234
GEORGE G. LATIES
1956a; W. D. Bonner and Yocum, 1956). A number of plausible systems
have been constructed in vitro which link the reduced coenzymes
(DPNH, TPNH) with molecular oxygen through glutathione and ascorbate (Mapson and Moustafa, 1956), glycolate (Zelitch and Ochoa,
1953; Zelitch, 1953), quiñones (Wosilait et al. 1954), or ascorbate
(Beevers, 1954). Although the participation of these systems in respiration has not been established, it seems likely that one or more of these
noncytochrome pathways of oxidation may function in vivo (see James,
1953b).
Whether or not phosphorylation accompanies the functioning of any
of the above alternative systems has not been investigated. There is no
reason a priori why it should not be expected. Examples of phosphorylation in soluble systems exist (Mahler, 1953). Furthermore, the recently
clarified role of metallo-flavoproteins in systems in which phosphorylation is known to occur (Mahler and Green, 1954), points to the possibility that phosphorylation may ultimately be demonstrated in some of
the mentioned plant systems which include one or more flavoprotein
components. Until such investigations are carried out, a discussion of
rate regulation in noncytochrome systems and the coupling of such systems to useful work within the cell must be deferred.
3. The Relation of the Pasteur Effect to Rate-Re gufoting
Mechanisms
One of Pasteur's many profound observations was that carbohydrate
utilization is repressed in air relative to its utilization under anaerobic
conditions. This phenomenon has since been known as the Pasteur effect.
Of the numerous possibilities which have been offered to explain the
Pasteur effect the most satisfactory would appear to be that which
ascribes the diminution of glycolysis in air to a paucity of inorganic
phosphate and phosphate acceptors caused by active aerobic phosphorylation. Alternative interpretations have been discussed by Turner (1951),
Simon (1953c), and Terner (1954).
Johnson (1941) was first to enunciate the role of aerobic phosphorylation in the Pasteur effect. Within recent years, experiments involving the use of uncoupling agents have done much to establish the
validity of Johnson's early hypothesis. Both dinitrocresol (Simon, 1953c)
and p-nitrophenol (Terner, 1954) have been shown simultaneously to
preclude aerobic phosphorylation and to abolish the Pasteur effect in
dried yeast preparations, and in mammary gland homogenates, respectively. Simon (1953b, c) has demonstrated the abolition of the oxidative
anabolism of glucose in whole yeast by dinitrocresol, together with the
concomitant appearance of aerobic fermentation. The latter term, which
implies simply the formation of alcohol in air, becomes less of a paradox
GEORGE G. LATIES
1956a; W. D. Bonner and Yocum, 1956). A number of plausible systems
have been constructed in vitro which link the reduced coenzymes
(DPNH, TPNH) with molecular oxygen through glutathione and ascorbate (Mapson and Moustafa, 1956), glycolate (Zelitch and Ochoa,
1953; Zelitch, 1953), quiñones (Wosilait et al. 1954), or ascorbate
(Beevers, 1954). Although the participation of these systems in respiration has not been established, it seems likely that one or more of these
noncytochrome pathways of oxidation may function in vivo (see James,
1953b).
Whether or not phosphorylation accompanies the functioning of any
of the above alternative systems has not been investigated. There is no
reason a priori why it should not be expected. Examples of phosphorylation in soluble systems exist (Mahler, 1953). Furthermore, the recently
clarified role of metallo-flavoproteins in systems in which phosphorylation is known to occur (Mahler and Green, 1954), points to the possibility that phosphorylation may ultimately be demonstrated in some of
the mentioned plant systems which include one or more flavoprotein
components. Until such investigations are carried out, a discussion of
rate regulation in noncytochrome systems and the coupling of such systems to useful work within the cell must be deferred.
3. The Relation of the Pasteur Effect to Rate-Re gufoting
Mechanisms
One of Pasteur's many profound observations was that carbohydrate
utilization is repressed in air relative to its utilization under anaerobic
conditions. This phenomenon has since been known as the Pasteur effect.
Of the numerous possibilities which have been offered to explain the
Pasteur effect the most satisfactory would appear to be that which
ascribes the diminution of glycolysis in air to a paucity of inorganic
phosphate and phosphate acceptors caused by active aerobic phosphorylation. Alternative interpretations have been discussed by Turner (1951),
Simon (1953c), and Terner (1954).
Johnson (1941) was first to enunciate the role of aerobic phosphorylation in the Pasteur effect. Within recent years, experiments involving the use of uncoupling agents have done much to establish the
validity of Johnson's early hypothesis. Both dinitrocresol (Simon, 1953c)
and p-nitrophenol (Terner, 1954) have been shown simultaneously to
preclude aerobic phosphorylation and to abolish the Pasteur effect in
dried yeast preparations, and in mammary gland homogenates, respectively. Simon (1953b, c) has demonstrated the abolition of the oxidative
anabolism of glucose in whole yeast by dinitrocresol, together with the
concomitant appearance of aerobic fermentation. The latter term, which
implies simply the formation of alcohol in air, becomes less of a paradox