Publications

• Purification and characterization of S-adenosyl-L-methionine: norcoclaurine 6-O-methyltransferase from cultured Coptis japonica cells.

  Sato F., Tsujita T., Katagiri Y., Yoshida S., Yamada Y.

  S-adenosyl-L-methionine:norcoclaurine 6-O-methyltransferase (norcoclaurine 6-O-methyltransferase), which catalyzes the transfer of the S-methyl group of S-adenosyl-L-methionine to the 6-hydroxyl group of 1,2,3,4-tetrahydro-1-[(4-hydroxyphenyl)methyl]-6,7-isoquinolinediol (norcoclaurine), was purif ... >> More

  S-adenosyl-L-methionine:norcoclaurine 6-O-methyltransferase (norcoclaurine 6-O-methyltransferase), which catalyzes the transfer of the S-methyl group of S-adenosyl-L-methionine to the 6-hydroxyl group of 1,2,3,4-tetrahydro-1-[(4-hydroxyphenyl)methyl]-6,7-isoquinolinediol (norcoclaurine), was purified from cultured Coptis japonica cells and its enzymic properties were characterized. Purified norcoclaurine 6-O-methyltransferase had apparent pI 4.7, a native molecular mass of 95 kDa (determined by gel filtration) and subunit molecular mass of 40 kDa (SDS/PAGE). The enzyme did not require a divalent cation for activity, and the addition of Fe2+, Cu2+, Co2+, Zn2+, Mn2+, or Ni2+ at 5 mM severely inhibited enzyme activity. Neither p-chloromercuribenzoate, N-methylmaleimide nor iodoacetamide inhibited enzyme activity at 1 mM. 5,6-Dihydro-9,10-dimethoxybenzo[g]-1,3-benzodioxolo[5,6-a]qu inolizinium (berberine, the end-product of the biosynthetic pathway in which norcoclurine 6-O-methyltransferase catalyzes an intermediate step) also inhibited the activity by 50% at 10 mM. Norcoclaurine 6-O-methyltransferase methylated both (S)-norcoclaurine and (R)-norcoclaurine and (R,S)-norlaudanosoline. Further characterization of substrate-saturation kinetics and product inhibition of the purified enzyme indicated that norcoclaurine 6-O-methyltransferase follows a bi-bi ping-pong mechanism with Km values of 2.23 mM and 3.95 mM for (R,S)-norlaudanosoline and S-adenosyl-L-methionine, respectively, while Ki values for S-adenosylhomocysteine versus S-adenosyl-L-methionine and (R,S)-norlaudanosoline were 2.1 mM and 0.18 mM, respectively. << Less

  Eur. J. Biochem. 225:125-131(1994) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Partial Purification and Properties of S-Adenosylmethionine: (R), (S)-Norlaudanosoline-6-O-Methyltransferase from Argemone platyceras Cell Cultures.

  Rueffer M., Nagakura N., Zenk M.H.

  A new enzyme, S-adenosylmethionine: (R), (S)-norlaudanosoline-6-O-methyltransferase, was isolated from the soluble protein extract of A. PLATYCERAS cell cultures and purified approximately 80-fold. This enzyme catalyses the formation of 6-O-methylnorlaudanosoline, and, to a minor extent, 7-O-methy ... >> More

  A new enzyme, S-adenosylmethionine: (R), (S)-norlaudanosoline-6-O-methyltransferase, was isolated from the soluble protein extract of A. PLATYCERAS cell cultures and purified approximately 80-fold. This enzyme catalyses the formation of 6-O-methylnorlaudanosoline, and, to a minor extent, 7-O-methylnorlaudanosoline from SAM and (S), as well as (R), norlaudanosoline. The apparent molcular weight of the enzyme is 47000 Dalton. The pH-optimum of the enzyme is 7.5, the temperature optimum, 35 degrees C. Apparent K (M) values for (S) and (R)-norlaudanosoline were 0.2 mM, and for SAM, 0.05 mM. The transferase shows high substrate specificity for tetrahydrobenzylisoquinoline alkaloids. Simple orthophenols, like phenylpropane derivatives, coumarins or flavonoids, are not accepted as substrates. The enzyme is widely distributed in benzylisoquinoline-containing plant cell cultures and is present in differentiated plants like PAPAVER SOMNIFERUM. << Less

  Planta Med 49:131-137(1983) [PubMed] [EuropePMC]