โ Scribed by Harold J. Morowitz
No coin nor oath required. For personal study only.
t was a sunny summer afternoon and I found myself browsing in ''Biochemistry, The Chemical Reactions of Living Cells,'' an encyclopedic two-volume text by David Metzler. I came across the following startling sentence on page 1244. ''One of these compounds, bacteriohopanetetrol, may be one of the most abundant compounds on the earth.'' The challenge of this sentence led me to an article ''Prokaryotic Hopanoids and Other Polyterpenoid Sterol Surrogates'' by Guy Ourisson, Michel Rohmer, and Karl Poralla (Annual Reviews of Microbiology, 1987). Here, I came to a more startling thought.
''These classes of lipids are biologically essential and extremely widespread . . .. Their most extraordinary character is the fact that they were not found earlier. They probably form the most abundant class of moderately complex organic substances on earth, if we include their fossils. The fossil hopanoids alone contain at least as much organic carbon as all the living animal, plant, and microorganism (about one trillion tons of reduced carbon).
My next step was to query a number of distinguished scientists I was in contact with. To a person, they were unfamiliar with bacteriohopanetetrol. I turned to Google for solace and got only 538 hits. So few hits, and for one of the planet's most abundant organic molecules seems strange indeed. I calculated 1.86 billion metric tons per Google hit, a shocking measure of being ignored. I decided to establish a unit of being ignored by the scientific community. It is one metric ton per Google hit and I shall name it the ourisson in honor of Guy Ourisson whose work on hopanoids was long passed over by the scientific community.
What then is the biological role of bacteriohopane tetrol? These molecules appear to be a universal membrane component in all members of the super taxon bacteria. They act as membrane stiffeners playing the same role in bacteria as cholesterol in animals, sitosterol in plants, and ergosterol in fungi. Archaea seem
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