Leonor Michaelis (16 January 1875 – 8 October 1949) was a German
biochemist,
physical chemist
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mech ...
, and
physician
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
, known for his work with
Maud Menten
Maud Leonora Menten (March 20, 1879 – July 17, 1960) was a Canadian physician and chemist. As a bio-medical and medical researcher, she made significant contributions to enzyme kinetics and histochemistry and invented a procedure that rema ...
on
enzyme kinetics
Enzyme kinetics is the study of the rates of enzyme-catalysed chemical reactions. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. Studying an enzyme's kinetics in thi ...
in 1913, as well as for work on
enzyme inhibition,
pH and
quinones.
Early life and education
Leonor Michaelis was born in Berlin, Germany, on 16 January 1875, and graduated from the humanistic Koellnisches Gymnasium in 1893 after passing the Abiturienten Examen. He was Jewish. It was here that Michaelis's interest in physics and chemistry was first sparked as he was encouraged by his teachers to utilize the relatively unused laboratories at his school.
With concerns about the financial stability of a pure scientist, he commenced his study of medicine at
Berlin University
Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...
in 1893. Among his instructors were
Emil du Bois-Reymond
Emil Heinrich du Bois-Reymond (7 November 181826 December 1896) was a German physician and physiologist, the co-discoverer of nerve action potential, and the developer of experimental electrophysiology.
Life
Du Bois-Reymond was born in Berlin a ...
for
physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
,
Emil Fischer
Hermann Emil Louis Fischer (; 9 October 1852 – 15 July 1919) was a German chemist and 1902 recipient of the Nobel Prize in Chemistry. He discovered the Fischer esterification. He also developed the Fischer projection, a symbolic way of draw ...
for
chemistry, and
Oscar Hertwig for
histology
Histology,
also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vi ...
and
embryology
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos ...
.
During his time at Berlin University, Michaelis worked in the lab of Oscar Hertwig, even receiving prize for a paper on the histology of milk secretion. Michaelis's doctoral thesis work on cleavage determination in frog eggs led him to write a textbook on embryology. Through his work at Hertwig's lab, Michaelis came to know
Paul Ehrlich
Paul Ehrlich (; 14 March 1854 – 20 August 1915) was a Nobel Prize-winning German physician and scientist who worked in the fields of hematology, immunology, and antimicrobial chemotherapy. Among his foremost achievements were finding a cure ...
and his work on blood
cytology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
; he worked as Ehrlich's private research assistant from 1898 to 1899.
He passed his physician's examination in 1896 in
Freiburg
Freiburg im Breisgau (; abbreviated as Freiburg i. Br. or Freiburg i. B.; Low Alemannic: ''Friburg im Brisgau''), commonly referred to as Freiburg, is an independent city in Baden-Württemberg, Germany. With a population of about 230,000 (as o ...
, and then moved to Berlin, where he received his doctorate in 1897. After receiving his medical degree, Michaelis worked as a private research assistant to
Moritz Litten (1899–1902) and for
Ernst Viktor von Leyden (1902–1906).
[Leonor Michaelis 1875–1949]
A Biographical Memoir by L. Michaelis, D. A. MacInnes and S. Granick J
Life and work
From 1900 to 1904, Michaelis continued his study of clinical medicine at a municipal hospital in Berlin, where he found time to establish a chemical laboratory.
He attained the position of Privatdocent at the University of Berlin in 1903. In 1905 he accepted a position as director of the bacteriology lab in the Klinikum Am Urban, becoming Professor extraordinary at
Berlin University
Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...
in 1908. In 1914 he published a paper suggesting that
Emil Abderhalden
Emil Abderhalden (9 March 1877 – 5 August 1950) was a Swiss biochemist and physiologist. His main findings, though disputed already in the 1910s, were not finally rejected until the late 1990s. Whether his misleading findings were based on f ...
's notorious pregnancy tests could not be reproduced, a paper which fatally compromised Michaelis's position as an academic in Germany. In 1922, Michaelis moved to the Medical School of the
University of Nagoya (Japan) as Professor of
biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
, becoming one of the first foreign professors at a Japanese university, bringing with him several documents, apparatuses and chemicals from Germany. His research in Japan focused on potentiometric measurements and the cellular membrane.
In 1926, he moved to
Johns Hopkins University
Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consi ...
in
Baltimore
Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
as resident lecturer in medical research and in 1929 to the
Rockefeller Institute of Medical Research
The Rockefeller University is a private biomedical research and graduate-only university in New York City, New York. It focuses primarily on the biological and medical sciences and provides doctoral and postdoctoral education. It is classified ...
in New York City, where he retired in 1941.
The Michaelis-Menten equation
Michaelis's work with Menten led to the
Michaelis–Menten equation. This is now available in English.
for a steady-state rate
in terms of the substrate concentration
and constants
and
(written with modern symbols).
Classification of Inhibition types
Michaelis was one of the first to study enzyme inhibition, and to classify inhibition types as ''competitive'' or ''non-competitive''. In competitive inhibition the apparent value of
is increased, and in non-competitive inhibition the apparent value of
is decreased. Nowadays we consider the apparent value of
to be decreased in competitive inhibition, with no effect on the apparent value of
: Michaelis's competitive inhibitors are still competitive inhibitors by this definition. However, non-competitive inhibition by his criterion is very rare, but ''mixed inhibition'', with effects on the apparent values of both
and
is important. Some authors call this non-competitive inhibition, but it is not non-competitive inhibition as understood by Michaelis. The remaining important kind of inhibition, ''uncompetitive inhibition'', in which the apparent value of
is decreased
with no effect on the apparent value of
, was not considered by Michaelis. Fuller discussion can be found elsewhere.
Hydrogen ion concentration
Michaelis built virtually immediately on
Sørensen's 1909 introduction of the pH scale with a study of the effect of hydrogen ion concentration on invertase, and he became the leading world expert on pH and buffers. His book was the major reference on the subject for decades.
Quinones
In his later career he worked extensively on quinones, and discovered
Janus green as a
supravital stain for
mitochondria and the
Michaelis–Gutmann body in
urinary tract infection
A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...
s (1902). He found that
thioglycolic acid could dissolve
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
, a discovery that would come to have several implications in the cosmetic industry, including the
permanent wave ("perm").
A full discussion of his life and contributions to biochemistry may be consulted for more information.
"Catalysing" the Suzuki method of music teaching
During his time in Japan Michaelis knew the young
Shinichi Suzuki, later famous for the
Suzuki method of teaching the violin and other instruments. Suzuki asked his advice about whether he should become a professional violinist. Perhaps more honest than tactful, Michaelis advised him to take up teaching, and thus catalysed the invention of the Suzuki method.
Personal life and death
Michaelis was married to Hedwig Philipsthal; they had two daughters, Ilse Wolman and Eva M. Jacoby. Leonor Michaelis died on 8 October
[ or 10 October,Whonamedit Biography]
/ref> 1949 in New York City.
Honors
Michaelis was a Harvey Lecturer in 1924 and a Sigma Xi
Sigma Xi, The Scientific Research Honor Society () is a highly prestigious, non-profit honor society for scientists and engineers. Sigma Xi was founded at Cornell University by a junior faculty member and a small group of graduate students in 1886 ...
Lecturer in 1946. He was elected to be a Fellow of the American Association for the Advancement of Science in 1929, a member of the National Academy of Sciences in 1943. In 1945, he received an honorary LL.D. from the University of California, Los Angeles
The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California S ...
.[
]
References
{{DEFAULTSORT:Michaelis, Leonor
German biochemists
German medical researchers
1875 births
1949 deaths
Rockefeller University people
German physical chemists
Jewish chemists
Nagoya University faculty
Johns Hopkins University faculty
Physicians of the Charité