The stereochemical course of the hydroxylation of (S)-proline by proli
ne 4-hydroxylase from Streptomyces griseoviridus has been investigated
using (2S, 4S)-[4-H-2(1)]-proline and (2S, 4R)-[4-H-2(1)]-proline and
found to occur with retention of stereochemistry at C-4 of proline.