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Brief Overview: Biology of Chalcone and Stilbene Synthase  Products
Chalcone Synthase (CHS)
Stilbene Synthase (STS)                                              
 

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(Last modification: 10. August  2010)

 

The reactions of chalcone (CHS) and stilbene (STS) synthases

    This first page deals with both CHS and STS because they are so similar: both use the same substrates, carry out three condensation reactions, and form a new aromatic ring system. The puzzle for a long time was: what are the mechanisms of the different ring-folding? This will be discussed  in more detail in the stilbene synthase pages: the STS reaction mechanisms.

At the end of the file: structures, trivial and IUPAC names of often mentioned CHS- and STS-products and their derivatives.

 

These links lead to more detailed descriptions

 

Reactions of CHS and STS

The enzymes are about 70% identical.

Reactions of chalcone (CHS) and stilbene (STS) synthases.
A. The common reactions. Both utilize 4-coumaroyl-CoA (or another phenylpropanoid CoA-ester) to perform three condensation reactions with malonyl-CoA. 1, 2, 3 : the three condensation reactions with malonyl-CoA.
B. The folding to different new aromatic ring systems. In contrast to CHS, the terminal carboxyl group is  removed as  CO2  in the STS reaction.

 

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Overview
Backbones and numbering of some molecules derived from chalcone synthase (CHS) and stilbene synthase (STS) reactions, and some often mentioned substances

IUPAC: International Union of Pure and Applied Chemistry which now for more than 90 years (founded in 1919) works at finding a common language in chemistry and biochemistry: more...
Remark: note that the numbering changes from chalcone to flavanone. This easily leads to confusion because the difference is just a ring closure that occurs even non-enzymatically at a fairly high rate: more....

1. CHS

Some links to pages discussing the molecules:
Naringenin chalcone (IUPAC: (E)-3-(4-hydroxyphenyl)-1-(2,4,6-trihydroxyphenyl)prop-2-en-1-one),    
Quercetin (IUPAC: 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one),     
6'-Deoxychalcone (IUPAC: (E)-1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one),     
5-Deoxyflavanone (IUPAC: (2S)-7-hydroxy-2-(4-hydroxyphenyl)-2,3-dihydrochromen-4-one),
Isomerase in conversion of chalcone into flavanone.

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2. STS

The situation is here a bit more complicated, for two reasons: a) the backbones are symmetric and thus the numbering is at the level of the derivatives, and b) various authors, because of the symmetry, used different numbering systems (for example, numbering from 1 to end, not using 1' and so on). I am using here the numbering preferred by Gorham in his book (Gorham, J., 1995. The Biochemistry of the Stilbenoids. Chapman & Hall, London).
Remark: note that the numbering changes from hydrangeic acid to hydrangenol. This easily leads to confusion because the difference is just a ring closure. The 3,4-Dihydro-isocoumarin backbone is marked in blue.

Some links to pages discussing the molecules. Also added are the official IUPAC names:
Resveratrol (IUPAC: 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol),     
Pinosylvin (IUPAC: 5-[(E)-2-phenylethenyl]benzene-1,3-diol),    
Lunularic acid (IUPAC: 2-hydroxy-6-[2-(4-hydroxyphenyl)ethyl]benzoic acid),    
Lunularin (3-[2-(4-hydroxyphenyl)ethyl]phenol),    
Hydrangeic acid (IUPAC: 2-hydroxy-6-[(E)-2-(4-hydroxyphenyl)ethenyl]benzoic acid),    
Hydrangenol (IUPAC: 8-hydroxy-3-(4-hydroxyphenyl)-3,4-dihydroisochromen-1-one),   

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