BIOSYNTHESIS OF ABNORMAL COLLAGENS WITH AMINO ACID ANALOGUES .I. INCORPORATION OF L-AZETIDINE-2-CARBOXYLIC ACID AND CIS-4-FLUORO-L-PROLINE INTO PROTOCOLLAGEN AND COLLAGEN

1. 1. Eight proline analogues inhibited the incorporation of [14C]proline into collagen by embryonic cartilage, apparently because the analogues competed with [14C]proline for uptake by the cells. 2. 2. l-Azetidine-2-carboxylic acid and cis-4-fluoro-l-proline were more effective than the other analogues in inhibiting [14C]proline incorporation, and they were the only analogues which decreased the extent to which [14C]proline still incorporated into protein was converted to collagen [14C]hydroxyproline. 3. 3. Direct evidence for the incorporation of l-azetidine-2-carboxylic acid into collagen was obtained with a 14C-labeled preparation of the analogue, and the results indicated that the l-azetidine-2-carboxylic acid was incorporated without significant conversion to other compounds. 4. 4. cis-Fluoroproline was similar to l-azetidine-carboxylic acid in that it decreased the ratio of [14C]hydroxyproline to total 14C in the tissue without inhibiting protocollagen proline hydroxylase; it inhibited the growth of Escherichia coli; and it resulted in the synthesis of a protocollagen which differed kinetically from normal protocollagen when incubated with protocollagen proline hydroxylase. 5. 5. The results indicated that l-azetidine-2-carboxylic acid and cis-4-fluoro-l-proline are incorporated into an abnormal protocollagen which is subsequently converted to an abnormal collagen. © 1969.