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

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

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

enol-phenylpyruvate

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

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

ammonia

4-oxoglutaramate

1-piperideine 6-carboxylate

L-histidinol phosphate

(2R,3S)-3-methylmalate

citraconate

S-ribosyl-L-homocysteine

2-hydroxy-6-oxocyclohexane-1-carbonyl-CoA

autoinducer 2

3-hydroxypropanoate

cyclohexane-1-carbonyl-CoA

cyclohexane-1-carboxylate

3-oxopimeloyl-CoA

3-hydroxypimeloyl-CoA

6-oxocyclohex-1-ene-1-carbonyl-CoA

6-hydroxycyclohex-1-ene-1-carbonyl-CoA

cyclohex-1,5-diene-1-carbonyl-CoA

crotonate

5,6-dimethylbenzimidazole

dialurate

(R)-1-amino-2-propanol O-2-phosphate

2-(α-hydroxyethyl)thiamine diphosphate

thiamine diphosphate

N⁵-carboxyaminoimidazole ribonucleotide

creatinine

4-amino-2-methyl-5-pyrimidinemethanol

4-fumaryl-acetoacetate

(R)-mevalonate diphosphate

acetoacetate

(L-threonylcarbamoyl)adenylate

benzoylsuccinyl-CoA

3-[(3aS,4S,5R,7aS)-5-hydroxy-7a-methyl-1-oxo-octahydro-1H-inden-4-yl]-3-hydroxypropanoyl-CoA

3-[(3aS,4S,5R,7aS)-5-hydroxy-7a-methyl-1-oxo-octahydro-1H-inden-4-yl]-3-oxopropanoyl-CoA

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

(2-carboxy-2,5-dihydro-5-oxofuran-2-yl)-acetate

(4,5-dihydro-5-oxofuran-2-yl)-acetate

α-ribazole

α-ribazole 5'-phosphate

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

(S)-dihydroorotate

4-aminobutanoate

succinate semialdehyde

3-oxopropanoate

(R)-mevalonate

(R)-5-phosphomevalonate

γ-L-glutamyl 5-phosphate

(S)-2-amino-6-oxohexanoate

S-adenosyl 3-(methylsulfanyl)propylamine

nicotinate adenine dinucleotide

5-dehydro-4-deoxy-D-glucarate

isopentenyl diphosphate

prenyl diphosphate

4-amino-4-deoxychorismate

hydrogenobyrinate

hydrogenobyrinate a,c-diamide

1,6-anhydro-N-acetyl-β-muramate

N-acetyl-D-muramate 6-phosphate

3-(4-hydroxyphenyl)-3-oxo-propanoyl-CoA

S-methyl-5'-thioadenosine

L-canavanine

urea

formamide

nigerose

N-acetyl-L-glutamate 5-semialdehyde

N-acetylglutamyl-phosphate

prephenate

CO₂

luteolin 7-O-β-D-glucuronide

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

luteolin 7-O-β-D-diglucuronide

5-oxo-L-proline

D-erythro-imidazole-glycerol-phosphate

imidazole acetol-phosphate

4'-phosphopantetheine

(R)-4'-phosphopantothenate

histidinal

(R)-4'-phosphopantothenoyl-L-cysteine

histidinol

2-maleylacetate

urocanate

4-imidazolone-5-propanoate

L-tartrate

oxaloacetate

carbamoyl phosphate

oxalosuccinate

α-D-glucosamine 1-phosphate

porphobilinogen

N²-succinyl-L-glutamate 5-semialdehyde

N²-succinylglutamate

4-acetamidobutanal

adenosine 5'-phosphosulfate

4-acetamidobutanoate

adenosine 5'-phosphoselenate

(R)-2,3-dihydroxy-3-methylpentanoate

(S)-3-methyl-2-oxopentanoate

2-dehydropantoate

H₂

carbon monoxide

hydrogen peroxide

5-hydroxytryptophol

5-hydroxyindole acetaldehyde

3-dehydroquinate

3-dehydroshikimate

3-methyl-2-oxobutanoate

(2S)-2-isopropylmalate

2-dehydro-3-deoxy-D-gluconate

phosphoenolpyruvate

5-enolpyruvoyl-shikimate 3-phosphate

shikimate

3-methoxy-4-hydroxyphenylglycolaldehyde

shikimate 3-phosphate

indole-3-glycol

indole-3-glycol aldehyde

H₂O

isobutanol

3-methylbutanol

3-methylbutanal

2-methylbutanol

2-methylbutanal

2-phenylethanol

3-ureidopropanoate

(S)-4-amino-5-oxopentanoate

5-aminolevulinate

orotidine 5'-phosphate

coproporphyrinogen III

(E)-2-benzylidenesuccinyl-CoA

2-carboxymethyl-3-hydroxyphenylpropanoyl-CoA

3S-(4-hydroxyphenyl)-3-hydroxy-propanoyl-CoA

(E)-4-coumaroyl-CoA

2,3-didehydroadipyl-CoA

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

thiamine phosphate

β-nicotinate D-ribonucleotide

quinolinate

N-acetyl-D-galactosamine 6-phosphate

D-galactosamine-6-phosphate

citrate

5-carboxymethyl-2-hydroxymuconate

S-methyl-5-thio-α-D-ribose 1-phosphate

5-(methylsulfanyl)-ribulose 1-phosphate

ethanolamine

N¹-(5-phospho-β-D-ribosyl)glycinamide

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

5-phospho-β-D-ribosylamine

N²-formyl-N¹-(5-phospho-β-D-ribosyl)glycinamide

2-(formamido)-N¹-(5-phospho-β-D-ribosyl)acetamidine

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

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

O-ureido-L-homoserine

canavaninosuccinate

L-arginino-succinate

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

hydroxypyruvate

3-keto-β-D-galactose

2-oxoglutaramate

N-(5-phosphoribosyl)-anthranilate

anthranilate

(indol-3-yl)pyruvate

(indol-3 yl)acetyl-CoA

preuroporphyrinogen

2-isopropylmaleate

(S)-2-aceto-2-hydroxybutanoate

(S)-2-acetolactate

(2R,3S)-3-isopropylmalate

(2S)-2-isopropyl-3-oxosuccinate

4-methyl-2-oxopentanoate

3-ethylmalate

2-oxovalerate

4-phosphooxy-L-threonine

(2S)-2-amino-3-oxo-4-phosphooxybutanoate

3-amino-1-hydroxyacetone 1-phosphate

itaconate

glycerone phosphate

cobalt-factor III

cobalt-precorrin-3

cobalt-sirohydrochlorin

cobalt-precorrin-7

cobalt-precorrin-8

cobalt-precorrin-6B

cobalt-precorrin-5B

cobalt-precorrin-6A

cobalt-precorrin-4

cobalt-precorrin-5A

adenosyl-cobinamide phosphate

adenosylcobyrate

adenosylcobinamide-GDP

adenosylcobalamin 5'-phosphate

cob(II)yrinate c-monoamide

cob(II)yrinate a,c-diamide

cobyrinate

cob(I)alamin

adenosylcobalamin

cob(I)inamide

adenosylcobinamide

cob(I)yrinate a,c-diamide

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

protoheme

nitrous oxide

hydrogen cyanide

uroporphyrinogen-I

protoporphyrinogen IX

uroporphyrinogen-III

siroheme

Hg⁰

oxygen

sn-glycerol 3-phosphate

2,3-diphospho-D-glycerate

3-phospho-D-glyceroyl-phosphate

(R)-glycerate

3-phospho-D-glycerate

2-phospho-D-glycerate

dTDP-4-dehydro-6-deoxy-α-D-glucopyranose

(2R)-2,3-dihydroxy-3-methylbutanoate

(R)-citramalate

(S)-citramalate

5,10-methenyltetrahydrofolate mono-L-glutamate

2-octaprenylphenol

nitric oxide

superoxide

dimethyl sulfide

methionol

3-(methylsulfanyl)propanal

thiocyanate

glutathione

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

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

5-(2-hydroxyethyl)-4-methylthiazole

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

L-cysteate

3-sulfopyruvate

ammonium

H⁺

Co²⁺

Hg²⁺

Fe²⁺

trimethyl sulfonium

sulfate

nitrite

nitrate

thiosulfate

sulfite

molybdate

selenate

hydrogencarbonate

trithionate

OH^-

hydrogensulfite

phosphate

diphosphate

triphosphate

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

agmatine

spermine

putrescine

dehydrospermidine

spermidine

sn-glycero-3-phosphoethanolamine

glycerophosphoserine

glycerophosphoglycerol

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

5-amino-4-imidazolecarboxyamide

1-(5-phospho-β-D-ribosyl)-5-[(5-phosphoribosylamino)methylideneamino]imidazole-4-carboxamide

phosphoribulosylformimino-AICAR-phosphate

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

24-hydroxy-3-oxocholest-4-en-26-oyl-CoA

3,24-dioxocholest-4-en-26-oyl-CoA

3-oxo-4-pregnene-20-carboxyl-CoA

3,22-dioxochol-4-en-24-oyl-CoA

(indol-3-yl)acetate

2-methylbutanoyl-CoA

4-hydroxybutanoyl-CoA

3-hydroxypropanoyl-CoA

acryloyl-CoA

malonyl-CoA

glutaryl-CoA

(E)-glutaconyl-CoA

(3R)-hydroxy- 5-cis, 7-trans-tetradecadienoyl-CoA

(3R)-hydroxy-5-trans-dodecenoyl-CoA

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

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-hexanoyl-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3-oxooctanoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-butanoyl-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3-oxohexanoyl)-CoA

(+)-7-epi-jasmonoyl-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3-oxobutanoyl)-CoA

4-hydroxybenzoyl-CoA

6-cis, 3-oxo-tridecenoyl-CoA

4-cis-undecenoyl-CoA

6-trans-3-oxo-tridecenoyl-CoA

4-trans-undecenoyl-CoA

4-trans-3-oxo-undecenoyl-CoA

5-cis, 7-trans-3-oxo-tetradecadienoyl-CoA

(3Z,5E)-dodeca-3,5-dienoyl-CoA

(5E)-3-oxo-dodec-5-enoyl-CoA

(3E)-dec-3-enoyl-CoA

2-methylacetoacetyl-CoA

acetyl-CoA

isobutanoyl-CoA

methylacrylyl-CoA

(2E,5Z)-tetradecenoyl-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3R-hydroxyoctanoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(E-octa-2-enoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3R-hydroxyhexanoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(E-hexa-2-enoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(3R-hydroxybutanoyl)-CoA

3-oxo-2-(cis-2'-pentenyl)-cyclopentane-1-(E-buta-2-enoyl)-CoA

(2S,3S)-3-hydroxy-2-methylbutanoyl-CoA

3-hydroxyisovaleryl-CoA

(E)-2-methylcrotonoyl-CoA

2-trans,6-cis-tridecadienoyl-CoA

(3R)-hydroxy, 6-cis-tridecenoyl-CoA

(3E)-undec-2-enoyl-CoA

(3R)-hydroxy-undecanoyl-CoA

2-trans-6-trans-tridecadienoyl-CoA

(3R)-hydroxy, 6-trans-tridecenoyl-CoA

2-trans, 4-trans-undecadienoyl-CoA

(3R)-hydroxy, 4-trans-undecenoyl-CoA

2-trans-nonenoyl-CoA

(3R)-hydroxy-nonanoyl-CoA

(3S)-hydroxyadipyl-CoA

3'-dephospho-CoA

itaconyl-CoA

succinyl-CoA

(R)-methylmalonyl-CoA

(S)-methylmalonyl-CoA

crotonyl-CoA

(2E)-dec-2-enoyl-CoA

(2E)-oct-2-enoyl-CoA

(3Z)-dodec-3-enoyl-CoA

(S)-3-hydroxybutanoyl-CoA

(S)-3-hydroxyhexanoyl-CoA

(S)-3-hydroxydecanoyl-CoA

(S)-3-hydroxyoctanoyl-CoA

(S)-3-hydroxyhexadecanoyl-CoA

(S)-3-hydroxy-(5Z)-tetradecenoyl-CoA

(3R)-3-hydroxybutanoyl-CoA

butanoyl-CoA

propanoyl-CoA

octanoyl-CoA

lauroyl-CoA

decanoyl-CoA

hexanoyl-CoA

3-oxoadipyl-CoA

3-oxopentanoyl-CoA

acetoacetyl-CoA

3-oxohexanoyl-CoA

3-oxodecanoyl-CoA

3-oxododecanoyl-CoA

3-oxooctanoyl-CoA

3-oxo-palmitoyl-CoA

3-oxo-myristoyl-CoA

3-oxo-(5Z)-tetradecenoyl-CoA

(S)-3-hydroxy-isobutanoyl-CoA

trans-dienelactone

cis-dienelactone

FMNH₂

FMN

(S)-NADHX

(R)-NADHX

NADH

NADPH

NAD⁺

NADP⁺

menaquinol-8

demethylmenaquinol-8

molybdopterin

coenzyme A

MoO₂-molybdopterin cofactor

tetrahydropteroyl tri-L-glutamate

5,6,7,8-tetrahydrofolate

5,10-methylenetetrahydropteroyl mono-L-glutamate

10-formyl-tetrahydrofolate mono-L-glutamate

5-methyltetrahydropteroyl mono-L-glutamate

5-methyltetrahydropteroyl tri-L-glutamate

(6S)-5-formyl-tetrahydrofolate mono-L-glutamate

7,8-dihydrofolate monoglutamate

nicotinate

riboflavin

pyridoxal 5'-phosphate

menadione

(S)-1-pyrroline-5-carboxylate

precorrin-2

precorrin-1

sirohydrochlorin

hydantoin

reduced riboflavin

cyclic pyranopterin phosphate

6-(hydroxymethyl)-7,8-dihydropterin

molybdopterin adenine dinucleotide

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

7,8-dihydroneopterin 3'-triphosphate

7,8-dihydropteroate

adenine

2'-deoxyguanosine

2'-deoxyadenosine

2'-deoxyinosine

inosine

adenosine

dAMP

dGMP

dIMP

dITP

dGTP

dATP

dIDP

dGDP

dADP

ADP

IDP

GDP

GMP

AMP

XMP

IMP

ATP

XTP

ITP

GTP

orotate

uracil

dCMP

dUMP

5,6-dihydrouracil

5,6-dihydrothymine

dTMP

UDP

dUDP

dTDP

dTTP

dCDP

CDP

CTP

UTP

dCTP

dUTP

UDP-α-D-galactofuranose

UDP-α-D-glucose

UDP-α-D-galactose

UDP-N-acetyl-α-D-glucosamine

dTDP-β-L-rhamnose

dTDP-α-D-glucose

dTDP-4-dehydro-β-L-rhamnose

cytidine

uridine

thymidine

2'-deoxycytidine

2'-deoxyuridine

thymine

CMP

UMP

luteolin

(indole-3-yl)acetonitrile

salicylaldehyde

4-hydroxybenzoate

4-tyrosol

2-[(1R,6S)-1,6-dihydroxycyclohexa-2,4-dien-1-yl]acetyl-coA

3-methoxy-4-hydroxyphenylglycol

benzaldehyde

(4-hydroxyphenyl)acetaldehyde

phenylacetaldehyde

indole

(1S,2R)-1-C-(indol-3-yl)glycerol 3-phosphate

menadiol

3,4-dihydroxyphenylglycol

3,4-dihydroxyphenylglycolaldehyde

salicylate

benzoate

4-aminobenzoate

chorismate

succinate

fumarate

L-aspartate

(S)-malate

D-galactarate

3-(carbamoylamino)-2-methylpropanoate

cis-homoaconitate

cis-aconitate

(2R,3S)-2-methylisocitrate

(2R)-homocitrate

(3E,5R)-5-carboxy-2-oxohept-3-enedioate

(2S,3S)-2-methylcitrate

cis-2-methylaconitate

D-threo-isocitrate

4-hydroxybutanoate

(R)-lactate

propanoate

acetate

formate

pyruvate

octanoate

apo-4'-lycopenoate

phytenate

leukotriene-E4

leukotriene-D4

(R)-pantoate

D-mannonate

β-D-glucuronate

3-phenyl-2-oxopropanoate

2-oxobutanoate

2-oxoglutarate

glyoxylate

L-serine

creatine

β-alanine

L-alanine

L-leucine

glycine

L-glutamine

L-proline

L-glutamate

L-lysine

L-histidine

L-arginine

L-cysteine

L-tyrosine

L-threonine

L-asparagine

L-phenylalanine

L-tryptophan

2-hydroxy-5-oxoproline

L-saccharopine

L-aspartyl-4-phosphate

N-carbamoylglycine

formyl-L-isoglutamine

N-formimino-L-glutamate

N-acetyl-L-glutamate

N-carbamoyl-L-aspartate

L-citrulline

L-valine

L-isoleucine

L-glutamate-5-semialdehyde

L-canaline

O-succinyl-L-homoserine

L-homocysteine

O-phospho-L-homoserine

S-adenosyl-L-methionine

S-adenosyl-L-homocysteine

L-homoserine

L-aspartate 4-semialdehyde

L-ornithine

hypoglycin A

meso-diaminopimelate

L-methionine

L-isoglutamine

L,L-diaminopimelate

L-cystathionine

a coenzyme-A group

methylglyoxal

diacetyl

butan-1-al

1-octanal

acetaldehyde

1-propanal

isobutanal

(R)-lactaldehyde

phytenal

D-glyceraldehyde

α-D-glucopyranose

β-D-glucopyranose

β-D-galactopyranose

α-D-galactopyranose

butan-1-ol

ethanol

propan-1-ol

phytol

glycerol

myo-inositol

scyllo-inosose

1-amino-1-deoxy-scyllo-inositol

galactinol

1D-myo-inositol 1-monophosphate

1D-myo-inositol 3-monophosphate

apo-4'-lycopenal

(2E,6E)-farnesyl diphosphate

phytyl diphosphate

3-octaprenyl-4-hydroxybenzoate

di-trans,octa-cis-undecaprenyl phosphate

all-trans-octaprenyl diphosphate

geranylgeranyl diphosphate

di-trans,octa-cis-undecaprenyl diphosphate

XLLG xyloglucan oligosaccharide

XLXG xyloglucan oligosaccharide

XXLG xyloglucan oligosaccharide

XXXG xyloglucan oligosaccharide

raffinose

maltotriose

maltotetraose

maltoheptaose

maltohexaose

maltopentaose

α-maltose

sucrose

α-lactose

N-acetyl-α-D-glucosamine 1-phosphate

keto-D-fructose

β-D-fructofuranose

3'-ketolactose

sucrose 6^F-phosphate

ADP ribose 1'',2''-cyclic phosphate

ADP ribose 1''-phosphate

ADP-D-ribose

D-glyceraldehyde 3-phosphate

α-D-glucopyranose 1-phosphate

5-phospho-α-D-ribose 1-diphosphate

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

D-erythrose 4-phosphate

β-D-fructose 1,6-bisphosphate

D-fructose 6-phosphate

β-D-fructofuranose 6-phosphate

α-D-mannopyranose 6-phosphate

β-D-glucose 6-phosphate

α-D-glucose 6-phosphate

D-ribulose 5-phosphate

aldehydo-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

D-altronate

cyclic-AMP

1-(5-phospho-β-D-ribosyl)-AMP

1-(5-phospho-β-D-ribosyl)-ATP

5'-deoxyadenosine

adenylo-succinate

reduced β-nicotinamide D-ribonucleotide

β-nicotinamide D-ribonucleotide

hypoglycin B

N-acetyl-L-glutaminyl-L-glutamine

N-acetyl-L-glutaminyl-L-glutamine amide

L-cysteinylglycine

2-iminobutanoate

2-iminosuccinate