SIMULTANEOUS PURIFICATION AND PROPERTIES OF DEHYDROPEPTIDASE-I AND AMINOPEPTIDASE-M FROM RAT-KIDNEY

  • 1 January 1985
    • journal article
    • research article
    • Vol. 49  (3) , 435-445
Abstract
Two peptidases, dehydropeptidase-I and aminopeptidase-M were solubilized from rat kidney microsomes by treatment with papain and separated by DE-52 ion exchange chromatography. Each enzyme was further purified by Sephacryl S-300 gel filtration and affinity chromatography on Con-A Sepharose. Purified dehydropeptidase-I and aminopeptidase-M were homogeneous by SDS-polyacrylamide gel electrophoresis, and their molecular weights were estimated by gel filtration to be 148,000 and 240,000, respectively; both being homodimer, with a 78,000 subunit for the former and a 120,000 subunit for the latter. Both dehydropeptidase-I and aminopeptidase-M were capable of hydrolyzing L-leucyl-L-leucine with a Km value of 1.1 mM and 1.7 mM, respectively, although the hydrolyzing activity of aminopeptidase-M was much higher than that of dehydropeptidase-I. Aminopeptidase-M was inhibited by bestatin, and dehydropeptidase-I was significantly inhibited by cilastatin. Dehydropeptidase-I catalyzed the conversion of leukotriene D4 to E4 and the hydrolysis of L-cystinyl-bis-glycine, but aminopeptidase-M did not to any appreciable extent. The physiological significance of dehydropeptidase-I was pointed out and discussed.

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