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Ch.16 Amino Acids, Proteins, and Enzymes
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 16, Problem 12b

Draw the condensed structural formula for each of the following peptides, and give its three-letter and one-letter abbreviations:
b. threonylleucine

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1
Step 1: Understand the problem. The task is to draw the condensed structural formula for the dipeptide threonylleucine, which consists of two amino acids: threonine (Thr) and leucine (Leu). Additionally, provide the three-letter and one-letter abbreviations for the peptide.
Step 2: Recall the structure of threonine (Thr). Threonine is an amino acid with the side chain -CH(OH)CH3. Its general structure includes an amino group (-NH2), a carboxyl group (-COOH), and the side chain attached to the alpha carbon.
Step 3: Recall the structure of leucine (Leu). Leucine is an amino acid with the side chain -CH2CH(CH3)2. Like threonine, it has an amino group, a carboxyl group, and the side chain attached to the alpha carbon.
Step 4: Form the peptide bond. When threonine and leucine combine to form threonylleucine, the carboxyl group (-COOH) of threonine reacts with the amino group (-NH2) of leucine. This reaction releases a molecule of water (H2O) and forms a peptide bond (-CONH-).
Step 5: Write the condensed structural formula. Combine the structures of threonine and leucine, connected by the peptide bond. The condensed structural formula will look like this: Thr-Leu. For the abbreviations, the three-letter abbreviation is 'Thr-Leu,' and the one-letter abbreviation is 'T-L.'

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Peptide Structure

Peptides are short chains of amino acids linked by peptide bonds. The structure of a peptide is determined by the sequence of its constituent amino acids, which influences its properties and functions. Understanding how to represent peptides structurally, including their condensed formulas, is essential for biochemistry and molecular biology.
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Amino Acid Abbreviations

Amino acids are the building blocks of peptides and proteins, each represented by a unique three-letter and one-letter abbreviation. For example, threonine is abbreviated as 'Thr' (three-letter) and 'T' (one-letter), while leucine is 'Leu' and 'L'. Familiarity with these abbreviations is crucial for efficiently communicating and understanding protein sequences.
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Condensed Structural Formula

A condensed structural formula provides a simplified representation of a molecule, showing the arrangement of atoms without depicting all bonds explicitly. In the context of peptides, it illustrates how amino acids are connected in a sequence. Mastery of drawing condensed structural formulas is important for visualizing molecular structures and understanding their chemical properties.
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