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Updated: Jul 15, 2026

High-Throughput Metabolic Profiling for Model Refinements of Microalgae
Published on: December 4, 2021
Alanine racemase from the green alga Chlamydomonas reinhardtii
K Nishimura1, Y Tomoda, Y Nakamoto
1Department of Applied Chemistry, Junior College, Nihon University, Chiba, Japan. nisimura@chem.cst.nihon-u.ac.jp
Abstract:
Chlamydomonas reinhardtii, a unicellular green microalga, could grow to a stationary phase having optical density of 2.0-2.5 at 750 nm in Tris-acetate-phosphate (TAP) medium containing 0.1% D-alanine. D-alanine has no inhibitory effect on growth and induced alanine racemase activity 130-fold more than without D-alanine in the green alga. Although C. reinhardtii cultured in the TAP medium showed alanine racemase activity, the content of free D-alanine was only 0.14%. The enzyme was partially purified by ammonium sulfate fractionation followed by three kinds of liquid chromatography using DEAE Toyopearl, Phenyl Sepharose, and TSK G3000 SWXL columns. The specific activity for L-alanine of the partially purified alanine racemase was 3.8 micromol/min/mg. The molecular weight of the enzyme was determined to be approximately 72,000 by gel filtration. The enzyme showed a maximum activity at 45 degrees C and pH 8.4 and requires pyridoxal 5'-phosphate as a coenzyme.
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