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Difference between revisions of "Conformational nomenclature"
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* [[Responsible Curator]]: [[User:SpencerWilliams|Spencer Williams]] | * [[Responsible Curator]]: [[User:SpencerWilliams|Spencer Williams]] | ||
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| − | The conformations adopted by a pyranose or furanose ring are denoted by a system in which a capital letter indicates the overall shape, ''C'' = chair, ''B'' = boat, ''H'' = half chair, ''S'' = skew boat, ''E'' = envelope <cite> | + | The conformations adopted by a pyranose or furanose ring are denoted by a system in which a capital letter indicates the overall shape, ''C'' = chair, ''B'' = boat, ''H'' = half chair, ''S'' = skew boat, ''E'' = envelope <cite>IUPACNomenclature1981 IUPACNomenclature1980</cite>. The first four of these conformations has four atoms in a plane; the envelope conformation has five. |
| − | The particular conformation is then denoted by assigning the letter corresponding to the shape (''C'', ''B'', ''H'', ''S'', ''E''); determining the four (or five) atoms that define the plane; assigning a 'top' and 'bottom' face through the use of a left-hand rule counting in the order of increasing ring carbon; and then indicating the identities and relative positions (top face = superscript and prefix; bottom face = subscript and suffix) of the remaining two atoms on that capital letter. In the case of the envelope conformation, only a single atom is located outside of the plane. For a more detailed discussion see the excellent book by J. Fraser Stoddard <cite> | + | The particular conformation is then denoted by assigning the letter corresponding to the shape (''C'', ''B'', ''H'', ''S'', ''E''); determining the four (or five) atoms that define the plane; assigning a 'top' and 'bottom' face through the use of a left-hand rule counting in the order of increasing ring carbon; and then indicating the identities and relative positions (top face = superscript and prefix; bottom face = subscript and suffix) of the remaining two atoms on that capital letter. In the case of the envelope conformation, only a single atom is located outside of the plane. For a more detailed discussion see the excellent book by J. Fraser Stoddard <cite>Stoddart1971</cite>. |
| − | [[Image:Conformations.png|centre| | + | It should be noted that the conformational symbols for enantiomers are different. This is because the reference plane is the same, yet application of the left-hand rule results in a different 'top' and 'bottom' face. Thus the mirror image of α-D-glucose-<sup>4</sup>''C<sub>1</sub> is α-L-glucose-<sup>1</sup>''C<sub>4</sub>. It is therefore important to state whether the D or L form is under consideration. |
| + | |||
| + | [[Image:Conformations.png|centre|800px]] | ||
==References== | ==References== | ||
<biblio> | <biblio> | ||
| − | # | + | #IUPACNomenclature1981 Conformational nomenclature for five- and six-membered ring forms of monosaccharides and their derivatives, Pure and Appl. Chem., 1981, ''53'', 1901—1905. [http://dx.doi.org/10.1351/pac198153101901 DOI: 10.1351/pac198153101901] |
| − | # | + | #IUPACNomenclature1980 pmid=7460897 |
| + | #Stoddart1971 Stereochemistry of Carbohydrates, J. Fraser Stoddart, John Wiley & Sons Inc, 1971, 264 pages. | ||
</biblio> | </biblio> | ||
[[Category:Definitions and explanations]] | [[Category:Definitions and explanations]] | ||
Latest revision as of 02:56, 30 October 2024
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The conformations adopted by a pyranose or furanose ring are denoted by a system in which a capital letter indicates the overall shape, C = chair, B = boat, H = half chair, S = skew boat, E = envelope [1, 2]. The first four of these conformations has four atoms in a plane; the envelope conformation has five.
The particular conformation is then denoted by assigning the letter corresponding to the shape (C, B, H, S, E); determining the four (or five) atoms that define the plane; assigning a 'top' and 'bottom' face through the use of a left-hand rule counting in the order of increasing ring carbon; and then indicating the identities and relative positions (top face = superscript and prefix; bottom face = subscript and suffix) of the remaining two atoms on that capital letter. In the case of the envelope conformation, only a single atom is located outside of the plane. For a more detailed discussion see the excellent book by J. Fraser Stoddard [3].
It should be noted that the conformational symbols for enantiomers are different. This is because the reference plane is the same, yet application of the left-hand rule results in a different 'top' and 'bottom' face. Thus the mirror image of α-D-glucose-4C1 is α-L-glucose-1C4. It is therefore important to state whether the D or L form is under consideration.
References
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Conformational nomenclature for five- and six-membered ring forms of monosaccharides and their derivatives, Pure and Appl. Chem., 1981, 53, 1901—1905. DOI: 10.1351/pac198153101901
- (1980). IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN). Conformational nomenclature for five and six-membered ring forms of monosaccharides and their derivatives: recommendations 1980. Eur J Biochem. 1980;111(2):295-8. DOI:10.1111/j.1432-1033.1980.tb04941.x |
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Stereochemistry of Carbohydrates, J. Fraser Stoddart, John Wiley & Sons Inc, 1971, 264 pages.