Reinhart Heinrich

Reinhart Heinrich (24 April 1946 – 23 October 2006) was a German biophysicist.

He was professor at the Humboldt University of Berlin, and best known as a founder of metabolic control theory. Among his services to the scientific community, Reinhart was associate editor of PLoS Computational Biology. His far-reaching theoretical work on metabolism, signal transduction, and other cellular processes has made him one of the most influential forerunners of present-day systems biology. Reinhart's many talents made him appear as a modern Renaissance man. He played the violin, and published an autobiographic novel (Jenseits von Babel) and several works of lyric poetry for which he received the Brigitte Reimann Prize.

Reinhart Heinrich was born in Dresden and lived at first in the Soviet Union, growing up in Kuybyshev/Куйбышев (as Samara was then known) where his father Helmut Heinrich, - a German mathematician turned aircraft constructor - had been taken after the Second World War to work. Having been educated as a theoretical physicist at Dresden University of Technology in East Germany, Reinhart conducted his postdoctoral research in the early 1970s at the Charité's Institute of Biochemistry in East Berlin. He could not fail to notice the absence of mathematical theory from cell biology as compared with other natural sciences. Enzyme kinetics was a notable exception. However, how enzymes affect the flux through a metabolic pathway was still discussed using the rather vague term rate-limiting step. Working with Professor Rapoport on mathematical models of glycolysis in red blood cells, Reinhart discovered a precise and general definition of rate limitation in metabolic pathways, for which he received in 1974 the Humboldt Prize. He extended his knowledge in this area, working over one year in Pushchino near Moscow with Professor Evgenii Selkov, who also worked on mathematic modelling of metabolic processes.

The parallel development of metabolic control theory by Henrik Kacser and Jim Burns in Edinburgh shows that the time was ripe for a quantitative understanding of metabolic regulation. Instead of postulating a single rate-limiting step, Reinhart's and Henrik Kacser's theories evaluated the degree of flux control exerted by an individual enzyme in a linear pathway or in a more complex network. The corresponding measure - termed flux control coefficient - turned out to be a truly systemic quantity, depending not only on the kinetic parameters of the enzyme itself but also on those of other enzymes, as well as on the position of the reaction in the network. Several years after its original publication, metabolic control theory became widely absorbed by biochemists. Control coefficients have been measured for many pathways, confirming the theoretical prediction that flux control is frequently shared by several reactions. This finding has recently become of very practical importance for the genetic engineering of large metabolic networks in biotechnology.

The dual approach - modeling concrete cellular processes and, at the same time, searching for general laws - has been a characteristic of Reinhart's work. The areas he worked in were amazingly diverse, including metabolic control, osmoregulation, cell shapes, signal transduction, vesicular transport, protein translation and transport, as well as the population dynamics of malaria parasites.

Perhaps his most favored questions were those of evolution. To understand the kinetic design of enzymes and enzymatic reaction networks, Reinhart strove to rationalize, in mathematical terms, the selective pressures and physico–chemical constraints that these systems were subjected to. Reinhart's work on this topic is full of original insight and makes specific predictions, some of which have begun to be tested successfully in recent years.

Reinhart was author of more than 160 research articles and, together with Stefan Schuster, wrote the book The Regulation of Cellular Systems - already a classic of cell systems biology. In addition to this large body of original work, he was a gifted mentor of young scientists and for more than ten years ran the highly successful interdisciplinary graduate program Dynamics and Evolution of Cellular Processes at Humboldt University, Berlin. In 1996 he received a Honorary degree from the University of Bordeaux.