CHAPTER 1
Expressions of the Pentose Phosphate Cycle*
N. G. PON
Department of Biochemistry, University of California, Riverside, California
I. General Considerations
2
II. Description of the Pentose Phosphate Cycle
2
III. Role of the Pentose Phosphate Cycle
5
IV. Brief History
5
A. The Oxidative Pentose Phosphate Cycle
5
B. The Reductive Pentose Phosphate Cycle
7
V. Criteria for the Presence of the Pentose Phosphate Cycle ....
9
A. Inhibitors as Indicators of Alternate Pathways of Metabolism .
.
10
B. Presence of Pentose Phosphate Cycle Intermediates in Tissues .
.
10
C. Pentose Phosphate Pathway Intermediates as Substrates for
Respiration
11
D. Transformation of Pentose Phosphate Cycle Intermediates
.
.
12
E. Presence of Enzymes of the Pentose Phosphate Pathway ...
13
F. Metabolism of C
14
-Labeled Substrates
15
VI. Chordates
17
A. Mammals
17
B. Birds
57
C. Reptiles, Amphibians, and Fish .
59
VII. Arthropods
60
VIII. Segmented Worms
62
IX. Mollusks
62
X. Echinoderms
62
XI. Roundworms
63
XII. Flatworms
63
XIII. Protozoa
64
XIV. Bacteria and Fungi
65
XV. Algae
68
XVI. Higher Plants
71
A. The Oxidative Pentose Phosphate Cycle
71
B. The Reductive Pentose Phosphate Cycle
75
XVII. Closing Remarks
78
References
79
* The work described in this paper was supported, in part, by the United States
Atomic Energy Commission, Lawrence Radiation Laboratory, Berkeley, California.
1