My Favorite Enzyme: For love of lectins

I was a student of Fred Smith at the University of Minnesota during 1952–1959. Smith was an Englishman who came to the USA to work on the Manhattan Project to build the atomic bomb. He was an outstanding carbohydrate chemist who was mentored by Sir Norman Haworth, Nobel Laureate in Chemistry for the synthesis of vitamin C (ascorbic acid). Smith was at the University of Birmingham when he received the call to come to the United States to work on ‘‘the bomb’’ because of his expertise in fluorine chemistry, a necessary technique for the separation of the 238 isotope of uranium as the hexafluoride. My work in Smith’s Lab involved studies on periodate oxidation products of glycosides. On receiving my PhD I stayed on as a postdoctoral fellow and instructor for two additional years. Happily for me, I was awarded a Guuggenheim Fellowship which allowed me to spend 2 years in Europe, first with Bill Whelan at the Lister Institute of Preventive Medicine in London, then with Bengt Lindberg in Stockholm. My work in both places involved the isolation, characterization, and chemical and enzymatic synthesis of oligosaccharides from natural sources. These were two wonderful years to work in and experience the scientific and cultural milieu of two different European laboratories. Bill Whelan was an enthusiastic and a helpful mentor. We both smoked at that time, and each morning ‘‘after lighting up,’’ we discussed my research. He always provided insightful and valuable ideas and approaches to pursue. My habit of arising early and getting to the lab in the early morning persisted while in London. At first, this did not go over well with the janitorial staff at the Lister. But after some time we became good friends and they greeted me with much enthusiasm each morning. There was another advantage from arriving early: I had the first use of equipment which was, at times, in short supply. While at the Lister I also had the opportunity of meeting Walter Morgan and his colleague Winifred Watkins. They had been studying the chemistry of human blood group substances for many years and were in a fierce competition with Elvin Kabat, Prof. of Immunochemistry at Columbia University. They were always first to grab a copy of the latest journal to see if Kabat had scooped them. Little did I realize, at the time, that our paths would converge. They did indeed when my lab took up a study of the lima bean lectin which they had used to assay for human type A blood group substance. I had many interesting and fruitful discussions with these colleagues during the following years. My first independent position was at the University of New York at Buffalo. To assist a colleague in the characterization of glycogen from microorganism, I decided to prepare concanavalin A from jack beans (Canavalia ensiformis) which was shown to precipitate glycogen. I followed the procedure of James Sumner who first prepared the protein. I decided to pass the purified protein through Sephadex, crossed-linked dextran, to assess its homogeneity. It did not emerge from the column! In an attempt to displace it from the column I suggested to a graduate student to add glucose. Pure concanavalin A was eluted! Address correspondence to: Irwin J. Goldstein, Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 481095606, USA. E-mail: igoldste@umich.edu Received 12 September 2009; accepted 12 September 2009