Research area

Metabolites and small molecules

These compounds are not peptides: NAD+, glutathione and L-carnitine are metabolites, and 5-Amino-1MQ and SLU-PP-332 are synthetic small molecules used as tool compounds.

NAD+ is a dinucleotide coenzyme, glutathione is a tripeptide thiol with a γ-peptide bond, and L-carnitine is a quaternary ammonium compound. 5-Amino-1MQ is a quinolinium inhibitor of nicotinamide N-methyltransferase, and SLU-PP-332 is an agonist of the estrogen-related receptors.

Because these compounds are small molecules, they are analysed differently from peptides: HPLC-UV at wavelengths specific to the chromophore, enzymatic assays, NMR, and water-content methods rather than amino acid analysis.

Compounds in this group

Compound	Type	Formula	Average mass (g/mol)	Listings
5-Amino-1MQ	Small molecule	C₁₀H₁₁N₂⁺	159.21	3
Glutathione	Small molecule	C₁₀H₁₇N₃O₆S	307.32	2
L-carnitine	Small molecule	C₇H₁₅NO₃	161.20	3
NAD+	Small molecule	C₂₁H₂₇N₇O₁₄P₂	663.43	2
SLU-PP-332	Small molecule	C₁₈H₁₄N₂O₂	290.32	1

Analytical points for this group

Check the form supplied: free acid or salt for NAD+, reduced or oxidised for glutathione, L or D enantiomer for carnitine, and the counter-ion for 5-Amino-1MQ.
NAD+ absorbs at 260 nm and degrades in solution, especially at alkaline pH.
Glutathione oxidises to the disulfide dimer GSSG (about 612.6 Da) in air.
SLU-PP-332 is an acylhydrazone; E/Z isomers may separate by HPLC.

Guides

GuidePeptide Analytical Methods Compared: HPLC, LC-MS, Amino Acid Analysis, NMR and Karl Fischer

Which test answers which question: identity, purity, content, water, counter-ion, stereochemistry and sterility, with the strengths and limits of…

GuideHow to Read a Peptide Certificate of Analysis (COA)

A practical laboratory checklist for reviewing peptide identity, purity, content, batch details, methods, and third-party verification on a COA.

ExplainerPeptide Counter-Ions and Net Peptide Content: Why the Powder Weighs More Than the Peptide

TFA and acetate counter-ions, bound water and net peptide content explained, with a worked example of how a 1000 Da peptide becomes a 1228 Da salt.

Frequently asked questions

Which compounds are in the metabolites and small molecules group?

5-Amino-1MQ, Glutathione, L-carnitine, NAD+, SLU-PP-332.

How should a batch of a metabolites and small molecules compound be checked?

Check the form supplied: free acid or salt for NAD+, reduced or oxidised for glutathione, L or D enantiomer for carnitine, and the counter-ion for 5-Amino-1MQ. NAD+ absorbs at 260 nm and degrades in solution, especially at alkaline pH.

Other research areas

All compound references →