What is special about water as a matrix of life?

Lawrence Pratt, Department of Chemical & Biomolecular Engineering, Tulane University

A striking feature of known biomolecular structures is that competing hydrophilic and hydrophobic interactions are exploited to achieve spatial organization.  It is natural then to expect that an effective alternative matrix of life should support both solvophobic and solvophilic interactions.  In addition, the availability of solvophobic and solvophilic microphases expands the chemistry that may operate.  Recent progress in understanding hydrophobic effects clarifies how they extend the temperature range for stable function of nanoscopic structures in water, e.g. micelles, membranes, and globular proteins, to encompass the temperature range of observed life, roughly (-20°C,120°C).  We discuss that recent progress in understanding hydrophobic effects, then on that basis survey liquids and liquid mixtures that might provide alternative media for life.   Particularly identified are polyalcohols (glycerol is a common laboratory example), amino-alcohols such as 2-amino ethanol, and amides such as formamide. These are also solvents with substantial dielectric constants and known electrolyte solution chemistry. Formation of surfactant micelles has been observed in all these solvents, and conventional studies of membranes and globular proteins are clearly possible too.  These are liquids and liquid mixtures that crystallize only with difficulty;  this possibility for avoiding crystallization damage also would be an advantage for a non-terrestrial matrix of life.

Oral