Unlike most amino acids, branched-chain amino acids are broken down in tissues other than the liver. Using Table 18.3, identify the three amino acids with branched-chain R groups. For any one of these amino acids, write the equation for its transamination.
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Verified step by step guidance

1. Consult Table 18.3 in your textbook to identify the amino acids with branched-chain R groups. These are amino acids whose side chains (R groups) contain branching, typically involving carbon atoms. The three amino acids with branched-chain R groups are leucine, isoleucine, and valine.
2. Understand the process of transamination. Transamination is a reaction where an amino group (-NH₂) from an amino acid is transferred to an α-keto acid, typically α-ketoglutarate, forming a new amino acid (glutamate) and a new α-keto acid.
3. Choose one of the branched-chain amino acids, such as valine, for the transamination reaction. Write the general equation for transamination: $\mathrm{amino} \mathrm{acid} + \alpha -\mathrm{ketoglutarate} \to \alpha -\mathrm{keto} \mathrm{acid} + \mathrm{glutamate}$
4. For valine, the transamination reaction can be written as: $\mathrm{valine} + \alpha -\mathrm{ketoglutarate} \to \alpha -\mathrm{ketoisovalerate} + \mathrm{glutamate}$
5. Verify the products of the reaction. The α-keto acid formed (α-ketoisovalerate in this case) corresponds to the amino acid's structure with the amino group replaced by a keto group. Glutamate is the other product, formed by the transfer of the amino group to α-ketoglutarate.

Key Concepts

Branched-Chain Amino Acids (BCAAs)

Branched-chain amino acids are a group of three essential amino acids: leucine, isoleucine, and valine. Unlike most amino acids that are metabolized in the liver, BCAAs are primarily broken down in muscle tissues, making them crucial for muscle metabolism and energy production during exercise.

Transamination

Transamination is a biochemical process that involves the transfer of an amino group from one amino acid to a keto acid, forming a new amino acid and a new keto acid. This process is vital for amino acid metabolism and allows the body to synthesize non-essential amino acids from essential ones, facilitating protein synthesis and energy production.

Amino Acid Structure

Amino acids are organic compounds composed of an amino group, a carboxyl group, a hydrogen atom, and a distinctive R group or side chain. The R group determines the specific properties and classification of the amino acid, such as whether it is branched-chain or linear, influencing its role in protein structure and function.