Improved chemical synthesis and enzymatic assay of delta-1-pyrroline-5-carboxylic acid.

Δ¹-Pyrroline-5-car?ylic acid, an intermediate in both the biosynthesis and degradation ofl-proline, has been synthesized by the periodate oxidation of hydroxylysine and isolated as a pure compound, as indicated by enzymatic assay with pyrroline-5-car?ylate reductase fromEscherichia coli. Some features of the instability in solution ofΔ¹-pyrroline-5-car?ylic acid have been studied, leading to the conclusion that the rate of decomposition is sensitive to concentration of the compound. Colorimetric assay witho-aminobenzaldehyde was found to be an inadequate measure of the pyrroline compound in partially decomposed solutions.