Deisenhofer, Johann (1943-) is a German biophysicist who shared the 1988 Nobel Prize in chemistry with colleagues Robert Huber and Hartmut Michel, for their work in mapping the chemical reaction at the center of photosynthesis.

Deisenhofer was born on Sept. 30, 1943, in Zusamaltheim, Bavaria. He went away to school in 1956. He graduated from the Holbein Gymnasium in 1963. He then took the “Abitur,” an examination that German students must take in order to go to a university. He passed and was awarded a scholarship.

After a year and a half in military service, Deisenhofer began his study of physics at the Munich Technical University. His interest changed to solid-state physics and then to biophysics. In 1971, he went to the Max Planck Institute under the direction of Huber. Three years later, he received his Ph.D. degree in biophysics. He stayed on at Huber's lab conducting research in X-ray crystallography. He also helped develop computer software to assist in the mapping of crystals.

In 1979, Michel joined Huber's laboratory. He had been studying photosynthesis and was trying to develop a method for analyzing the molecules essential to the reaction. Focusing on a particular molecule called photosynthetic reaction center, Michel discovered a way to crystallize it. Once crystallized, the molecule took on the form of a crystal lattice that could be analyzed atom by atom through X-ray crystallography. Michel had developed the crystallizing technique but asked Huber to help him find a collaborator to analyze the crystals he produced. Huber referred Michel to Deisenhofer, and a four-year collaboration began. Deisenhofer used his X-ray crystallography techniques to determine the position of more than 10,000 atoms in the molecule. He also produced the first three-dimensional analysis of a membrane protein (membrane proteins make up the photosynthetic reaction center).

In March 1988, he became professor of biochemistry and investigator at the Howard Hughes Medical Institute at the University of Texas Southwestern Medical Center at Dallas.