Lysine biosynthesis in Rhodotorula glutinis: properties of pipecolic acid oxidase

Abstract

Pipecolic acid oxidase from Rhodotorula glutinis, which converts pipecolic acid to a-aminoadipic-&-semialdehyde, an intermediate of the biosynthetic pathway of lysine, was purified 290-fold. The enzyme from the crude extract and purified preparation exhibited a molecular weight of approximately 43,000 and was composed of a single subunit. The purified enzyme was heat labile and exhibited a pH optimum of 8.5 and an apparent Km for L-pipecolic acid of 1.67 x 10-3 M. L-Proline acted as a competitive inhibitor for the enzyme. The enzyme was inhibited by the sulfhydryl agents p-chloromercuribenzoate and mercuric chloride. The in vitro enzyme activity required oxygen, and upon oxidation of pipecolic acid, oxygen was reduced to hydrogen peroxide.

Lysine biosynthesis and metabolism in fungi

“…83 Following up on this finding, Kinzel and Bhattacharjee reported the purification to near homogeneity and characterization of pipecolic acid oxidase from R. glutinis. 84 The enzyme is a 43 kDa monomer exhibiting optimum activity at pH 8.5 with an apparent K M for l-PA of 1.67 mM. Molecular oxygen is required for activity and H 2 O 2 is produced along with D 1 -P6C.…”

Nitrogen Nutrition and Adaptation of Halophyte Chenopodium quinoa to Salt Stress

“…Moreover, halophytes differ in their resistance to salinity and this is one of the bases used to assess their potential of utilization . The salt concentration leading to the yield depres-sion of 50% relative to its yield under non-saline conditions is defined as the limit of salinity tolerance (Kinzel and Bhattacharjee 1982). Quinoa was classified as a facultative halophyte with an ability to grow under salinity levels similar to those found in seawater, and the limit of salinity resistance (C50 value) for biomass production and seed yield was estimated to be approximately at 20 dSm -1 .…”