102
P. K. STUMPF AND G. A. BARBER
zymes is not available (52). The classic /^-oxidation sequence of fatty
acid oxidation has been shown to occur in peanut mitochondria (78).
In the presence of CoA, ATP, Mn, a Krebs cycle acid, DPN, TPN, and
GSH, a long series of fatty acids is readily attacked and broken down
by the classical sequence. In higher plants there are therefore several
sequences for handling fatty acids; information on the orderly control
of these sequences is therefore of considerable importance. Fig. 6 summarizes this picture.
In animal tissues the dominating pathway is of course the ß-oxidative
sequence. This unusual mechanism readily explains the properties of
long-chain fatty acids as unique sources of energy for the requirements
of the cell. Recent reviews have summarized the many papers on this
subject (79).
VI. Conclusion
The development of the field of lipid oxidation closely paralleled
the growth of modern biochemistry. The early works of Knoop outlined
the concept of /?-oxidation by feeding appropriate derivatives of fatty
acid to whole animals. With the advent of radioisotopes a new period
of investigation was initiated by Schoenheimer in the late thirties. Leloir
was the first investigator in 1940 to prepare a homogenate which was
capable of limited oxidation of butyrate. The important discovery that
fatty acid oxidation in animal tissue was chiefly localized in the mitochondrial particle gave needed support of the value of cytological
localization of enzymes and their systems. Soon Green and Lynen and
their collaborators tackled the problem of ß-oxidation with modern
enzyme technology and completely elucidated the problem. At present
considerable interest is centered on the mechanism of action of the
ß-oxidation enzymes. The surprising discoveries of Wakil that fat synthesis involves a different and unique system quite apart from ^-oxidation implies that synthesis and degradation are not in many cases interrelated by a mere reversibility of an enzyme reaction but are indeed
complete and separate systems.
The cycle of events has made a complete turn for now the realm
of research in this area is not that of new enzyme systems but of the
clarification of problems more closely related to physiology: control of
rate of synthesis and rate of breakdown; what makes a tissue choose
between one or another system for its degradation sequence; what in a
tissue's genetic and somatic heritage contributes to the factors that results in a seed tissue such as the pea with 1-2$ of total fat whereas the
peanut can contain as much as 60% of its dry weight as neutral lipid;
what factors influence the ratio ot unsaturated to saturated fatty acids;
P. K. STUMPF AND G. A. BARBER
zymes is not available (52). The classic /^-oxidation sequence of fatty
acid oxidation has been shown to occur in peanut mitochondria (78).
In the presence of CoA, ATP, Mn, a Krebs cycle acid, DPN, TPN, and
GSH, a long series of fatty acids is readily attacked and broken down
by the classical sequence. In higher plants there are therefore several
sequences for handling fatty acids; information on the orderly control
of these sequences is therefore of considerable importance. Fig. 6 summarizes this picture.
In animal tissues the dominating pathway is of course the ß-oxidative
sequence. This unusual mechanism readily explains the properties of
long-chain fatty acids as unique sources of energy for the requirements
of the cell. Recent reviews have summarized the many papers on this
subject (79).
VI. Conclusion
The development of the field of lipid oxidation closely paralleled
the growth of modern biochemistry. The early works of Knoop outlined
the concept of /?-oxidation by feeding appropriate derivatives of fatty
acid to whole animals. With the advent of radioisotopes a new period
of investigation was initiated by Schoenheimer in the late thirties. Leloir
was the first investigator in 1940 to prepare a homogenate which was
capable of limited oxidation of butyrate. The important discovery that
fatty acid oxidation in animal tissue was chiefly localized in the mitochondrial particle gave needed support of the value of cytological
localization of enzymes and their systems. Soon Green and Lynen and
their collaborators tackled the problem of ß-oxidation with modern
enzyme technology and completely elucidated the problem. At present
considerable interest is centered on the mechanism of action of the
ß-oxidation enzymes. The surprising discoveries of Wakil that fat synthesis involves a different and unique system quite apart from ^-oxidation implies that synthesis and degradation are not in many cases interrelated by a mere reversibility of an enzyme reaction but are indeed
complete and separate systems.
The cycle of events has made a complete turn for now the realm
of research in this area is not that of new enzyme systems but of the
clarification of problems more closely related to physiology: control of
rate of synthesis and rate of breakdown; what makes a tissue choose
between one or another system for its degradation sequence; what in a
tissue's genetic and somatic heritage contributes to the factors that results in a seed tissue such as the pea with 1-2$ of total fat whereas the
peanut can contain as much as 60% of its dry weight as neutral lipid;
what factors influence the ratio ot unsaturated to saturated fatty acids;