\documentclass[12pt]{article}
\usepackage{amsmath,amssymb,amsfonts}
\begin{document}
Geometrical properties of protein ground states are studied using an algebraic
approach. It is shown that independent from intermonomer interactions, the
collection of ground state candidates for any folded protein is
unexpectedly small: For the case of a two-parameter hydrophobic-polar
lattice model for $L$-mers, the number of these candidates grows only as
$L^2$. Moreover, by exact enumeration, we show there are some
sequences which have one absolute unique native state. These absolute
ground states have perfect stability against any change of intermonomer
interaction potential.
\end{document}