In regard to the letter from John D. Sutherland on bacteria that tolerate arsenic, either we have another “polywater” or “cold fusion” controversy or perhaps after 50-plus years we still do not know everything there is to know about DNA and the bonding strength of phosphorus versus arsenic in such a structure (C&EN, Dec. 13, 2010, page 4). After more than 50 years of studying and applying chemistry in my career, I am still amazed by the “theories” we accept as fact that get blown apart by further study. Then everyone jumps on the bandwagon to claim the “new theory” should have been obvious.
Some scientists think arsenic could substitute for phosphorus and function in the same manner as phosphorus in the proteins, metabolites, and DNA of living organisms (C&EN, Dec. 6, 2010, page 36). If the available facts are to advance science, all observation must be either for or against your hypothesis. Since there has been no effort to test the validity and generality of the hypothesis, we must ask the question: What experiment could disprove your hypothesis that arsenic can function in the living organism in the same manner as phosphorus?
I predict that the more you substitute arsenic compounds for phosphorus compounds in major metabolites such as glucose-6-phosphate, the more you will find the living organism is no longer alive. The reason is simple: Arsenic-containing compounds cannot function in the living organism in the same manner as phosphorus-containing compounds. Science advances only by disproving some empty hypothesis or theory. If I am right, these preliminary observations must be retracted.
James W. Flesher