Metabolism of DL-(+/-)-phenylalanine by Aspergillus niger.
A fungus capable of degrading DL-phenylalanine was isolated from the soil and identified as Aspergillus niger. It was found to metabolize DL-phenylalanine by a new pathway involving 4-hydroxymandelic acid. D-Amino acid oxidase and L-phenylalanine: 2-oxoglutaric acid aminotransferase initiated the degradation of D- and L-phenylalanine, respectively. Both phenylpyruvate oxidase and phenylpyruvate decarboxylase activities could be demonstrated in the cell-free system. Phenylacetate hydroxylase, which required reduced nicotinamide adenine dinucleotide phosphate, converted phenylacetic acid to 2- and 4-hydroxyphenylacetic acid. Although 4-hydroxyphenylacetate was converted to 4-hydroxymandelate, 2-hydroxyphenylacetate was not utilized until the onset of sporulation. During sporulation, it was converted rapidly into homogentisate and oxidized to ring-cleaved products. 4-Hydroxymandelate was degraded to protocatechuate via 4-hydroxybenzoylformate, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate.
D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D001230:Aspergillus / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism; D002474:Cell-Free System; D003605:D-Amino-Acid Oxidase / Q000378:metabolism; D004790:Enzyme Induction; D062385:Hydroxybenzoates / Q000378:metabolism; D008333:Mandelic Acids / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism*; D013237:Stereoisomerism
D062385:Hydroxybenzoates; D008333:Mandelic Acids; D010649:Phenylalanine; D010088:Oxidoreductases; D000445:Aldehyde Oxidoreductases; D003605:D-Amino-Acid Oxidase; D002262:Carboxy-Lyases