(nitric acid), HClO 3 (chloric acid), and HC 2 H 3 O 2
(acetic acid). Acetic is a ternary acid by this defini-
tion, but in general organic acids are not included in
this class.
Also called oxyacids (or oxoacids).
terpenes Hydrocarbon solvents, compounds com-
posed of molecules of hydrogen and carbon. They form
the primary constituents in the aromatic fractions of
scented plants, e.g., pine oil. Others include turpentine
and camphor oil.
tertiary structure The overall three-dimensional
structure of a BIOPOLYMER. For proteins, this involves
the side-chain interactions and packing of SECONDARY
STRUCTUREmotifs. For NUCLEIC ACIDs this may be the
packing of stem loops or supercoiling of DOUBLE
HELICES.
tetrahedral Refers to a solid with four plane faces.
Describes a configuration with one atom in the center
and four atoms at the corners of a tetrahedron.
tetrahedral hole A hole or space in a crystal sur-
rounded by four atoms or ions arranged toward the
corners of a tetrahedron.
tetrahedral intermediate A reaction INTERMEDIATE
in which the bond arrangement around an initially
double-bonded carbon atom (typically a carbonyl car-
bon atom) has been transformed from trigonal to tetra-
hedral. For example, aldol in the CONDENSATION
REACTIONof acetaldehyde (but most tetrahedral inter-
mediates have a more fleeting existence).
tetrahedron SeeCOORDINATION.
tetrahydrofolate A reduced FOLATEderivative that
contains additional hydrogen atoms in positions 5, 6,
7, and 8. Tetrahydrofolates are the carriers of acti-
vated one-carbon units and are important in the
biosynthesis of amino acids and precursors needed for
DNA synthesis.
See alsoFOLATE COENZYME.thalassemia A chronic inherited disease character-
ized by defective synthesis of HEMOGLOBIN. Defective
synthesis of the αchain of hemoglobin is called α-tha-
lassemia, and defective synthesis of the β-chain of
hemoglobin is called β-thalassemia. Thalassemias result
in anemia that can be severe and are found more fre-
quently in areas where malaria is endemic.Theorell, Axel Hugo Theodor(1903–1982) Swed-
ish Biochemist Axel Hugo Theodor Theorell was
born at Linköping, Sweden, on July 6, 1903, to Thure
Theorell, surgeon major to the First Life Grenadiers
practicing medicine in Linköping, and his wife, Ar-
mida Bill.
Theorell was educated at a state secondary school
in Linköping and started studying medicine in 1921 at
the Karolinska Institute. In 1924 he graduated with a
Bachelor of Medicine and spent three months studying
bacteriology at the Pasteur Institute in Paris. He
received an M.D. in 1930 and became lecturer in physi-
ological chemistry at the Karolinska Institute.
In 1924 he became part of the staff of the Medico-
Chemical Institution as an associate assistant and tem-
porary associate professor working on the influence of
the lipids on the sedimentation of the blood corpuscles.
In 1931 at Uppsala University, he studied the molecular
weight of myoglobin. The following year he was
appointed associate professor in medical and physio-
logical chemistry at Uppsala University and continued
and extended his work on myoglobin.
From 1933 until 1935 he held a Rockefeller fellow-
ship and became interested in oxidation enzymes. He
produced, for the first time, the oxidation enzyme
called “the yellow ferment” and he succeeded in split-
ting it reversibly into a coenzyme part, which was
found to be flavinmononucleotide, and a colorless pro-
tein part.
Returning to Sweden in 1935, he worked at the
Karolinska Institute, and in 1936 he was appointed
head of the newly established biochemical department
of the Nobel Medical Institute, opened in 1937.
He carried out research on various oxidation
enzymes, contributing to the knowledge of cytochromeTheorell, Axel Hugo Theodor 265