Collagen hydroxylase (P4H and LH)

Collagen hydroxylases are a family of enzymes—primarily prolyl hydroxylases and lysyl hydroxylases—that catalyze the hydroxylation of specific proline or lysine residues in procollagen polypeptides. This post-translational modification is essential for the correct folding, stability, and secretion of mature collagen molecules. Prolyl hydroxylases (mainly prolyl-4-hydroxylase) create hydroxyproline, which stabilizes the collagen triple helix at physiological temperature, while lysyl hydroxylases are needed for later glycosylation and cross-linking steps. These enzymes are vital to the structural integrity of connective tissues, and their dysfunction results in a spectrum of disorders, ranging from fragile bones and skin to fibrotic diseases and tumor microenvironment alteration. Cofactors such as iron (Fe2+) and vitamin C (ascorbate) are required for their enzymatic activity[1][4][6][7][8]. Therapeutically, collagen hydroxylases are targeted for anti-fibrotic, anti-cancer, or connective tissue-related indications, but safety concerns arise due to their central role in tissue stability. Their enzymatic activities and post-translational modification products (hydroxyproline, hydroxylysine) are key biomarkers for various diseases.

Other names

Prolyl hydroxylaselysyl hydroxylaseprocollagen-proline dioxygenaseprocollagen lysine hydroxylasecollagen prolyl 4-hydroxylaseP4HLHPLOD proteins

Enzyme inhibition: Direct competitive or allosteric inhibition of hydroxylase catalytic activity, reducing collagen stability or biosynthesis. Cofactor modulation: Indirect targeting via depletion/modulation of required cofactors (ascorbate, iron). Pathway modulation: Altering cortisol signaling can upregulate related hydroxylase pathways for therapeutic effect or metabolic stability.