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F. M. HUENNEKENS AND H. R. WHITELEY
phate compound present in a given phylum does not appear to constitute a valid criterion of phyletic relationship.
It has been suggested that the distribution of N-phosphate compounds could be the result of convergent evolution, with the various
amidine phosphates arising independently at different times in different
animals. The distribution of these compounds could also be accounted
for by postulating the evolution of a common synthetic pathway yielding the guanido group with subsequent mutations leading to the formation of two main compounds (phosphocreatine and phosphoarginine);
the presence of both compounds in some invertebrates could be attributed to still later mutations (435). Wald (436) has suggested that
if possession of either phosphocreatine or phosphoarginine were important for survival, selection would have eliminated the other. Thus,
the wide distribution of phosphocreatine and phosphoarginine in the
animal kingdom may indicate that they are nearly equivalent in function. The restricted distribution of phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate, on the other
hand, may result from selection or rare mutations.
The above discussion has focused attention upon two of the current
problems in this particular area of comparative biochemistry: namely,
that (a) inadequate data on the distribution of certain classes of "energy-rich" compounds, notably inorganic polyphosphates and carboxyl
phosphates, precludes any detailed phyletic correlation, while (b) the
accumulation of more complete data on the amidine phosphates has
illustrated the complexity of such relationships. Differences in the distribution of certain key biochemical compounds must obviously underlie morphological differences, and conversely, the morphological and
embryological similarities of related organisms must result from the
expression of common biochemical attributes. The identification of
these key compounds, elucidation of their role in metabolism, and the
analysis of their distribution in the plant and animal kingdoms will undoubtedly remain a major goal in the field of comparative biochemistry.
ACKNOWLEDGMENTS
We would like to thank Drs. M. J. Osborn and A. H. Whiteley for many helpful
discussions and for reading the manuscript.
References
1. N. W. Pirie, in "Perspectives in Biochemistry" (J. Needham and D. E. Green,
eds.), p. 11. Cambridge University Press, London and New York, 1937.
2. H. J. Müller, Science 121, 1 (1955).
3. A. Szent-Györgyi, Science 124, 873 (1956).
4. B. W. Gabrio, C. A. Finch, and F. M. Huennekens, Blood 11, 103 (1956).
F. M. HUENNEKENS AND H. R. WHITELEY
phate compound present in a given phylum does not appear to constitute a valid criterion of phyletic relationship.
It has been suggested that the distribution of N-phosphate compounds could be the result of convergent evolution, with the various
amidine phosphates arising independently at different times in different
animals. The distribution of these compounds could also be accounted
for by postulating the evolution of a common synthetic pathway yielding the guanido group with subsequent mutations leading to the formation of two main compounds (phosphocreatine and phosphoarginine);
the presence of both compounds in some invertebrates could be attributed to still later mutations (435). Wald (436) has suggested that
if possession of either phosphocreatine or phosphoarginine were important for survival, selection would have eliminated the other. Thus,
the wide distribution of phosphocreatine and phosphoarginine in the
animal kingdom may indicate that they are nearly equivalent in function. The restricted distribution of phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate, on the other
hand, may result from selection or rare mutations.
The above discussion has focused attention upon two of the current
problems in this particular area of comparative biochemistry: namely,
that (a) inadequate data on the distribution of certain classes of "energy-rich" compounds, notably inorganic polyphosphates and carboxyl
phosphates, precludes any detailed phyletic correlation, while (b) the
accumulation of more complete data on the amidine phosphates has
illustrated the complexity of such relationships. Differences in the distribution of certain key biochemical compounds must obviously underlie morphological differences, and conversely, the morphological and
embryological similarities of related organisms must result from the
expression of common biochemical attributes. The identification of
these key compounds, elucidation of their role in metabolism, and the
analysis of their distribution in the plant and animal kingdoms will undoubtedly remain a major goal in the field of comparative biochemistry.
ACKNOWLEDGMENTS
We would like to thank Drs. M. J. Osborn and A. H. Whiteley for many helpful
discussions and for reading the manuscript.
References
1. N. W. Pirie, in "Perspectives in Biochemistry" (J. Needham and D. E. Green,
eds.), p. 11. Cambridge University Press, London and New York, 1937.
2. H. J. Müller, Science 121, 1 (1955).
3. A. Szent-Györgyi, Science 124, 873 (1956).
4. B. W. Gabrio, C. A. Finch, and F. M. Huennekens, Blood 11, 103 (1956).