Mechanism-based inactivation of -pipecolate oxidase by a sulfur-containing substrate analog, 5-thia- -pipecolic acid

5-Thia- -pipecolic acid, (S)-1,3-thiazane-4-carboxylic acid (6), was synthesized and found to serve as an excellent substrate for Rhesus monkey liver -pipecolate oxidase ( -PO) and also to cause time-dependent, irreversible inactivation of the enzyme. Data are presented demonstrating 6 is a mechanism-based inactivator of L-PO and one of the enzyme turnover products is identified as homocysteine.