Alexander Dounce

Alexander L. Dounce
Alexander Dounce, ca. 1947–1950
Born	(1909-12-07)December 7, 1909 New York, United States
Died	April 24, 1997(1997-04-24) (aged 87) Rochester, New York, United States
Nationality	United States
Alma mater	Hamilton College, Cornell University
Known for	Dounce homogenizer; co-discovery of catalase crystallization
Spouse(s)	Anna Elizabeth Dounce
Scientific career
Fields	Organic chemistry, biochemistry
Institutions	Cornell University (1936–1941), University of Rochester (1941–retirement),
Thesis	Study of dihydrofurans and the dehydration rearrangement of 2,3-ethylenic 1,4-diols. (1935)
Doctoral advisor	James B. Sumner
Signature

Alexander Latham Dounce (December 7, 1909 – April 24, 1997) was an American professor of biochemistry. Among his fields of study were the isolation and purification of cellular organelles, protein crystallization, enzymes (specifically catalase), DNA binding proteins, and the chemical basis of protein synthesis. He also invented the Dounce homogenizer, which was named after him.

Alexander Dounce was born on December 7, 1909, in New York. He began his undergraduate studies at Hamilton College but later moved to Cornell University, where he also did his doctoral studies in the lab of James B. Sumner, a pioneer in protein crystallization. Dounce received his PhD in organic chemistry in 1935, the title of his thesis being "Study of dihydrofurans and the dehydration rearrangement of 2,3-ethylenic 1,4-diols". According to Marshall W. Nirenberg, another biochemist who knew Dounce personally, "during his [Dounce's] final doctoral exam when his doctoral committee got together to ask him questions after he had finished his thesis research, his mentor, Sumner, asked him the question, 'How do proteins synthesize other proteins?' He [Dounce] said that question remained in his mind ever since then."

After his graduation, Dounce stayed in Sumners lab and did work on enzymes, particularly on enzyme isolation and purification. Together with Sumner, he achieved the first crystallization of the enzyme catalase in 1937. In 1941, Dounce moved to the Department of Biochemistry at University of Rochester Medical School, where he worked on the mechanism of uranium poisoning for the Manhattan Project. After the end of World War II, he focussed on studying cell nuclei and particularly the isolation of intact nuclei from tissue, which was a new field of research at the time. In 1952, Alexander Dounce and Ernest Kay, who was Dounce's first PhD student, published a new method for DNA isolation and purification from nuclei employing sodium dodecyl sulfate that became widely used.