626-64-2

4-Hydroxypyridine, available from pyridylpyridinium chloride hydrochloride, is the substrate for diodone and its n-propyl ester, propyliodone. 4-Hydroxypyridine (4-HP) is a non-nucleophilic analog of the product phenol found to bind specifically to and stabilize the aminoacrylate intermediate. When 4-HP is added to Tyrosine phenol-lyase (TPL) reactions, an absorption peak at 340 nm is observed. The formation of the 340 nm peak correlates with the decay of the quinonoid intermediate peak at 505 nm, with a clean isosbestic point, and the observed rate constants show an inverse dependence on the concentration of 4-HP. These results confirm that the observed peak at 340 nm is due to the formation of the amino acrylate intermediate[1-2].

Beige crystalline powder

ChEBI: A monohydroxypyridine that is pyridine in which the hydrogen at position 4 has been replaced by a hydroxy group.

Crystallise 4-pyridone from H2O or wet CHCl3 as the monohydrate. It loses H2O on drying in vacuo over H2SO4. Store it over KOH because it is hygroscopic.[Beilstein 21 III/IV 446, 21/7 V 152.]

[1] Yates, F. S. “2.09 – Pyridines and their Benzo Derivatives: (vi) Applications.”Comprehensive Heterocyclic Chemistry 2 (1984): 511-524.
[1] Robert S Phillips, Olivia Bauer. “Characterization of aminoacrylate intermediates of pyridoxal-5’-phosphate dependent enzymes.” Methods in enzymology 685 (2023): 199–224.