Immobilized phenylalanine hydroxylase through the SH groups.
Purified rat liver phenylalanine hydroxylase [L-phenylalanine:tetrahydropteridine:oxygen oxidoreductase (4-hydroxylating), EC 1.14.16.1] was immobilized with activated thiol-Sepharose 4B via disulfide bond formation, which is expected to immobilize the enzyme in its activated form through the SH modification. This immobilized enzyme was more stable against thermal denaturation than the free enzyme. When tetrahydrobiopterin was used as the natural cofactor, the K(m) value for phenylalanine was decreased and that for the cofactor was increased. Constant conversion from phenylalanine to tyrosine was demonstrated continuously for over 8 h at 25 degrees C.
Koizumi
S
S
Laboratory of Cell Physiology, Department of Life Chemistry, Graduate School at Nagatsuta, Tokyo Institute of Technology, Yokohama 227, Japan.
Takeuchi
T
T
Umezawa
H
H
Nagatsu
T
T