Norlaudanosoline Synthase

1 Norlaudanosoline Synthase. — Strong evidence, including some 

Section 3.1). New evidence from another reputable group of 

An enzyme that synthesises norlaudanosoline (25) has been isolated, and purified, from several plant species which normally produce isoquinoline alkaloids. Substrates for the enzyme were dopamine (21) and, most surprisingly, 3,4-dihydroxyphenylacet-aldehyde (23), and not 3,4-dihydroxyphenylpyruvic acid (22). 4-Hydroxyphenylacetaldehyde was a substrate for the enzyme but not 4-hydroxyphenylpyruvic acid or phenylpyruvic acid. The product of the clearly enzyme-catalysed reaction between (21) and (23) was norlaudanosoline (25) [predominantly the (S)-isomer]. No doubt 

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RUEFFER, M., EL-SHAGI, H., NAGAHURA, N ZENK, M.H., (S)-Norlaudanosoline synthase The first enzyme in the benzylisoquinoline biosynthetic pathway. FEBSLett., 1981,129, 5-9. 

SCHUMACHER, H.-M., RUFFER, M., NAGAKURA, N ZENK, M.H., Partial purification and properties of (5)-norlaudanosoline synthase from Eschscholtzia tenuifolia cell cultures. Planta Med., 1983, 48,212-220. 

As another example of the value of enzymological studies, the major enzymes of the benzylisoquinoline alkaloid pathway have also been isolated from plant tissue culture and studied by Zenk and co-workers (see Chapter 34) (Fig. 1.2). An enzyme, (S)-norlaudanosoline synthase, which catalyzes the conversion of dopamine and (3,4-dihydroxyphen-yl)acetaldehyde (9) into (S)-norlaudanosoline (10) has been purified about 40-fold from cell suspension cultures of Eschscholtzia tenuifolia (see also cluster 32 for up-dated in-... 

Recently, Zenk et al. proved by the discovery of a novel enzyme named norlaudanosoline synthase that route I is a real pathway of benzylisoquinoline biosynthesis, and that the previously postulated intermediate norlaudanosoline-1-carboxylic acid is probably an artefact (Schumacher et al. 1983)... 

Enzymatic Formation of Tetrahydrobenzylisoquinoline Alkaloids 2.1 (S)-Norlaudanosoline Synthase... 

Fig. 1. Scheme of reaction catalysed by (S)-norlaudanosoline synthase indicating also the assay principle... 

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