Dipeptide Gly-Ala Structure Explanation
A dipeptide is formed when two amino acids join via a peptide bond. The notation Gly-Ala (glycyl alanine) indicates that Glycine (Gly) is the first amino acid (N-terminus) and Alanine (Ala) is the second amino acid (C-terminus).
Amino Acid Components
- Glycine (Gly): The simplest amino acid, with the structure $H_2N-CH_2-COOH$.
- Alanine (Ala): An amino acid with a methyl side chain, structure $H_2N-CH(CH_3)-COOH$.
Peptide Bond Formation
The peptide bond forms between the carboxyl group ($-COOH$) of the first amino acid (Glycine) and the amino group ($H_2N-$) of the second amino acid (Alanine), releasing a molecule of water ($H_2O$).
The reaction is:
$ H_2N-CH_2-COOH \quad \text{(Glycine)} \quad + \quad H_2N-CH(CH_3)-COOH \quad \text{(Alanine)} \quad \rightarrow \quad H_2N-CH_2-CO-NH-CH(CH_3)-COOH \quad \text{(Gly-Ala)} \quad + \quad H_2O $Structure Analysis of Gly-Ala
The resulting dipeptide, Gly-Ala, has the following structure:
- The free amino group ($H_2N-$) at the beginning belongs to Glycine (N-terminus).
- The peptide bond ($-CO-NH-$) links Glycine's carbonyl carbon to Alanine's amino nitrogen.
- The free carboxyl group ($-COOH$) at the end belongs to Alanine (C-terminus).
This structure matches Option 1.
Correct Option Identification
Comparing the derived structure with the given options:
- Option 1: $H_2N-CH_2– CO – NH – CH(CH_3) – COOH$ - Matches the structure of Gly-Ala.
- Options 2, 3, and 4 represent different arrangements or incorrect peptide bond formations (e.g., Ala-Gly or incorrect termini).
Therefore, the correct structure of Gly-Ala is provided in Option 1.
Important Questions from Biomolecules
The chemical name of Vitamin D 3is:
Which of the following food comes under complex carbohydrate?
I. Potatoes
II. Sweets
III. Pasta
IV. Wheat
Following are the pKa's of the ionizable groups in lysine
pKa 1 = 2.16 (α - carboxylic group)
pKa 2 = 9.06 (α - amino group)
pKa 3 = 10.54 (ε - amino group)
Which one of the following options represents the pl of lysine?
How many hydrogen bonds involving the backbone CO and NH can be observed in an α‐helix consisting of 15 amino acid residues?
In eukaryotic cells, covalently attached lipids help to anchor some water soluble proteins to the plasma membrane. One group of cytosolic proteins are anchored to the cytosolic face of membrane by a fatty acyl group (e.g. myristate or palmitate). These groups are generally covalently attached to which amino acids present at the N‐terminus of the polypeptide chain?
