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Beta-Sheet Formation Beta-Turn Formation Carboxypeptidase A Assembly References

SURFACE HYDRATION OF POLYPEPTIDES AND PROTEINS

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VII – Carboxypeptidase A Coil Formation

If  we view the terminal 25 peptides on the acid end of the carboxypeptidase enzyme, we can see the extreme condition of linear hydration order which must be imposed by covalently-bonding surface water by 18 peptides with alpha methylenes, 4 threonines with methyl groups on beta carbons, two prolines with hydrophobic rings and a glycine flanked by large hydrophobic peptides.  Although the chain is illustrated as surrounded by linear elements, as mentioned before, coil-formation may begin within the ribosomal tunnel to avoid structurally disruptive associations.25




































Most likely the polypeptide segment from proline 288 to glycine 295, which would be released from the ribosome before the final eleven peptides, might wrap into a coil before final release.  Hydrophobic surfaces have such a high probability of associating together to form dehydrated assemblies that cells produce a number of proteins, called chaperones, to permit surfaces to rehydrate and reassemble into lower energy confirmations.  Notice that proline 288, even though it produces a bend in the chain, continues the coil. Also note that, even though hydration entropy has been increased dramatically, there are still substantial regions on the coil which induce quantized transient linear element formation.

Download PDF of this page   Download PDF Book  Assembly Covalent linear hydration around the 25 peptides on the end of the carboxypeptidase enzyme drives it into a coil.