A pyridoxal-phosphate protein. L-Phenylalanine can act instead of L-tyrosine. The mitochondrial enzyme may be identical with EC 184.108.40.206 (aspartate transaminase). The three isoenzymic forms are interconverted by EC 220.127.116.11 (stem bromelain) and EC 18.104.22.168 (fruit bromelain). The enzyme can also catalyse the final step in the methionine-salvage pathway of Klebsiella pneumoniae .