Catalyzes the interconversion of L-alanine and D-alanine. Does not act on other amino acids. L-alanine = D-alanine Optimum pH is 8-10. Highly active at low temperatures, even at 0 degree Celsius. Thermolabile. Amino-acid biosynthesis; D-alanine biosynthesis; D-alanine from L-alanine: step 1/1. Homodimer. Belongs to the alanine racemase family.