In vitro: |
J Biol Chem. 2009 Sep 25;284(39):26758-67. | Removal of substrate inhibition and increase in maximal velocity in the short chain dehydrogenase/reductase salutaridine reductase involved in morphine biosynthesis.[Pubmed: 19648114] | METHODS AND RESULTS:
Sinoacutine reductase (SalR, EC 1.1.1.248) catalyzes the stereospecific reduction of Sinoacutine to 7(S)-salutaridinol in the biosynthesis of morphine. In addition, a specific role in Sinoacutine binding by either hydrogen bond formation or hydrophobic interactions was assigned to each amino acid. Substrate docking also revealed an alternative mode for Sinoacutine binding, which could explain the strong substrate inhibition of Sinoacutine reductase. An alternate arrangement of Sinoacutine in the enzyme was corroborated by the effect of various amino acid substitutions on substrate inhibition. In most cases, the complete removal of substrate inhibition was accompanied by a substantial loss in enzyme activity. However, some mutations greatly reduced substrate inhibition while maintaining or even increasing the maximal velocity.
CONCLUSIONS:
Based on these results, a double mutant of Sinoacutine reductase was created that exhibited the complete absence of substrate inhibition and higher activity compared with wild-type Sinoacutine reductase. | J Nat Prod. 2005 Jul;68(7):1128-30. | Morphinane alkaloids with cell protective effects from Sinomenium acutum.[Pubmed: 16038566 ] | METHODS AND RESULTS:
One new morphinane alkaloid, sinomenine N-oxide (1), and one new natural occurring morphinane alkaloid, N-demethylsinomenine (2), together with six known alkaloids, 7,8-didehydro-4-hydroxy-3,7-dimethoxymorphinan-6-ol (3), sinomenine (4), Sinoacutine (5), N-norSinoacutine, acutumine, and acutumidine, were isolated from the stems of Sinomenium acutum. Their structures were elucidated on the basis of spectroscopic analysis and chemical methods.
CONCLUSIONS:
Compounds 2, 3, and 5 have protective effects against hydrogen peroxide-induced cell injury. |
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