How many of the given compounds will give a positive Biuret test ____ ? Glycine, Glycylalanine, Trip — Biomolecules Chemistry Question

💡 Solution & Explanation

**Step 1: Understand the Biuret test requirement** The Biuret test detects compounds with two or more peptide bonds (–CO–NH–) in close proximity. A positive test requires at least two consecutive peptide linkages. **Step 2: Analyze Glycine** Glycine is a single amino acid with no peptide bonds. - Result: **Negative test** **Step 3: Analyze Glycylalanine** Glycylalanine is a dipeptide (two amino acids linked by one peptide bond). - Only 1 peptide bond present - Result: **Negative test** **Step 4: Analyze Tripeptide** A tripeptide contains three amino acids linked by two consecutive peptide bonds. - Contains 2 or more peptide bonds ✓ - Result: **Positive test** **Step 5: Analyze Biuret** Biuret is a compound with the structure: H₂N–CO–NH–CO–NH₂ - Contains two consecutive peptide-like bonds (–CO–NH– groups) - Specifically designed to give a positive Biuret test - Result: **Positive test** **Step 6: Count positive results** Compounds giving positive Biuret test: Tripeptide and Biuret = 2 compounds Therefore, the answer is **2**.