Prolyl 4-hydroxylase, an alpha 2 beta 2 tetramer, catalyses the formation of 4-hydroxyproline in collagens. The beta subunit is known to be identical with the enzyme protein disulphide-isomerase and to possess disulphide-isomerase activity even when present in the prolyl 4-hydroxylase tetramer. We here report that lysyl hydroxylase, a homodimer, and algal prolyl 4-hydroxylase, a monomer, do not contain detectable protein disulphide-isomerase activity. Since the hydroxylase reaction mechanisms are similar, the data suggest that the protein disulphide-isomerase activity of the vertebrate prolyl 4-hydroxylase beta subunit is unlikely to be involved in the catalytic mechanism of the hydroxylation reaction.
The catalytic mechanism of the hydroxylation reaction of peptidyl proline and lysine does not require protein disulphide-isomerase activity
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R Myllylä, D D Kaska, K I Kivirikko; The catalytic mechanism of the hydroxylation reaction of peptidyl proline and lysine does not require protein disulphide-isomerase activity. Biochem J 15 October 1989; 263 (2): 609–611. doi: https://doi.org/10.1042/bj2630609
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