Thomas Arthur Steitz (born August 23, 1940) is a Sterling Professor of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University, New Haven, Connecticut, USA. Steitz was awarded the 2009 Nobel Prize in Chemistry along with Venkatraman Ramakrishnan and Ada Yonath "for studies of the structure and function of the ribosome". Steitz also won the Gairdner International Award in 2007 "for his studies on the structure and function of the ribosome which showed that the peptidyl transferase was an RNA catalyzed reaction, and for revealing the mechanism of inhibition of this function by antibiotics".

Born in Milwaukee, Wisconsin, Steitz studied chemistry as an undergraduate at Lawrence University. While there he was a member of the fraternity, Delta Tau Delta,the Delta Nu chapter.

He received a Ph.D. in biochemistry and molecular biology from Harvard University in 1966 where he worked under direction of subsequent 1976 chemistry Nobel Prize winner William N. Lipscomb, Jr. While at Harvard after the training task of determining the structure of the small molecule methyl ethylene phosphate, Steitz made these contributions to determining the atomic structures of carboxypeptidase A and aspartate carbamoyltransferase, each the largest atomic structure determined in its time. The structure of the large 50S ribosomal subunit, which Steitz later determined in his own lab at Yale University, and for which Steitz was awarded the Nobel Prize is even larger.

He did his postdoctoral research as a Jane Coffin Childs Postdoctoral Fellow at the MRC Laboratory of Molecular Biology at Cambridge University during 1967-1970. He was also a Macy Fellow doing research at the University of Göttingen during 1976-1977 and a Fairchild Scholar at the California Institute of Technology during 1984-1985.

He is married to Joan A. Steitz, also a Sterling Professor of Molecular Biophysics and Biochemistry at Yale. In 2010, he lives in Branford, Connecticut.

See also:

• "Thomas A. Steitz - Biographical". Nobelprize.org.
• "Thomas A. Steitz - Photo Gallery". Nobelprize.org.