A protein that delivers metal to enzymes that require metal to function. (Cf. chaperone)
Metallochaperones are essential for the proper functioning of cells. They deliver heavy metal ions, such as copper and iron, to enzymes that need them to catalyze vital biochemical reactions, such as cellular respiration, DNA synthesis and antioxidant defense.
--"Viewing the Molecular Structure of a Metallochaperone," UniSci, 29 August 2001, <http://unisci.com/stories/20013/0829016.htm> (9 October 2003)
These proteins are tiny: perhaps 100,000 times smaller than the cell. Structural details have discovered by researchers at Northwestern University (notably Amy Rosenzweig). After growing crystals of the structures in solution, with the help of the Advanced Photon Source (APS) synchrotron at Argonne National Laboratory in Illinois, researchers could determine the position of atoms within the molecule by X-ray diffraction.

Research into metallochaperones is critical to understanding diseases linked to attributed to copper and oxidative stress, such as forms of amyotrophic lateral sclerosis.

Other sources:
Fellman, Megan. "Researchers work on nervous system disorders," Northwestern Observer, Vol. 17 No 4., 11 October 2001, <http://www.northwestern.edu/univ-relations/observer/stories/10_11_01/als.html> (9 October 2003)