Esmond Emerson Snell (September 22, 1914 – December 9, 2003) was an American biochemist who spent his career researching vitamins and nutritional requirements of bacteria and yeast.

He is well known for his study of lactic acid-producing bacteria, developing microbiological assays for a number of key nutrients; the discovery of more than half of known vitamins has been attributed to the use of this work.

He then moved back to his alma mater in 1945, joining the biochemistry faculty of the University of Wisconsin and remaining there until 1951, when he returned to Austin to occupy newly constructed laboratory space.

[2][3][4][5] During his career Snell served on a number of scientific journal editorial boards, most notably as the editor of the Annual Review of Biochemistry from 1968 to 1983 and of Biochemical and Biophysical Research Communications from 1970 to 1985.

His early work developing microbiological assays for key nutrients has been credited with facilitating the discovery of at least half of known vitamins due to their ease of use compared to more traditional animal studies.

In a series of experiments beginning in the 1940s and later conducted with student David Metzler, a general mechanism for the catalytic cycle of pyridoxal-dependent enzymes was discovered.

[1][3] In recognition of his contributions to the study of vitamin B6 biochemistry, the 1999 meeting in a regular series of international symposia on pyridoxal catalysis was dedicated to Snell.