an oxidized electron donor

a reduced electron donor

a deaminated amino group acceptor

an aminated amino group acceptor

Charged-LEU-tRNAs

LEU-tRNAs

a 2-oxo acid

an amino acid

an acyl-CoA

a carboxylate

an oxidized ferredoxin [iron-sulfur] cluster

a reduced ferredoxin [iron-sulfur] cluster

NAD(P)H

NAD(P)+

an L-tyrosyl-[tRNAtyr]

a tRNAtyr

(2Z,4Z)-2-hydroxy-5-carboxymuconate-6-semialdehyde

4α,14α-dimethyl-porifersta-8,25(27)-dienol

2-amino-4,5-dihydroxy-6-oxo-7-(phosphooxy)heptanoate

4-methylcyclohex-1,5-diene-1-carbonyl-CoA

isoshowacene

2-hydroxyhexadecanal

16-sinapoyloxypalmitate

3-methylquinolin-2-ol

(22R)-hydroxycholesterol

N-(2-methylpropyl)hydroxylamine

chloroeremomycin

3-hydroxy-3-methylbutanoate

2',3',4'-O-methyl-rhamnosyl tetracyclic spinosyn pseudoaglycone

2',3'-O-methyl-rhamnosyl tetracyclic spinosyn pseudoaglycone

2'-O-methyl-rhamnosyl tetracyclic spinosyn pseudoaglycone

rhamnosyl tetracyclic spinosyn pseudoaglycone

rhamnosyl tricyclic spinosyn pseudoaglycone

spinosyn tricyclic macrolactone

11-dehydro-15-oxo spinosyn macrolactone

15-oxo spinosyn macrolactone

spinosyn macrolactone

diethylamine N-oxide

triethylamine N-oxide

UDP-2-acetamido-2-deoxy-α-D-ribo-hex-3-uluronate

nitroxyl

trans,octacis-decaprenylphospho-β-D-arabinofuranose

1,3-dihydro-2H-imidazol-2-one

2-phenylethyl β-D-glucopyranoside

formyl hopane

ribosyl hopane

adenosyl hopane

(2Z)-2-hydroxypenta-2,4-dienoate

(2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate

(2Z)-2,4-dihydroxypent-2-enoate

(2E,7Z,10Z,13Z,16Z,19Z)-docosahexaenoyl-CoA

(3R,5Z,8Z,11Z,14Z,17Z)-3-hydroxydocosapentaenoyl-CoA

(5Z,8Z,11Z,14Z,17Z)-3-oxodocosapentaenoyl-CoA

(+)-3'-hydroxylarreatricin

(+)-larreatricin

2-trans,4-trans-xanthoxin

bisorganyltrisulfane

(2S,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran

(2S,4S)-2-methyl-2,4-dihydroxydihydrofuran-3-one

1,2-dihydro-β-NADP

ammonia

(2R,4S)-2-methyl-2,4-dihydroxydihydrofuran-3-one

(2R,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran

N-succinyl-L,L-2,6-diaminopimelate

quinolinate

urea

presqualene diphosphate

glutathione disulfide

N-(5-phosphoribosyl)-anthranilate

(R)-pantothenate

(R)-4'-phosphopantothenate

(R)-5-phosphomevalonate

(R)-mevalonate diphosphate

12-methyltetradecanoate

glucosyl-4,4'-diaponeurosporenoate

4,5-dihydroxyphthalate

15-cis-4,4'-diapophytoene

D-gluconate 6-phosphate

(R)-mevalonate

L-histidinol phosphate

histidinol

ethyl acetate

isochorismate

(2S,3S)-2,3-dihydroxy-2,3-dihydrobenzoate

2-dehydro-3-deoxy-D-gluconate

2-dehydro-3-deoxy-D-gluconate 6-phosphate

luteolin 7-O-[β-D-glucosyluronate-(1,2)-β-D-glucosiduronate]-4'-O-β-D-glucosiduronate

luteolin 7-O-β-D-diglucuronide

luteolin 7-O-β-D-glucuronide

2-dehydropantoate

N5-(L-1-carboxyethyl)-L-ornithine

shikimate

3-dehydroshikimate

3-deoxy-D-arabino-heptulosonate 7-phosphate

3-dehydroquinate

shikimate 3-phosphate

5-enolpyruvoyl-shikimate 3-phosphate

prephenate

4-hydroxy-2-nonenal

2-hydroxyformononetin

(3R)-sophorol

2'-hydroxypseudobaptigenin

(S)-3-methyl-2-oxopentanoate

4-methyl-2-oxopentanoate

1,4-dihydroxy-2-naphthoate

O-acetyl-L-serine

2-C-methyl-D-erythritol-2,4-cyclodiphosphate

2-C-methyl-D-erythritol 4-phosphate

(3R,5S)-3-hydroxy-1-pyrroline-5-carboxylate

2-methyl-1,4-benzoquinone

methyl-1,4-benzoquinol

(2Z,4E)-2-hydroxyhexa-2,4-dienedioate

β-D-ribosylnicotinate

1-deoxy-L-glycero-tetrulose 4-phosphate

5-amino-6-(D-ribitylamino)uracil

methylsalicylate

salicyl alcohol

3-phosphooxypyruvate

N-acetyl-D-galactosamine 6-phosphate

D-galactosamine-6-phosphate

α-D-glucosamine 1-phosphate

(S)-2,3,4,5-tetrahydrodipicolinate

N-succinyl-2-amino-6-ketopimelate

chloroacetaldehyde

(lipoyl)adenylate

thiamine triphosphate

S-ribosyl-L-homocysteine

autoinducer 2

selenophosphate

4-amino-4-deoxychorismate

2-(α-hydroxyethyl)thiamine diphosphate

3-methyl-2-oxobutanoate

4'-phosphopantetheine

thiamine diphosphate

propanoyl phosphate

glycolate

L-canavanine

DNA without lesion

2-keto-D-gluconate

2,5-didehydro-D-gluconate

N-acetyl-β-D-glucosamine-1,6-anhydro-N-acetyl-β-D-muramate

N^β-acetylstreptothricin F

(S)-dihydroorotate

carboxyphosphate

orotidine 5'-phosphate

carbonic acid

prenyl diphosphate

ethanolamine

1,6-anhydro-N-acetyl-β-muramate

N-acetyl-D-muramate 6-phosphate

hydrogen peroxide

glycerone phosphate

3-[(3aS,4S,7aS)-7a-methyl-1,5-dioxo-octahydro-1H-inden-4-yl]propanoate

3-[(3aS,4S,7aS)-7a-methyl-1,5-dioxo-octahydro-1H-inden-4-yl]propanoyl-CoA

5'-phosphoribosyl-4-(N-succinocarboxamide)-5-aminoimidazole

5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate

5-amino-1-(5-phospho-β-D-ribosyl)imidazole

xanthine

CDP-glycerol

ManNAc-GlcNAc-PP-undecaprenol

S-formylglutathione

5-methylcytosine

dihydroxyacetone

4-amino-2-methyl-5-(diphosphooxymethyl)pyrimidine

thiamine phosphate

CO₂

γ-L-glutamyl 5-phosphate

carbamoyl phosphate

N-acetyl-L-glutamate 5-semialdehyde

N-acetylglutamyl-phosphate

β-nicotinate D-ribonucleotide

nicotinate adenine dinucleotide

acetyl phosphate

oxaloacetate

isopentenyl diphosphate

L-arginino-succinate

O-ureido-L-homoserine

canavaninosuccinate

(S)-4-amino-5-oxopentanoate

5-aminolevulinate

acrylamide

acrylate

propionamide

4-guanidinobutyramide

4-guanidinobutanoate

(indol-3-yl)acetamide

phosphoenolpyruvate

H₂O

(glutathion-S-yl)-4-hydroxy-2-nonenal

DNA with lesion

L-homocysteine

ethylphosphate

hydrogen cyanide

adenosylcobalamin

cob(I)alamin

cob(I)yrinate a,c-diamide

adenosyl-cob(III)yrinate a,c-diamide

cob(I)inamide

adenosylcobinamide

protoporphyrinogen IX

protoporphyrin IX

hydrogen sulfide

oxygen

2-iminosuccinate

2-iminobutanoate

2-iminopropanoate

2-chloroacetate

sn-glycerol 3-phosphate

3-phospho-D-glyceroyl-phosphate

2-phospho-D-glycerate

3-phospho-D-glycerate

α-D-glucosamine 6-phosphate

N-acetyl-D-mannosamine 6-phosphate

3-(all-trans-octaprenyl)benzene-1,2-diol

2-octaprenylphenol

2-methoxy-6-(all-trans-octaprenyl)phenol

5'-deoxy-5'-fluoroadenosine

5-fluoro-5-deoxy-D-ribose 1-phosphate

5'-chloro-5'-deoxyadenosine

5-chloro-5-deoxyribose 1-phosphate

1-chloro-2,4-dinitrobenzene

2,4-dinitrophenyl-S-glutathione

FAD

FADH₂

FMNH₂

FMN

(S)-NADHX

(R)-NADHX

ubiquinol-8

demethylmenaquinol-8

3-demethylubiquinol-8

NADPH

NADH

NADP⁺

NAD⁺

hydroxyl radical

superoxide

(2E,6E)-farnesyl diphosphate

pristanate

Fe³⁺

H⁺

ammonium

Fe²⁺

Zn²⁺

hydrogensulfite

OH^-

thiosulfate

sulfite

selenide

hydrogencarbonate

phosphate

triphosphate

diphosphate

chloride

γ-L-glutamyl-[(S)-allyl]-L-cysteine

S-allyl-L-cysteine

γ-L-glutamyl-(S)-methyl-L-cysteine

γ-L-glutamyl-(S)-trans-1-propenyl-L-cysteine

S-trans-1-propenyl-L-cysteine

S-(hydroxymethyl)glutathione

thiocyanate

glutathione

S-sulfanylglutathione

5-(2-hydroxyethyl)-4-methylthiazole

2-(2-carboxy-4-methylthiazol-5-yl)ethyl phosphate

4-methyl-5-(2-phosphooxyethyl)thiazole

2-[(2R,5Z)-2-carboxy-4-methylthiazol-5(2H)-ylidene]ethyl phosphate

(R)-S-lactoylglutathione

(2Z)-2-aminobut-2-enoate

2-aminoprop-2-enoate

cadaverine

L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimeloyl-D-alanine

L-alanyl-γ-D-glutamyl-meso-diaminopimelate

D-alanyl-D-alanine

γ-L-glutamyl-L-cysteine

L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimeloyl-D-alanyl-D-alanine

4-hydroxybenzoate

urate

salicyl-6-hydroxy-2-cyclohexene-on-oyl

6-hydroxy-2-cyclohexen-one-carboxylate

hydroquinone

6-methoxy-3-methyl-2-all-trans-octaprenyl-1,4-benzoquinol

2-methoxy-6-all trans-octaprenyl-1,4-benzoquinol

luteolin

2,3-dihydroxybenzoate

protocatechuate

salicylate

4-aminobenzoate

preQ₀

(R)-lipoate

coenzyme A

tetrahydropteroyl tri-L-glutamate

5-methyltetrahydropteroyl tri-L-glutamate

7,8-dihydrofolate monoglutamate

riboflavin

nicotinate

thiamine

all-trans-retinol

(25S)-3-oxocholest-4-en-26-oate

(25S)-3-oxocholest-4-en-26-oyl-CoA

glycocholate

cholate

methyl (indol-3-yl)acetate

(indol-3-yl)acetate

4,4'-diapolycopenedioate glycosyl diester

geranyl acetate

butyl acetate

D-glucono-1,5-lactone

all-trans-retinyl palmitate

(S)-3-hydroxy-3-methylglutaryl-CoA

CoA-disulfide

isobutanoyl-CoA

3'-dephospho-CoA

succinyl-CoA

2-methylacetoacetyl-CoA

4-hydroxybutanoyl-CoA

(E)-glutaconyl-CoA

α-linolenoyl-CoA

linoleoyl-CoA

acetyl-CoA

malonyl-CoA

crotonyl-CoA

phytenoyl-CoA

oleoyl-CoA

ω-carboxy-(9Z)-octadec-9-enoyl-CoA

18-hydroxylinoleoyl-CoA

7-hydroxylauroyl-CoA

18-hydroxyoleoyl-CoA

18-hydroxystearoyl-CoA

16-hydroxypalmitoyl-CoA

(S)-3-hydroxybutanoyl-CoA

(3R)-3-hydroxybutanoyl-CoA

(Z)-15-tetracosenoyl-CoA

butanoyl-CoA

propanoyl-CoA

octanoyl-CoA

lauroyl-CoA

decanoyl-CoA

pristanoyl-CoA

cis-vaccenoyl-CoA

myristoyl-CoA

palmitoleoyl-CoA

stearoyl-CoA

palmitoyl-CoA

acetoacetyl-CoA

3-oxopentanoyl-CoA

acetamide

5-amino-4-imidazolecarboxyamide

5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide

Gro-P-ManNAc-GlcNAc-PP-undecaprenol

4,4'-diapolycopenedioate

chorismate

(3E)-2-oxohex-3-enedioate

fumarate

succinate

L-aspartate

α,ω-9Z-octadecenedioate

pyruvate

acetate

formate

propanoate

(S)-lactate

(R)-lactate

butanoate

octanoate

laurate

decanoate

7-hydroxylaurate

4-hydroxybutanoate

sophorosyloxydocosanoate

13-sophorosyloxydocosanoate 6',6''-diacetate

13-[O(2')-β-D-glucopyranosyl-β-D-glucopyranosyloxy]docosanoate O(6'')-acetate

18-hydroxyoleate

18-hydroxystearate

16-hydroxypalmitate

(15Z)-tetracosenoate

oleate

α-linolenate

linoleate

stearate

palmitate

phytenate

1-palmitoyl-2-cis-vaccenoyl phosphatidate

1,2-dicis-vaccenoyl-phosphatidate

1-cis-vaccenoyl-2-palmitoleoyl-sn-glycerol-3-phosphate

1-myristoyl-2-palmitoleoyl-sn-glycerol 3-phosphate

1-palmitoyl-2-palmitoleoyl-sn-glycerol 3-phosphate

D-gluconate

(R)-pantoate

orotate

D-mannonate

(S)-1-pyrroline-5-carboxylate

D-tagaturonate

β-D-glucuronate

aldehydo-D-galacturonate

L-α-amino-ε-keto-pimelate

carbamate

L-serine

β-alanine

L-leucine

L-proline

L-glutamine

L-alanine

glycine

D-glutamate

L-glutamate

L-lysine

L-arginine

L-tyrosine

D-aspartate

D-alanine

S-sulfanyl-L-cysteine

L-aspartyl-4-phosphate

3-phospho-L-serine

S-methyl-L-cysteine

N-carbamoyl-L-aspartate

N-acetyl-L-ornithine

N-acetyl-L-glutamate

N-acetyl-L-methionine

trans-4-hydroxy-L-proline

L-threonine

L,L-diaminopimelate

L-asparagine

L-cystathionine

L-ornithine

L-isoleucine

L-valine

L-methionine

L-cysteine

L-citrulline

L-cystine

L-canaline

L-homoserine

O-phospho-L-homoserine

S-adenosyl-L-methionine

S-adenosyl-L-homocysteine

L-glutamate-5-semialdehyde

O-succinyl-L-homoserine

L-aspartate 4-semialdehyde

meso-diaminopimelate

2-oxobutanoate

2-oxoglutarate

sn-glycero-3-phosphoethanolamine

glycerophosphoglycerol

glycerophosphoserine

glycerol

D-mannitol 1-phosphate

butan-1-ol

methanol

ethanol

geraniol

4,4'-diaponeurosporenoate

4,4'-diaponeurosporenal

all-trans-4,4'-diaponeurosporene

all-trans-4,4'-diapophytofluene

all-trans-4,4'-diapo-ζ-carotene

geranyl diphosphate

trans,octacis-decaprenyl phosphate

mono-trans,octa-cis-decaprenyl diphosphate

4,4'-diapolycopen-4,4'-dial

all-trans-4,4'-diapolycopene

di-trans,octa-cis-undecaprenyl phosphate

all-trans-octaprenyl diphosphate

geranylgeranyl diphosphate

all-trans-heptaprenyl diphosphate

di-trans,octa-cis-undecaprenyl diphosphate

3-octaprenyl-4-hydroxybenzoate

1-(18-hydroxyoleoyl)-sn-glycrol 3-phosphate

1-oleoyl-sn-glycerol 3-phosphate

1-myristoyl-sn-glycerol 3-phosphate

1-palmitoyl-sn-glycerol 3-phosphate

1-cis-vaccenoyl-sn-glycerol-3-phosphate

1-[18-hydroxyoeoyl]-2-[18-hydroxy-lioleoyl]-sn-glycerol 3-phosphate

1-palmitoyl-2-myristoyl phosphatidate

1,2-dimyristoyl-sn-glycerol 3-phosphate

dioleoyl phosphatidate

staphyloxanthin

streptothricin F

3-benzyl-3,6-dihydroxy-6-(hydroxymethyl)-diketopiperazine

3-benzyl-3,6 -bis(glutathione)- 6-(hydroxymethyl)-diketopiperazine

1-(β-D ribofuranosyl)nicotinamide

maltotriose

raffinose

maltotetraose

stachyose

maltopentaose

maltoheptaose

maltohexaose

sucrose

β-D-fructofuranose

aldehydo-D-ribose

β-D-ribofuranose

α-D-ribofuranose

β-D-ribopyranose

N-acetyl-α-D-muramoyl-L-alanine(1-)

N-acetylmuramate

N-acetyl-α-D-glucosamine 1-phosphate

N-acetyl-β-D-glucosamine

D-glyceraldehyde

α-D-glucopyranose

β-D-glucopyranose

α-D-galactopyranose

β-D-galactopyranose

1-O-acetyl-α-maltose

decaprenyl-diphospho-N-acetylmuramoyl-pentapeptide

undecaprenyl-diphospho-N-acetylmuramoyl-L-alanyl-γ-D-glutamyl-L-lysyl- D-alanine

a peptidoglycan dimer (S. aureus)

decaprenyl-pyrophosphoryl-(N-acetylglucosamine)-N-acetylmuramyl-(pentapeptide)

a peptidoglycan dimer (mycobacteria)

a peptidoglycan dimer (E. faecium, tetrapeptide)

a peptidoglycan dimer (E. faeciums)

a peptidoglycan dimer with pentapeptide stems (meso-diaminopimelate containing)

a peptidoglycan dimer with pentapeptide stem (meso-diaminopimelate containing)

ditrans,octacis-undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl-L-alanyl-γ-D-isoglutaminyl-L-lysyl-D-alanyl-D-alanine

ditrans,octacis-undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl-L-alanyl-γ-D-isoglutaminyl-N-(β-D-asparatyl)-L-lysyl-D-alanyl-D-alanine

ditrans,octacis-undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl-L-alanyl-γ-D-isoglutaminyl-L-lysyl-(glycyl)₅-D-alanyl-D-alanine

ditrans,octacis-undecaprenyldiphospho-[(N-acetyl-β-D-glucosaminyl)-(1,4)-]-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimeloyl-D-alanyl-D-alanine

ditrans,octacis-undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl-L-alanyl-γ-D-isoglutaminyl-N-(β-D-asparaginyl)-L-lysyl-D-alanine

ditrans,octacis-undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl-L-alanyl-γ-D-isoglutaminyl-N-(β-D-asparaginyl)-L-lysyl-D-alanyl-D-alanine

GlcNAc-1,6-anhMurNAc-L-Ala-γ-D-Glu-DAP-D-Ala

D-ribulose-1,5-bisphosphate

undecaprenyldiphospho-N-acetylmuramoyl-L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimeloyl-D-alanyl-D-alanine

undecaprenyl-diphospho-N-acetylmuramoyl-L-alanyl-γ-D-glutamyl-L-lysyl- D-alanyl-D-alanine

N,N'-diacetylchitobiose 6'-phosphate

N-monoacetylchitobiose 6'-phosphate

UDP-α-D-glucose

ADP-α-D-glucose

UDP-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-L-lysine

UDP-N-acetyl-α-D-muramoyl-L-alanine

UDP-N-acetyl-α-D-muramoyl-L-alanyl-D-glutamate

UDP-α-D-glucuronate

UDP-N-acetyl-α-D-muramate

UDP-α-D-galactose

UDP-N-acetyl-α-D-glucosamine-enolpyruvate

UDP-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-L-lysyl-D-alanine

UDP-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimeloyl-D-alanyl-D-alanine

UDP-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-L-lysyl-D-alanyl-D-alanine

UDP-N-acetyl-α-D-muramoyl-L-alanyl-γ-D-glutamyl-meso-2,6-diaminopimelate

UDP-N-acetyl-α-D-glucosamine

4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol

2-phospho-4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol

D-glyceraldehyde 3-phosphate

α-D-glucopyranose 1-phosphate

1-(o-carboxyphenylamino)-1'-deoxyribulose 5'-phosphate

D-erythrose 4-phosphate

D-sedoheptulose 7-phosphate

5-phospho-α-D-ribose 1-diphosphate

D-tagatofuranose 1,6-bisphosphate

β-D-fructose 1,6-bisphosphate

salicin 6-phosphate

arbutin-6-phosphate

D-fructose 6-phosphate

β-D-fructofuranose 6-phosphate

α-D-glucose 6-phosphate

β-D-glucose 6-phosphate

D-xylulose 5-phosphate

D-ribulose 5-phosphate

aldehydo-D-ribose 5-phosphate

β-D-ribose 5-phosphate

α-D-ribose 5-phosphate

α-D-ribose-1-phosphate

2-deoxy-α-D-ribose 1-phosphate

α-D-galactose 1-phosphate

β-D-glucopyranose 1-phosphate

β-D-fructofuranose 1-phosphate

methyl β-D-glucoside 6-phosphate

D-altronate

methylglyoxal

formaldehyde

acetaldehyde

cytidine 2',3'-cyclic monophosphate

uridine 2'3'-cyclic monophosphate

uridine 3'-monophosphate

cytidine-3'-monophosphate

dCMP

dTDP

dTTP

dUTP

CTP

dCTP

UTP

dTMP

dUMP

cytosine

uracil

dUDP

UDP

dCDP

CDP

5-fluorouracil

UMP

CMP

uridine

cytidine

2'-deoxycytidine

thymidine

2'-deoxyuridine

thymine

adenine

guanine

hypoxanthine

isoguanine

preQ₁

xanthosine

guanosine

inosine

adenosine

2'-deoxyinosine

2'-deoxyadenosine

2'-deoxyguanosine

ITP

GTP

ATP

IDP

GDP

ADP

XMP

IMP

GMP

AMP

dITP

dGTP

dATP

dIDP

dADP

dGDP

6,7-dimethyl-8-(1-D-ribityl)lumazine

(7,8-dihydropterin-6-yl)methyl diphosphate

7,8-dihydropteroate

(3R)-vestitone

guanosine 2',3'-cyclic monophosphate

adenosine 2',3'-cyclic monophosphate

8-oxo-GTP

8-oxo-dGTP

cyclic-AMP

adenosine 3'-monophosphate

guanosine 3'-monophosphate

pppGpp

ppGpp

adenylo-succinate

5-fluorocytosine

cyclic di-3',5'-guanylate

5-hydroxy-CTP

2-hydroxy-dATP

β-nicotinamide D-ribonucleotide