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

Verified step by step guidance

1. Step 1: Understand the problem. The task is to draw the condensed structural formula for the dipeptide alanylcysteine, which is formed by linking the amino acids alanine and cysteine. Additionally, provide the three-letter and one-letter abbreviations for this peptide.
2. Step 2: Recall the structure of alanine. Alanine (Ala) is a nonpolar amino acid with the side chain -CH₃. Its general structure is NH₂-CH(CH₃)-COOH.
3. Step 3: Recall the structure of cysteine. Cysteine (Cys) is a polar amino acid with a thiol (-SH) group in its side chain. Its general structure is NH₂-CH(CH₂SH)-COOH.
4. Step 4: Form the peptide bond. A peptide bond is formed between the carboxyl group (-COOH) of alanine and the amino group (-NH₂) of cysteine. This involves the removal of a water molecule (H₂O) during the condensation reaction. The resulting structure will have the following condensed formula: NH₂-CH(CH₃)-CO-NH-CH(CH₂SH)-COOH.
5. Step 5: Provide the abbreviations. The three-letter abbreviation for alanylcysteine is Ala-Cys, and the one-letter abbreviation is AC.

Key Concepts

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.

Amino Acid Abbreviations

Amino acids are the building blocks of peptides and proteins, each having a unique three-letter and one-letter abbreviation. For example, alanine is abbreviated as 'Ala' (three-letter) and 'A' (one-letter), while cysteine is 'Cys' and 'C'. Familiarity with these abbreviations is crucial for efficiently communicating and interpreting peptide sequences.

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, allowing for a quick understanding of the molecule's structure. Mastery of this notation is important for visualizing and analyzing chemical compounds.