The Question is from neet-botany biotechnology genetically-engineered-insulin, and it was created by the author Mr. NARESH KUMAR K

Question

A scientist aims to modify the human insulin gene to increase its binding affinity to the insulin receptor. Which amino acid substitution within the insulin A-chain is MOST likely to achieve this, considering its role in receptor interaction?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Protein-protein interactions and the influence of amino acid side chains on binding affinity.
 **Related Topics**: Insulin structure, insulin receptor binding, hydrophobic interactions, electrostatic interactions, amino acid properties.
 **Prerequisites**: Understanding of protein structure, amino acid properties (hydrophobicity, charge), and the basics of protein-ligand interactions.
## SOLUTION PATHWAY
**Given Information**:
  The goal is to increase the binding affinity of insulin to its receptor by substituting an amino acid in the A-chain.
  Options involve different amino acid substitutions at various positions in the A-chain.
**Method & Steps**:
 1. Analyze the properties of the amino acids involved in each substitution.
  Reasoning:  The interaction between insulin and its receptor involves various forces, including hydrophobic interactions and electrostatic interactions.  Substitutions that enhance these interactions would likely increase binding affinity.
  Formula/Rule: None directly applicable, but understanding of amino acid properties is crucial.
 2. Consider the location of the amino acid substitution within the insulin A-chain.  Amino acids directly involved in receptor contact are more likely to affect binding affinity.
  Working:  Glycine (G) at position A1 is a small, nonpolar amino acid. Glutamic acid (E) is a negatively charged, polar amino acid. This substitution could introduce a new electrostatic interaction with positively charged residues on the receptor, potentially increasing binding affinity.
  Key Point:  The other options involve substitutions that are less likely to dramatically improve binding affinity.  For example, Valine to Leucine is a conservative substitution of hydrophobic amino acids.
 3. Evaluate the potential impact of each substitution on binding affinity.
  Result: The substitution of Glycine at A1 with Glutamic acid (option B) is the most likely to significantly increase binding affinity due to the introduction of a new, potentially favorable electrostatic interaction.
  Verification: This is a reasoned prediction based on the properties of the amino acids and their potential impact on receptor binding. Experimental verification would be required to confirm the effect.
 ## OPTION ANALYSIS
A :x: Valine to Leucine is a conservative substitution; both are hydrophobic, leading to minimal change in binding.
B ✓: Glycine to Glutamic acid introduces a charged residue, potentially creating a favorable electrostatic interaction with the receptor.
C :x: Isoleucine to Valine is a conservative substitution; both are hydrophobic, leading to minimal change in binding.
D :x: Glutamine to Asparagine is a conservative substitution; both are polar, leading to minimal change in binding.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Ignoring the properties of the amino acids involved:  Failing to consider the size, charge, and polarity of amino acids can lead to incorrect predictions.
  2.Assuming all substitutions are equally effective:  Conservative substitutions generally have little effect on protein function or binding.
 **Quick Tips**:
  1.Focus on the differences in properties between the original and substituted amino acids.
  2.Consider the potential for new interactions (electrostatic, hydrophobic) to enhance binding.

Mr. NARESH KUMAR K · Answer

A. Valine at A3 to Leucine

Mr. NARESH KUMAR K · Answer

The correct Option is "B. Glycine at A1 to Glutamic acid"

Mr. NARESH KUMAR K · Answer

C. Isoleucine at A2 to Valine

Mr. NARESH KUMAR K · Answer

D. Glutamine at A5 to Asparagine

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