The New Era of Microcrystallography

Abstract

The function of a protein dictates its physical state in a cell.
Evolution has imparted selection pressure on proteins to maximize their
function and minimize cell death. Most of the proteins exist in their soluble
form inside or outside the cells. However, a small fraction of proteins
in the total protein pool crystallizes with functional consequence. These
in vivo-grown protein crystals perform a diversity of functions, ranging
from food storage to defense. Sometimes limited by the volume of the
cells and the cellular concentration of proteins, these crystals are very
small in size. Hence, it has been difficult to carry out conventional X-ray
crystallography on these crystals. With the advent of microcrystallography,
it is now possible to study the structures of these tiny crystals. In
this review, some of the diverse examples of in vivo crystals and the new
approaches towards microcrystallography are summarized.