Presence and origin of large amounts of d-proline in the urine of mutant mice lacking d-amino acid oxidase activity

Kenji Hamase, Sayaka Takagi, Akiko Morikawa, Ryuichi Konno, Akira Niwa, Kiyoshi Zaitsu

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


Using a column-switching HPLC system combining a micro-ODS column and a chiral column, the amounts of d-proline (d-Pro) have been determined in 18 tissues, plasma and urine of mice. To avoid the enzymatic degradation of d-amino acids in vivo, a mutant mouse strain lacking d-amino acid oxidase activity (ddY/DAO- mouse) was used. In the brain, relatively large amounts of d-Pro were observed in the anterior pituitary, posterior pituitary and pineal glands. In the peripheral tissues, the amounts of d-Pro were high in the pancreas and kidney. Above all, it is surprising that the ddY/DAO - mice excreted large amounts of d-Pro in their urine (433 nmol/mL, 20 times that of l-Pro). The origin of d-Pro has also been investigated. By comparing germ-free mice and gnotobiotic mice, intestinal bacteria were shown to have no effect on the urinary d-Pro amount. Concerning the dietary origin, a notable amount of d-Pro was still excreted in the urine after starvation for 4 days, suggesting that some of the d-Pro is produced in the mice. Age-dependent changes in the urinary d-Pro amount have also been investigated from the postnatal 1st month up to 12 months, and ddY/DAO- mice were found to excrete large amounts of d-Pro in the urine constantly throughout their lives.

Original languageEnglish
Pages (from-to)705-711
Number of pages7
JournalAnalytical and Bioanalytical Chemistry
Issue number3
Publication statusPublished - Oct 2006

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry


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