Crystal Growth of a Heme Protein, Cytochrome c′ from Alcaligenes xylosoxidans NCIMB 11015

Abstract

The three dimensional structure of protein molecule is essential for understanding numerous cell functions and the industrial utilization of biological systems. It is important to determine the three dimensional structure of biological macromolecule components by certain techniques. Both X-ray and neutron crystallographic techniques require high-quality crystals to obtain precise structural information. Microgravity has so far been expected to give a better condition for protein crystal growth than on the earth. Although physical and chemical approach for the protein crystal growth under the microgravity is strongly believed to be important for the systematic protein crystal design, there are few investigations for the protein crystal growth from the mechanisctic approach of molecular assembly. Cytochromes c' are a class of c-type cytochrome, which have been found in several photosynthetic bacteria and denitrifying bacteria. Cytochrome c' from denytrifying bacteria is a positively charged protein containing a heme prothetic group covalently bound to the protein backborn through two thioether linkages as well as cytochrome c. In the space experiment STS-107, cytochrome c' from Achromobacter xylosoxifdans NCIMB 11015 was used for the crystal growth experiments based on the crystal growth mechanisms. In this paper, a preliminary X-ray topograph analyses of the crystal of cytochrome c' are also provided.