How can I draw the structures of the two enantiomers of cysteine?
The easiest way is to draw them first as Fischer projections.
The general formula for an amino acid is RCH(NH₂)COOH. In cysteine, R = CH₂SH.
You draw the Fischer projection for an amino acid in the same way as for a carbohydrate.
The main chain is vertical, with C-1 at the top. If the NH₂ group is on the left, you have an L-amino acid. If the NH₂ group is on the right, you have an R-amino acid.
Once you have the Fischer projections, you can turn them on their side and convert them into wedge-dash formulas.
If you draw the NH₂-C-COOH bonds in the plane of the paper, with NH₂ on the left and the "V" pointing down, the L-amino acid has the bond to the R group as a dashed line.
If the "V" points up, the L-amino acid has the bond to the R group as a wedge.
So the two structures of cysteine are those above, with R = CH₂SH.
Note that L-cysteine has the (R) configuration. In contrast, L-serine has the (S) configuration.
By signing up, you agree to our Terms of Service and Privacy Policy
To draw the structures of the two enantiomers of cysteine, start with the chemical structure of cysteine and then assign the stereochemistry of the chiral center (the alpha carbon). You'll need to depict the arrangement of the substituents (amino group, carboxyl group, hydrogen, and R-group) around the chiral center to represent each enantiomer.
By signing up, you agree to our Terms of Service and Privacy Policy
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
- How does chirality effect nmr?
- What is a meso compound?
- Addition of water to an alkyne gives a keto-enol tautomer product. What will be the enol that is in equilibrium with the given ketone 2-Pentanone?
- What are the different types of optical isomers seen in coordination compounds? How do you draw optical isomers of coordination compounds?
- Why do enantiomers rotate light?

- 98% accuracy study help
- Covers math, physics, chemistry, biology, and more
- Step-by-step, in-depth guides
- Readily available 24/7