Field of Science

Water wires and hydrophobics

Quick survey of two interesting articles

P. Balaram's group at the Indian Institute of Science in Bangalore has turned a serendipitous observation into a nice study of a single file water wire inside a hydrophobic peptide nanotube. Based on the crystallographic data two models have been proposed for this wire. Such a structure can be the starting point for interesting MD simulations.
DOI: 10.1021/ja9038906

A group at Boston University and SLAC has found an explanation for the catalytic action of acetoacetate decarboxylase that refutes an elegant explanation provided by the famous late bioorganic chemist Frank Westheimer. Westheimer had proposed that a key lysine involved in nucleophilic attack was neutral because of proximity to another lysine; the electrostatic repulsion between two charged lysines would not favor the ionized state for both of them. The present group has obtained the crystal structure for the enzyme and finds that the two lysines are in fact far apart. Thus, electrostatic repulsion could not be responsible for the neutral nature of the lysine. Instead, using an elegant set of experiments, they find that it's being in a hydrophobic cavity that favors the lack of ionization.

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