What is the Difference Between L-leucine and Leucine

The key difference between L-leucine and leucine is that L-leucine is the L isomer of the leucine amino acid, whereas leucine is an amino acid that is useful in the biosynthesis of proteins.

There are two major isomeric forms of leucine amino acid: L isomer and D isomer. L isomer of leucine is the most common and abundant leucine isomer having many important uses in the human body.  The protein-rich food we consume also contains L leucine. However, D isomer is less common and less studied.

CONTENTS

1. Overview and Key Difference
2. What is L-leucine  
3. What is Leucine
4. L-leucine vs Leucine in Tabular Form
5. Summary – L-leucine vs Leucine 

What is L-leucine?

L-leucine is the L isomer of leucine amino acid. It is an essential amino acid. It is a primary branched-chain amino acid. This amino acid tends to play a variety of roles in our body and is practically present in every cell of our body. This is because this amino acid is a key component in every mitochondrion. L-leucine is involved in the regulation of blood sugar and energy levels. It is crucial for the growth and repairing of bones and muscles. Further, L-leucine is important for the healing of wounds and is a key ingredient in producing growth hormones.

There can be deficiencies of L-leucine, which leads to symptoms associated with hypoglycemia. Some of those symptoms include fatigue, dizziness, and headache.

We can find L-leucine amino acids present in all the protein-rich food items. Therefore, a person having a balanced diet can get the necessary amount of L-leucine on a daily basis. There are some food items that are rich in L-leucine, such as whey protein, soy protein, soybeans, beef, peanuts and some fish.

What is Leucine?

Leucine is an amino acid that is useful in the biosynthesis of proteins. We can abbreviate its name as Leu or L. It is an essential alpha-amino acid because it contains an alpha-amino acid group, an alpha carboxylic acid group, and a side chain isobutyl group that makes it a nonpolar aliphatic amino acid. Moreover, this is an essential amino acid in humans, and our bodies can’t synthesize it. Therefore, we need to take it from the diet. Meat, dairy products, soy proteins, and beans mainly contain leucine. The codons that encode leucine include UUA, UUG, CUU, CUC, CUA, and CUG.

This amino acid is useful as a food additive where it has the E number E641. We can classify it as a flavour enhancer. In the form of a dietary supplement, leucine can slow down the degradation of muscle tissue by increasing the synthesis of muscle proteins in aged rats, according to some research studies. But the long-term intake of leucine has not increased muscle mass or strength in healthy elderly men.

What is the Difference Between L-leucine and Leucine?

There are two major isomers of leucine as L isomer and D isomer. D isomer is less common and less abundant. L isomer is the common isomeric form of leucine amino acid. The key difference between L-leucine and leucine is that L-leucine is the L isomer of the leucine amino acid, whereas leucine is an amino acid that is useful in the biosynthesis of proteins.

The following infographic lists the differences between L-leucine and leucine in tabular form for side by side comparison.

Summary – L-leucine vs Leucine

L-leucine is the L isomer of leucine amino acid. Leucine is an amino acid that is useful in the biosynthesis of proteins. The key difference between L-leucine and leucine is that L-leucine is the L isomer of the leucine amino acid, whereas leucine is an amino acid that is useful in the biosynthesis of proteins.