# DBT JRF 2022 — Question 130

Exam: DBT JRF 2022 · Section: B · Topic: Biochemistry › Protein Hydrophobicity & Protein Interactions · Difficulty: Medium

## Question

Proteins usually have hydrophobic interiors or cores and hydrophilic exteriors. If a protein comprises hydrophobic patches on its outer surface, what can it mean?

## Options

- **A.** The protein is unstable
- **B.** Structure prediction was done wrongly
- **C.** It could be part of a multimeric protein complex
- **D.** It is a DNA-binding protein

## Answer

Option C

## Explanation

Hydrophobic patches on protein surface — multimeric complex: The hydrophobic effect is a major driver of protein folding: • Hydrophobic residues (Leu, Ile, Val, Phe, Met) are energetically unfavourable when exposed to aqueous solvent. • Proper protein folding buries hydrophobic residues in the core, away from water. • Well-folded, stable monomeric proteins have hydrophilic surfaces (polar/charged residues) facing water. If a protein shows hydrophobic PATCHES on its outer surface: • These patches represent protein-protein INTERFACE sites. • In a multimeric complex, a hydrophobic patch on one subunit packs against the complementary hydrophobic patch on a partner subunit → both patches are buried from solvent. • This is thermodynamically favourable (reduces hydrophobic surface area exposed to water). Diagnosis: • Hydrophobic patches ≠ misfolded protein (that would be unstable, but the question says it's a valid structure) • Hydrophobic patches ≠ DNA-binding protein (those tend to have positively charged basic regions) Answer: Surface hydrophobic patches indicate the protein forms part of a multimeric complex, with patches forming subunit-subunit interfaces.

Source: https://mypyqbuddy.com/questions/proteins-usually-have-hydrophobic-interiors-or-cores-and-6a104cd5920734408bc0c791