The literature suggested that sugars are important. In Chemistry I had learned that organisms are composed of some classes of compounds. Selleck Volasertib After reading I considered sugars and proteins worth some attention, more than the other constituents. I ground leaves in summer and winter and analyzed the resulting soup as good as I could. This I did diligently for 3 years. I got several publications out of this but not much insight. Still, there was one observation worth following: freezing the soups caused precipitation more in summer than in winter (Ullrich and Heber 1958). There were more sugars in the soup in winter than in summer. CBL-0137 Addition of a decent amount

of sucrose to the summer soup decreased the precipitation caused by freezing.

What sedimented was green. I had read that green chlorophyll is a membrane constituent. Were chloroplast membranes sensitive to freezing? Did sugars protect them? If so, chloroplasts should contain more sugars P5091 cost in winter than in summer. How to show that? Sugars were thought to be mainly localized in the large vacuoles of leaf cells. Known procedures for chloroplast isolation employ aqueous media. Sugars dissolve in them. Visiting libraries, I had come across a short publication describing the isolation of nuclei from freeze-dried liver in an apolar organic solvent. Such solvents do not dissolve sugars. Could I isolate chloroplasts from freeze-dried leaves non-aqueously? It worked. The chloroplasts contained sugars. I published this and the method (Heber 1957) before related Amino acid (and better) work was done by Ralph Stocking in Davis, California (Stocking 1959). We had been unaware of one another but became friends later editing jointly a volume ‘Intracellular Interactions and Transport’ in the series ‘Encyclopedia of Plant Physiology’. In 1958 I got the Doctor rerum naturalium (Ph.D.) under Professor Ullrich at the University of Bonn. Two years later I committed an act of brashness. I asked my professor who was a very kind man, to be permitted to submit a thesis

for my ‘Habilitation’, that is to be officially permitted to lecture. This was, of course, immodest, to put it mildly. How to correct this mistake which I came to regret deeply? I went on a tour of Germany to see whether I could find another position. I also wrote a letter to Professor Melvin Calvin, Berkeley, already famous for his photosynthesis work, whether he would accept me as a postdoc. My frost hardiness work had made me realize that I knew nothing about photosynthesis. I received an offer from Professor Dietrich von Denffer, University of Giessen, for a position that included the possibility of habilitation, but also a letter from Professor Calvin: I could come provided I brought support with me. Both improved my standing with Professor Ullrich. I was no longer the lost son.