Kollagenhydroxylierung

Kollagenhydroxylierung is a critical post-translational modification that occurs in the synthesis of collagen. This process involves the enzymatic addition of hydroxyl groups to specific proline and lysine residues within the growing collagen polypeptide chains. The key enzyme responsible for this hydroxylation is prolyl hydroxylase, which requires iron, alpha-ketoglutarate, oxygen, and vitamin C as cofactors. Lysyl hydroxylase is responsible for the hydroxylation of lysine residues.

The hydroxylation of proline residues is particularly important for the stability of the collagen triple helix. The hydroxyl groups form hydrogen bonds with neighboring amino acids, stabilizing the helical structure and preventing its unwinding. Hydroxylated proline, known as hydroxyproline, constitutes a significant portion of the amino acid composition of collagen and is a key indicator of collagen content in biological samples.

Hydroxylation of lysine residues is essential for the cross-linking of collagen molecules. Hydroxylated lysine residues can be further oxidized to aldehydes, which then react with other modified lysine residues to form covalent cross-links between collagen fibrils. These cross-links are vital for the tensile strength and structural integrity of collagenous tissues, such as bone, cartilage, and skin.

Deficiencies in vitamin C, a crucial cofactor for prolyl hydroxylase, lead to impaired collagen synthesis and a condition known as scurvy. In scurvy, the lack of hydroxylation results in unstable collagen, leading to symptoms such as bleeding gums, poor wound healing, and joint pain. Therefore, Kollagenhydroxylierung is indispensable for the proper formation and function of connective tissues throughout the body.