Isolation and purification of tyrosine hydroxylase from callus cultures of Portulaca grandiflora.
Tyrosine hydroxylase was separated from polyphenol oxidase activity and was highly purified from betacyanin producing callus cultures of Portulaca grandiflora. The purified enzyme catalyzed the formation of DOPA (L-3,4-dihydroxyphenylalanine) from tyrosine and required the pterin compounds (6-methyl-5,6,7,8-tetrahydropterin; 5,6,7,8-tetrahydrobiopterin; 6,7-dimethyl-5,6,7,8-tetrahydropterin) as coenzyme. The K(m) values for tyrosine and 6-methyl-5,6,7,8-tetrahydropterin were 0.5 mM and 0.15 mM, respectively. This enzyme was activated by Fe(2+) and Mn(2+), and inhibited by metal chelating agents.
Yamamoto Ki
Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto, 860-8555 Japan.
Kobayashi
N
N
Yoshitama
K
K
Teramoto
S
S
Komamine
A
A
D002384:Catalysis; D004156:Catechol Oxidase / Q000737:chemistry / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D003067:Coenzymes / Q000494:pharmacology; D046508:Culture Techniques; D004295:Dihydroxyphenylalanine / Q000096:biosynthesis; D007501:Iron / Q000494:pharmacology; D007700:Kinetics; D019684:Magnoliopsida / Q000737:chemistry / Q000201:enzymology*; D008345:Manganese / Q000494:pharmacology; D011622:Pterins / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
D002614:Chelating Agents; D003067:Coenzymes; D011622:Pterins; D014443:Tyrosine; D008345:Manganese; D004295:Dihydroxyphenylalanine; D007501:Iron; D004156:Catechol Oxidase; D014446:Tyrosine 3-Monooxygenase