the pool of phenylalanine , tyrosine , and tryptophan is formed in escherichia coli k-12 by a general aromatic transport system [ michaelis constant ( k ( m ) ) for each amino acid approximately 5 x 10 ( -7 ) m ] and three further transport systems each specific for a single aromatic amino acid ( k ( m ) for each amino acid approximately 2 x 10 ( -6 ) m , reference 3 ) .
C0041249
tryptophan
C0301713
aromatic amino acid