STEREOCHEMISTRY OF PIPECOLIC ACID FOUND IN THE URINE AND PLASMA OF SUBJECTS WITH PEROXISOMAL DEFICIENCIES

Recently it was found that normal adults excrete pipecolic acid primar ily as the D-enantiomer even though it is present in the blood stream mainly as the L-enantiomer (i.e. > 98% L). This study of pipecolic aci d stereochemistry was extended to subjects with peroxisomal deficienci es since they are known to have high levels of pipecolic acid in their physiological fluids. Also, pipecolic acid stereochemistry was examin ed in young normal subjects since this group was not considered previo usly. It was found that the stereochemical composition of pipecolic ac id in plasma was very similar for all subjects tested (i.e. >98% of th e L-enantiomer). However, the stereochemical composition of excreted p ipecolic varied considerably. Urine samples from subjects with the mos t severe peroxisomal deficiency, i.e. cerebralhepatorenyl (Zellweger) syndrome (CHRS) contained little D-pipecolic acid. In fact the enantio meric ratios for pipecolic acid in the urine and plasma of these subje cts were very similar. This was not the case for normal subjects. Leve ls of D-pipecolic acid in the urine of subjects with 'less severe' per oxisomal deficiencies tended to be somewhat higher but they did not ap proach the levels found in normal adults. Several possible reasons for these results are discussed.