Table 3.

Immunoprecipitation of PhhA activity by anti-PhhB antibody in the presence of PhhBa

AntibodybSp actcRelative activityd
Preimmune serum54.8 ± 1.9100
Anti-PhhA serum12.2 ± 0.6* 22.3
Anti-PhhB serum14.9 ± 0.6* 27.3
  • a E. coli (pJZ9-3a) crude extract containing both PhhA and PhhB was used as the enzyme source in the assay.

  • b Rabbit antisera against PhhA and PhhB and preimmune serum (control) were used.

  • c The specific activity of phenylalanine hydroxylase is defined as nanomoles of tyrosine formed per minute per milligram of protein and is expressed as a mean value ± the standard deviation. *, significantly different from the value for the preimmune control (P < 0.001).

  • d Relative activity is expressed as a percentage of the activity of the control (preimmune serum).