Ganesh Natrajan was born on the 14th of April, 1973 in Alleppey, Kerala, India. In 1988, he completed his secondary schooling at the St. Anthony’s High School in Hyderabad, India. Upon completing his Master’s degree in Physics in 1996 at the University of Hyderabad, India, he enrolled at the Indian Institute of Science in Bangalore as a Research Scholar. In 1999, he moved to The Netherlands to begin his PhD in the laboratory of Prof Titia K Sixma at the Netherlands Cancer Institute in Amsterdam. His research has been primarily concerned with the use of X ray crystallographic structure determination, coupled with other biochemical assays, to study the Escherichia coli DNA mismatch repair enzyme MutS. Following the submission of this thesis, he will be working as a Post Doctoral Fellow in the lab of Dr Laurent Terradot-Piot in the Macromolecular Crystallography Group, at the European Synchrotron Radiation Facility in Grenoble, France. The research presented in this thesis was carried out between December 1999 and December 2005.