Moses Kunitz (December 19, 1887 – April 20, 1978) was a Russian-American

biochemist Biochemists are scientists who are trained in biochemistry. They study chemical processes and chemical transformations in living organisms. Biochemists study DNA, proteins and Cell (biology), cell parts. The word "biochemist" is a portmanteau of ...

who spent most of his career at

Rockefeller University The Rockefeller University is a Private university, private Medical research, biomedical Research university, research and graduate-only university in New York City, New York. It focuses primarily on the biological and medical sciences and pro ...

. He is best known for a series of experiments in purification and

crystallization Crystallization is a process that leads to solids with highly organized Atom, atoms or Molecule, molecules, i.e. a crystal. The ordered nature of a crystalline solid can be contrasted with amorphous solids in which atoms or molecules lack regu ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s, contributing to the determination that

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s are proteins.

Early life and education

Kunitz was born in

Slonim Slonim is a town in Grodno Region, in western Belarus. It serves as the administrative center of Slonim District. It is located at the junction of the Shchara and Isa (river), Isa rivers, southeast of Grodno. As of 2025, it has a population of ...

(then part of Russia, now in Belarus) on December 19, 1887. He was raised and educated there until his move to the United States, where he settled in New York City in 1909 and became an American citizen in 1915. Kunitz graduated from

Cooper Union The Cooper Union for the Advancement of Science and Art, commonly known as Cooper Union, is a private college on Cooper Square in Lower Manhattan, New York City. Peter Cooper founded the institution in 1859 after learning about the government-s ...

with a degree in chemistry in 1916 and then enrolled there for graduate school in electrical engineering. After three years in the program, he moved to

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

, from which he received a Ph.D. in biological chemistry in 1924. Kunitz began work as a technical assistant in Jacques Loeb's laboratory at

in 1913 and continued there throughout his graduate years. Loeb arranged for Kunitz to receive a staff appointment at Rockefeller after graduation.

Academic career

Kunitz' position at Rockefeller was originally secured by Jacques Loeb. After Loeb died in 1924, John H. Northrop succeeded him and retained Kunitz' position; the two would collaborate extensively on experiments involving protein crystallization for much of their remaining careers. Both Northrop and Kunitz moved to Rockefeller's Princeton, New Jersey campus in 1926; Kunitz returned to New York City in 1952. He then assumed

professor emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retirement, retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". ...

status but continued to work regularly in the laboratory until eventually retiring in 1970. Kunitz was awarded the Carl Neuberg Medal in 1957 in recognition of his long research career and noted technical skill in the laboratory, which was critical to his long series of successes in protein crystallization. He was elected to the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

in 1967.

Research

Kunitz is best known for his efforts in

protein crystallization Protein crystallization is the process of formation of a regular array of individual protein molecules stabilized by crystal contacts. If the crystal is sufficiently ordered, it will diffract. Some proteins naturally form crystalline arrays, ...

, successfully crystallizing a number of

s and enzyme precursor proteins, particularly

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products ...

s. Kunitz worked with

trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...

and

chymotrypsin Chymotrypsin (, chymotrypsins A and B, alpha-chymar ophth, avazyme, chymar, chymotest, enzeon, quimar, quimotrase, alpha-chymar, alpha-chymotrypsin A, alpha-chymotrypsin) is a digestive enzyme component of pancreatic juice acting in the duodenu ...

and their precursors, as well as

pepsin Pepsin is an endopeptidase that breaks down proteins into smaller peptides and amino acids. It is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pe ...

. He also studied protease inhibitors and devoted particular effort to the

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

trypsin inhibitor; the

inhibitor protein The inhibitor protein (IP) is situated in the mitochondrial matrix and protects the cell against rapid ATP hydrolysis during momentary ischaemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or orga ...

, its domain family, and a soybean

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

lacking this protein are all named after him. For their role in isolating, purifying, and crystallizing enzymes - a subject underscored by Kunitz' work with Northrop - John H. Northrop, Wendell M. Stanley, and James B. Sumner were awarded the

Nobel Prize in Chemistry The Nobel Prize in Chemistry () is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outst ...

in 1946. Kunitz himself was nominated three times for a share of a Nobel for this work. In addition to his work on crystallization of proteases, Kunitz also performed careful work in

enzymology An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

, characterizing the kinetics and thermodynamics of protease reactions. He worked on other proteins as well, in particular

ribonuclease Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within th ...

s, which were popular model systems for their small size and ease of crystallization. During World War II he worked on government-assigned crystallization projects and was noted for the facility with which he crystallized

hexokinase A hexokinase is an enzyme that irreversibly phosphorylates hexoses (six-carbon sugars), forming hexose phosphate. In most organisms, glucose is the most important substrate for hexokinases, and glucose-6-phosphate is the most important p ...

. Kunitz was widely recognized specifically for his craftsmanship and technical skill in the laboratory.

References

External links

Kunitz' papers in the Rockefeller Archive
{{DEFAULTSORT:Kunitz, Moses 1887 births 1978 deaths 20th-century American biochemists Columbia Graduate School of Arts and Sciences alumni Cooper Union alumni Emigrants from the Russian Empire to the United States Members of the United States National Academy of Sciences Rockefeller University faculty