if anyone can show me the equation and how to solve this. I\'ll appreciate it Fr

Question

if anyone can show me the equation and how to solve this. I'll appreciate it

From chemistry, we know that each methylene (-CH2-) group in a straight-chain hydrocarbon advances the chain length by about 0.13 nm. And from studies of protein structure, we know that one turn of an helix includes 3.6 amino acid residues and extends the long axis of the helix by about 0.56 nm. Use this information to answer the following: Approximately how many amino acids must a helical transmembrane segment of an integral membrane protein have if the segment is to span the lipid bilayer defined by two palmitate molecules laid end to end?

Explanation / Answer

Given that each methylene(-Ch2-) group in a straight chain hydrocarbon advances the chain length by 0.13 nm and bond angle of carbon is 109, so the distance between the first and third carbons in acyl chain (calculated by trignometry) is 0.20nm. For palmitate (16:0),the lenghth of the extended chain is about 8 x 0.20nm, that is 1.6nm. Two palmitate chains end to end (as in bilayer) would extend 3.2 nm.

As given, each turn of helix extends the long axis of the helix by 0.56nm. So total number of turns in helix will be

3.2nm/0.56nm = 5.7 turns approx

And each turns contains 3.6 amino acids

So total number of amino acids in helix will be

5.7 × 3.6 = 20 amino acids (approx)

so the answer will be amino acids

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