Biology Forums - Study Force

The oxygen-carrying protein myoglobin is composed of 153 amino acids, linked by covalent bonds into an unbranched polymeric chain. If all amino acids in the chain assume a regular and periodic conformation in which each residue is separated from the next by a distance of 1.5 Å, then the molecule could be as long as 230 Å (153 residues × 1.5 Å per residue). Analysis of the myoglobin molecule in solution reveals that it is no more than 45 Å in length. What does this observation tell you about how a linear polymer of amino acids might behave in solution?

Because the length of the myoglobin molecule in solution is much less than its extended length, it is likely that the polymeric chain is folded into a compact structure. This conclusion was first reached in the 1930s when studies on the radius of gyration of certain proteins showed that they are shorter than their predicted length. The
globular structure of a soluble protein was visualized in detail by John Kendrew in 1957 when he used x-ray analysis to show that myoglobin is an assembly of rodlike chains with overall dimensions of 45 × 35 × 25 Å. It is now well established that most soluble proteins fold into globular, compact structures in solution. Discussion of those folded structures as well as how they undergo folding will be discussed at length in
the text.

Thank you.