In 1926 he was appointed the Royal Society’s
Foulerton Research Professor and was in charge of the
Biophysics Laboratory at University College until
1952.
His work on muscle function, especially the obser-
vation and measurement of thermal changes associated
with muscle function, was later extended to similar
studies on the mechanism of the passage of nerve
impulses. He coined the term oxygen debt after his
own interests in recovery after exercise.
He discovered and measured heat production asso-
ciated with nerve impulses and analyzed physical and
chemical changes associated with nerve excitation,
among other studies. In 1922 he won the Nobel Prize
in physiology or medicine (with OTTO MEYERHOF) for
work on chemical and mechanical events in muscle
contraction, such as the production of heat in muscles.
This research helped establish the origin of muscular
force in the breakdown of carbohydrates while forming
lactic acid in the muscle.
His important works include Muscular Activity
(1926) and Muscular Movement in Man (1927), as
well as Living Machinery(1927), The Ethical Dilemma
of Science and Other Writings(1960), and Traits and
Trials in Physiology(1965).
He was a member of several scientific societies and
was elected a fellow of the Royal Society in 1918, serv-
ing as secretary for the period 1935–45 and as foreign
secretary in 1946. Hill died on June 3, 1977.
HiPIP Formerly used abbreviation for high-potential
IRON-SULFUR PROTEIN, now classed as a FERREDOXIN.
An ELECTRON-TRANSFER PROTEINfrom photosynthetic
and other bacteria, containing a [4FE-4S] CLUSTER
which undergoes oxidation-reduction between the
[4Fe-4S]2+and [4Fe-4S]3+states.
See alsoPHOTOSYNTHESIS.
hirudin A nonenzymatic chemical secreted from the
leech that prevents blood clotting. Now genetically
engineered as lepirudin, desirudin, and a synthetic
bivalirudin and used as anticoagulants.
histamine A hormone and chemical transmitter
found in plant and animal tissues. In humans it is
involved in local immune response that causes blood
vessels to dilate during an inflammatory response; also
regulates stomach acid production, dilates capillaries,
and decreases blood pressure. It increases permeability
of the walls of blood vessels by vasodilation when
released from mast cells and causes the common symp-
toms of allergies such as running nose and watering
eyes. It will also shut the airways in order to prevent
allergens from entering, making it difficult to breathe.
Antihistamines are used to counteract this reaction.histone A basic unit of CHROMATINstructure. Several
types of protein are characteristically associated with
the DNA in chromosomes in the cell nucleus of
EUKARYOTEs. They function to coil DNAinto nucleo-
somes that are a combination of eight histones (a pair
each of H2A, H2B, H3, and H4) wrapped by two turns
of a DNA molecule. A high number of positively
charged amino acids bind to the negatively charged
DNA.Hodgkin, Dorothy Crowfoot(1910–1994) British
Crystallographer Dorothy Crowfoot was born in Cairo
on May 12, 1910, the daughter of John Winter Crow-
foot from the Egyptian Education Service, and Grace
Mary Crowfoot (née Hood), an archaeologist and
botanist. Dorothy became interested in chemistry at age
10 but almost gave it up for a career in archaeology.
She attended Oxford and Somerville College from
1928 to 1932, combining archaeology and chemistry,
but after attending a special course in crystallography,
she turned her interests to X-ray crystallography.
In 1933 after a brief stint at Cambridge and
Oxford, she returned to Somerville and Oxford in
1934 and remained there for most of her life teaching
chemistry. In 1934 she crystallized and X-ray pho-
tographed insulin, only the second protein to be stud-
ied. She went on to map the molecular structure of
penicillin (1947) and vitamin B12 (1956). In the late
1960s, she created a three-dimensional map of insulin.
In 1937, the same year she received a doctorate
from Cambridge, she married Thomas Hodgkin, with
whom she had three children.
In 1964 she was awarded the Nobel Prize in chem-
istry “for her determinations by X-ray techniques of
the structures of important biochemical substances.”Hodgkin, Dorothy Crowfoot 129