an aldehyde and/or a ketone-group of a complementary reactant under suitable conditions to form eg. a carbon-carbon double bond;

h) complementary reactive groups reacting via cycloaddition to form a cyclic structure;

such as the reaction of alkynes and organic azides, which react under suitable conditions to form a triazole ring structure;

i) alkyl halide groups and one or more nucleophile group(s), such as amino groups, hydroxyl groups and carboxyl group;

wherein such groups react under suitable conditions to form a carbon-nitrogen bond (alkyl halide plus amine) or carbon oxygen bond (alkyl halide plus hydroxyl or carboxyl group); and

j) halogenated heteroaromatic groups and one or more nucleophile group(s), wherein the reactants react under suitable conditions via aromatic nucleophilic substitution;

wherein halogenated heteroaromatic groups are optionally selected from chlorinated pyrimidines, triazines and purines, which react with nucleophiles, under mild conditions in aqueous solution.

89. The method of claim 1, wherein the chemical reaction site comprises a scaffold comprising one or more reactive groups.

90. The method of claim 89, wherein the scaffold reactive groups are selected from the group consisting of carboxylic acids, alcohols, thiols, aldehydes, ketones, amides, imides, amines, azo, diazo, azido, hydrazines, carbamates, esters, thioesters, cyanides, ethers, isocyanates, isothiocyanates, sulfides, nitriles, nitrites, nitrates, nitro, peroxides, phosphates, thiophosphates, sulfides, epoxides, anhydrides, halides, acid halides, organometallics, nitrides, phosphides, carbides, and silicides.

91. The method of claim 89, wherein scaffold comprises a scaffold moiety selected from the group consisting of quinazoline, tricyclic quinazoline, purine, pyrimidine, phenylamine-pyrimidine, phthalazine, benzylidene malononitrile, amino acid, tertiary amine, peptide, lactam, sultam, lactone, pyrrole, pyrrolidine, pyrrolinone, oxazole, isoxazole, oxazoline, isoxazoline, oxazolinone, isoxazolinone, thiazole, thiozolidinone, hydantoin, pyrazole, pyrazoline, pyrazolone, imidazole, imidazolidine, imidazolone, triazole, thiadiazole, oxadiazole, furan, benzoffuran, isobenzofuran, dihydrobenzofuran, dihydroisobenzofuran, indole, indoline, benzoxazole, oxindole, indolizine, benzimidazole, benzimidazolone, pyridine, piperidine, piperidinone, pyrimidinone, piperazine, piperazinone, diketopiperazine, metathiazanone, morpholine, thiomorpholine, phenol, dihydropyran, quinoline, isoquinoline, quinolinone, isoquinolinone, quinolone, quinazolinone, quinoxalinone, benzopiperazinone, benzodiazepine, quinazolinedione, benzazepine, azepine, tropane, and coumarine.

92. The method of claim 1, wherein the molecule is a branched or cyclical molecule.

93. The method of claim 92, wherein the molecule is cyclical and comprises a ring system selected from a single ring system and a fused ring system.

94. The method of claim 93, wherein one or more heteroatoms are present in either the single ring system or in the fused ring system.

95. The method of claim 93, wherein the single ring system is not directly bonded at more than one ring atom to another closed ring, and wherein the fused ring system is directly bonded at more than one ring atom to another closed ring.

112. The method of claim 1, wherein the molecule is synthesised by one or more reactions selected from the group consisting of amine acylation, reductive alkylation, aromatic reduction, aromatic acylation, aromatic cyclization, aryl-aryl coupling, [3+2]cycloaddition, Mitsunobu reaction, nucleophilic aromatic substitution, sulfonylation, aromatic halide displacement, Michael addition, Wittig reaction, Knoevenagel condensation, reductive amination, Heck reaction, Stille reaction, Suzuki reaction, Aldol condensation, Claisen condensation, amino acid coupling, amide bond formation, acetal formation, Diels-Alder reaction, [2+2]cycloaddition, enamine formation, esterification, Friedel Crafts reaction, glycosylation, Grignard reaction, Horner-Emmons reaction, hydrolysis, imine formation, metathesis reaction, nucleophilic substitution, oxidation, Pictet-Spengler reaction, Sonogashira reaction, thiazolidine formation, thiourea formation and urea formation.

113. The method of claim 1, wherein the one or more chemical reaction site(s) are covalently linked to the one or more priming site(s).

6-12. -12. (canceled)

15. (canceled)

17. (canceled)

19. (canceled)

21. (canceled)

23. (canceled)

25-37. -37. (canceled)

41-42. -42. (canceled)

44-58. -58. (canceled)

63-88. -88. (canceled)

96-111. -111. (canceled)

114-115. -115. (canceled)

116. A method for the synthesis of a plurality of different bifunctional complexes, said method comprising the steps of

i) providing a plurality of display oligonucleotides each attached to

a) one or more chemical reaction site(s) comprising one or more reactive groups and

b) one or more priming site(s) for enzymatic addition of a tag,

ii) providing a plurality of first reactants each comprising one or more chemical entities and one or more reactive groups, each first reactant being capable of reacting with

c) the one or more chemical reaction site(s) of the display oligonucleotide, and/or

d) one or more reactive groups of a first further reactant comprising one or more chemical entities, wherein said first further reactant is provided simultaneously or sequentially in any order with the first reactant,

iii) providing a plurality of first oligonucleotide tags each capable of hybridising to part of a first oligonucleotide anti-tag, wherein each first oligonucleotide tag identifies a first reactant and, optionally, a further first reactant,

iv) providing a plurality of first oligonucleotide anti-tags each capable of hybridising to at least part of a first oligonucleotide tag provided in step iii) and to at least part of a display oligonucleotide provided in step i),

v) reacting each of the first reactants provided in step ii) with c) the one or more chemical reaction site(s) of the display oligonucleotides and/or with d) the one or more reactive groups of a first further reactant comprising one or more chemical entities,

wherein the reaction of complementary reactive groups result in the formation of a covalent bond, and

wherein one or more reactive group reactions of step v) result in the formation of one or more covalent bond(s) between the one or more chemical reaction site(s) of the display oligonucleotides and at least one chemical entity of at least one reactant selected from the group consisting of a first reactant and a further first reactant,

vi) hybridising anti-tags to display oligonucleotides and to first oligonucleotide tags,

wherein method steps v) and vi) are simultaneous or sequential in any order,

vii) enzymatically ligating display oligonucleotides and first oligonucleotide tags,

viii) dividing the plurality of nascent bifunctional complexes obtained in step vii) into a plurality of different compartments,

ix) providing in each different compartment a plurality of different second reactants each comprising one or more chemical entities and one or more reactive groups capable of reacting with

c) the one or more chemical reaction site(s) of each of the display oligonucleotides, and/or

d) one or more reactive groups of one or more reactant(s) having reacted in a previous synthesis round, and/or

e) one or more reactive groups of a second further reactant comprising one or more chemical entities, wherein said second further reactants are provided simultaneously or sequentially in any order with the second reactants,

x) providing in each different compartment a plurality of second oligonucleotide tags each capable of hybridising to part of a second oligonucleotide anti-tag, wherein different second oligonucleotide tags are provided in each different compartment, and wherein each different second oligonucleotide identifies a different second reactant and, optionally, a further second reactant which may be the same or a different further second reactant in each different compartment,

xi) providing in each different compartment a plurality of second oligonucleotide anti-tags capable of hybridising to part of a first oligonucleotide tag provided in step iii) and to part of a second oligonucleotide tag provided in step x),

xii) reacting in each different compartment each of the different second reactants provided in step ix) with c) the one or more chemical reaction site(s) of a display oligonucleotide and/or d) one or more reactive groups of one or more reactant(s) having reacted in a previous synthesis round and/or e) one or more reactive groups of a further second reactant comprising one or more chemical entities,

wherein said one or more reactions result in the formation of different bifunctional complexes in each different compartment,

wherein the reaction of complementary reactive groups result in the formation of a covalent bond, and

wherein one or more reactive group reactions of step xii) result in

f) the formation of one or more covalent bond(s) between the one or more chemical reaction site(s) and at least one chemical entity of at least one reactant selected from the group consisting of second reactants and further second reactants, and/or

g) the formation of one or more covalent bond(s) between a reactant having reacted in a previous synthesis round and at least one chemical entity of at least one reactant selected from the group consisting of second reactants and further second reactants,

xiii) hybridising anti-tags to first oligonucleotide tags and second oligonucleotide tags in each different compartment,

wherein method steps xii) and xiii) are simultaneous or sequential in any order,

xiv) enzymatically ligating in each different compartment first and second oligonucleotide tags in the absence of ligation first and second anti-tag oligonucleotides, and optionally

xv) displacing in each compartment unligated anti-tags from bifunctional complexes comprising a molecule and a single stranded oligonucleotide identifier comprising tags identifying the reactants which participated in the synthesis of the molecule.

117. The method of claim 116 comprising the further step of mixing bifunctional complexes from each different reaction compartment.

118. The method of claim 117, wherein, in any round subsequent to the first round, the end product of the preceding round of reaction is used as the nascent bifunctional complex for obtaining a library of different bifunctional complexes.

119. The method of claim 116, wherein steps viii) to xiv) are repeated once or more than once using different reactants and tags identifying said different reactants.

124. A method for identifying a molecule, said method comprising the steps of subjecting the library produced by the method of claim 116 to assaying conditions resulting in the partitioning of some, but not all molecules, from the remainder of the library, and identifying the molecule(s) by decoding the identifier oligonucleotide of the bifunctional complex.

125. The method of claim 124, wherein the library is contacted with a target and wherein bifunctional complexes having an affinity for the target are partitioned form the remainder of the library.

130. The method of claim 125, wherein the identifier oligonucleotide of the one or more partitioned bifunctional complexes, optionally attached to a molecule, and further optionally provided with one or more chemical reaction sites, is subjected to a method for synthesizing a plurality of molecules, said method comprising the steps of:

(a) forming a first group of subsets of identifier oligonucleotides comprising a plurality of nucleic acid tags, where the identifier oligonucleotides in each subset each has a selected one of a plurality of different first hybridization sequences, a mixture of different second hybridization sequences, and one or more chemical reaction site(s),

(b) reacting the chemical reaction sites in each of the subsets formed in (a) with a selected reagent, thereby forming a reagent-specific molecule intermediate on the associated sequence in each subset,

(c) forming a second group of subsets of the reacted identifier oligonucleotides comprising a plurality of nucleic acid tags, where the identifier oligonucleotides in each subset each have a selected one of a plurality of different second hybridization sequences, and a mixture of different first hybridization sequences; and

(d) reacting the molecule intermediates in the sequences in each of the subsets formed in (c) with a selected reagent.

131. The method of claim 130, wherein each of said forming steps includes hybridizing the identifier oligonucleotides comprising a plurality of nucleic acid tags within a given subset with a plurality of solid phase reagents each having a surface bound oligonucleotide or oligonucleotide analog capable of forming base-specific duplexes with one of the hybridizing sequences in the given subset to bind each nucleic acid tag to one of the reagents.

133. The method of claim 130, for use in forming a plurality of small molecules with different chemical sequences, wherein each of said reacting steps includes adding a selected chemical substituent to each of the subsets of identifier oligonucleotides comprising a plurality of nucleic acid tags under conditions effective to add that substituent to the chemical reaction site or last-added substituent carried thereon.

120-123. -123. (canceled)

126-129. -129. (canceled)

132. (canceled)

134-139. -139. (canceled)

140. A bifunctional complex comprising a molecule and a single stranded identifier oligonucleotide identifying the molecule, wherein the single stranded identifier comprises a plurality of covalently linked tags which are at least partly hybridised to one or more corresponding anti-tag(s), wherein the anti-tags are not covalently linked to each other.

161. A library of different bifunctional complexes according to claim 140.

141-160. -160. (canceled)