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When oxaloacetic acid and acetyl-coenzyme A (acetyl-CoA) labeled with
Chapter 3, Problem 3.24(choose chapter or problem)
When oxaloacetic acid and acetyl-coenzyme A (acetyl-CoA) labeled with radioactivecarbon-14 in position 2 are incubated with citrate synthase, an enzyme of the tricarbox-ylic acid cycle, only the following enantiomer of [2-14C]citric acid is formed stereoselec-tively. Note that citric acid containing only 12C is achiral. Assign an R or S configurationto this enantiomer of [2-14C]citric acid. (Note: Carbon-14 has a higher priority thancarbon-12.)
Questions & Answers
QUESTION:
When oxaloacetic acid and acetyl-coenzyme A (acetyl-CoA) labeled with radioactivecarbon-14 in position 2 are incubated with citrate synthase, an enzyme of the tricarbox-ylic acid cycle, only the following enantiomer of [2-14C]citric acid is formed stereoselec-tively. Note that citric acid containing only 12C is achiral. Assign an R or S configurationto this enantiomer of [2-14C]citric acid. (Note: Carbon-14 has a higher priority thancarbon-12.)
ANSWER:Key concepts
R and S configuration
In organic chemistry, R and S configurations are terms used to describe the stereochemistry of a molecule. Stereochemistry is the study of the three-dimensional arrangement of atoms in a molecule and the effect it has on their physical and chemical properties.
The R and S configuration is a system for naming the stereoisomers of a molecule. This system is based on the Cahn-Ingold-Prelog (CIP) priority rules, which determine the priority of substituents attached to a chiral center (a carbon atom bonded to four different substituents).
1. R Configuration: In this configuration, the molecule has the highest priority substituent pointing away from the observer.
2. S Configuration: In this configuration, the molecule has the highest priority substituent pointing towards the observer.
Step 1 of 2
The reaction is
We need to assign R and S configuration for the product.
The structure has one chiral center, and it is indicated with a red color asterisk symbol.