2.6.1.38 0.0015 - substrate L-tryptophan 639972 2.6.1.38 0.0019 - substrate L-histidine 639972 2.6.1.38 0.002 - substrate L-tyrosine 639972 2.6.1.38 0.0021 - substrate L-phenylalanine 639972 2.6.1.38 0.866 - - 639973 2.6.1.38 17.8 - - 639970