The biggest known molecule is titin, also called connectin. It’s a giant protein found in human muscle.
🔬 1. Name: Titin (scientific name: connectin)
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Also known for having the longest chemical name (over 189,000 letters!).
🧪 2. Size and Atoms:
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Molecular formula (simplified): ~C₁₆₹₈₁₈₆H₂₇₀₄₁₃N₄₅₆₁₇O₈₀₈₀₈S₉₁₃
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Number of atoms: Over 244,000 atoms in a single molecule
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Molecular weight: ~3,000,000 daltons (3 megadaltons)
🧬 3. Structure:
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Titin is composed of ~34,000 amino acids.
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Its structure has repeating modules (like Lego blocks), mainly:
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Immunoglobulin-like domains (Ig)
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Fibronectin type III domains (Fn3)
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It is highly folded, allowing it to be spring-like in muscles.
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Looks like a long, coiled rope with sections that fold and unfold.
(Schematic of domain arrangement; not atom-level resolution)
💪 4. Function in the Body:
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Location: Inside sarcomeres (basic muscle units).
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Function:
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Acts like a molecular spring in muscles.
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Maintains muscle elasticity and helps return stretched muscles to their resting length.
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Helps stabilize sarcomere structure and prevent overstretching.
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Involved in muscle signaling and gene regulation under stress.
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🔍 Fun Fact:
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If unfolded, one titin molecule can be over 1 micron long—that’s about 1,000 times longer than typical proteins.
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Some call titin the "king of proteins" due to its size.