CHAPTER 5
Onium Compounds and Their Biological Significance
G. L. CANTONI
Laboratory of Cellular Pharmacology, National Institute of Mental Health,
U. S. Public Health Service, Bethesda, Maryland
I. General Introduction, Natural Distribution, and Chemical Properties of
Onium Compounds
181
A. Natural Distribution of Onium Compounds
184
B. Considerations on the Chemistry of Onium Compounds
.
.
.
184
II. Aliphatic Quaternary Ammonium Compounds
189
A. Biochemistry of Aliphatic Quaternary Ammonium Compounds .
.
194
III. Heterocyclic Onium Compounds
202
A. Saturated Heterocyclic Compounds
202
B. Heteroaromatic Compounds
203
IV. Sulfonium Compounds
204
A. Natural Occurrence and Chemistry
204
V. Metabolism and Enzymology of Onium Compounds
217
A. Energetics of the Onium Bond (Written in Collaboration with Dr.
J. Durell)
217
B. Transfer Reaction from an Onium Pole
221
C. Enzymatic Mechanisms in the Formation of the Onium Bond .
.
233
VI. Conclusions
236
References
236
I. General Introduction, Natural Distribution, and Chemical
Properties of Onium Compounds
Onium compounds* are widely but unevenly distributed in nature.
They occur most abundantly and in the greatest variety in marine invertebrates, fishes, and certain plants, while in microorganisms and in
vertebrates only a few compounds are found and in relatively small
amounts.
* Onium compounds are addition compounds to which "a definite structure can
be ascribed only on the basis of an extension of the simple valence theory." More
precisely they may be defined as "substances formed by an addition reaction, in
the course of which some atom increases its valence by one unit and, in doing so,
increases its formal charge algebraically by one unit" (1).
181