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SURFACE HYDRATION OF POLYPEPTIDES AND PROTEINS

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Natural Molecules as Analogs of Covalent Elements of Hydration

First of all, it should be realized that liquid water, as the environment in which all natural molecules evolved, provided the patterning for their selection and interactions. Thus, it should not be surprising that dimensions of vital molecules correspond to quantized transient linear elements of hydration.


Since natural molecules evolved in water, components of proteins and regulator molecules mimic the dimensions of ordered units of water molecules.

Although the theoretical length of three peptides in a linear segment is 11.4 Angstroms, the actual mean dimenAlthough the theoretical length of three peptides in a linear segment is 11.4 Angstroms, the actual mean dimension in beta-sheets, because of a slight twist, is 9.0 Angstroms, the same length as two 4.5A trimers (4x2.25A).10 In coils, the mean linear distance between each peptide is 1.5A, half that of linear segments. However, in discussing surface water it should be remembered that ordered forms are generated kinetically: they are not in equilibrium with the environment – they are short linear elements which form repetitively to fill space and provide structural stability; usually they last no more than 10-11 seconds.  Hydrogen-bond distances between water molecules and polar oxygen and nitrogen atoms may vary as much as 10% but kinetically-generated covalent hydrogen bonds hold water molecules about 2.76A apart at an angle of 109.5o at 25oC.  By forming repetitively in particular orientations on hydrophobic surfaces and between ions, they fill space to increase spatial stability in intermediate states but, thermodynamically, they are unstable.


Thus, it should not be surprising that molecules, which span open spaces in proteins to regulate functions, mimic linearly-ordered forms of water.  Estradiol, cyclic AMP and most neurotransmitters mimic transient linear elements of water molecules. In fact, glucose, the fundament al energy-storage and transport molecule of life, mimics the dimension of the water trimer. It and numerous other dimensional analogies are presented in www.linearwater.com and www.molecularcreation.com.