Skip to main content
Ch. 24 - Amino Acids, Peptides, and Proteins
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Non è quello che usi tu?Cambia libro di testo
Capitolo 24, Problema 4a

Draw the structure of the predominant form of
(a) isoleucine at pH 11.

Guida verificata passo dopo passo
1
Step 1: Understand the structure of isoleucine. Isoleucine is an amino acid with the following functional groups: an amino group (-NH₂), a carboxylic acid group (-COOH), and a side chain containing a hydrocarbon group. Its molecular formula is C₆H₁₃NO₂.
Step 2: Recall the pH-dependent behavior of amino acids. At pH 11, the environment is basic, meaning the amino acid will lose protons from its acidic functional groups. Specifically, the carboxylic acid group (-COOH) will deprotonate to form a carboxylate ion (-COO⁻), and the amino group (-NH₂) will remain unprotonated as -NH₂.
Step 3: Identify the predominant form of isoleucine at pH 11. The carboxylic acid group will exist as -COO⁻, and the amino group will remain as -NH₂. The side chain does not have ionizable groups, so it remains unchanged.
Step 4: Draw the structure of isoleucine at pH 11. Represent the backbone with the amino group (-NH₂) on one end, the carboxylate group (-COO⁻) on the other end, and the side chain attached to the central carbon atom. Ensure the stereochemistry of isoleucine is correct, as it is a chiral molecule.
Step 5: Verify the structure. Double-check that the functional groups are correctly represented for the basic pH environment and that the stereochemistry of the molecule is accurate.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
5m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Amino Acid Structure

Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group). The structure of isoleucine, an essential amino acid, includes a branched-chain aliphatic side group, which influences its properties and behavior in biological systems.
Video consigliato:
7:19
Charged Amino Acids

pH and Ionization

pH is a measure of the acidity or basicity of a solution, affecting the ionization state of functional groups in molecules. At higher pH levels, such as pH 11, amino acids tend to lose protons from their carboxyl groups and may also affect the amino group. Understanding how pH influences the ionization of amino acids is crucial for predicting their predominant forms in different environments.
Video consigliato:
04:28
Ionization Potentials

Zwitterion Formation

A zwitterion is a molecule that has both positive and negative charges but is overall neutral. In the case of amino acids, at physiological pH, they often exist as zwitterions, where the amino group is protonated (-NH3+) and the carboxyl group is deprotonated (-COO-). At pH 11, isoleucine will predominantly exist in a deprotonated form, affecting its solubility and reactivity in biological systems.
Video consigliato:
04:41
Why Amino Acids Exist as Zwitterions
Pratica correlata
Domanda del libro di testo

Draw the structure of the predominant form of

(e) a mixture of alanine, lysine, and aspartic acid at (iii) pH 2.

800
views
Domanda del libro di testo

Most naturally occurring amino acids have chiral centers (the asymmetric α carbon atoms) that are named (S) by the Cahn–Ingold–Prelog convention (Section 5-3). The common naturally occurring form of cysteine has a chiral center that is named (R), however.

(a) What is the relationship between (R)-cysteine and (S)-alanine? Do they have the opposite three-dimensional configuration (as the names might suggest) or the same configuration?

1368
views
Domanda del libro di testo

The herbicide glyphosate (Roundup®) kills plants by inhibiting an enzyme needed for synthesis of phenylalanine. Deprived of phenylalanine, the plant cannot make the proteins it needs, and it gradually weakens and dies. Although a small amount of glyphosate is deadly to a plant, its human toxicity is quite low. Suggest why this powerful herbicide has little effect on humans.

1969
views
Domanda del libro di testo

Draw the structure of the predominant form of

(d) glutamic acid at pH 7.

1351
views
Domanda del libro di testo

Draw the structure of the predominant form of

(b) proline at pH 2.

1719
views
Domanda del libro di testo

Most naturally occurring amino acids have chiral centers (the asymmetric α carbon atoms) that are named (S) by the Cahn–Ingold–Prelog convention (Section 5-3). The common naturally occurring form of cysteine has a chiral center that is named (R), however.

(b) (S)-Alanine is an L-amino acid (Figure 24-2). Is (R)-cysteine a d-amino acid or an L-amino acid?

731
views