Russ Abbott wrote circa 10-12-02 03:04 PM: > This (from another > article<http://www.the-scientist.com/news/display/57851/#ixzz16zxXUGXe>) > looks like a significant part of the answer. > [...] > In fact, its similarity to phosphorus and its instability partly explains > why arsenic is so toxic. The body may not be able to distinguish between > phosphate -- the most common form of phosphorus in organisms -- and its > arsenic equivalent, arsenate. As a result, scientists suspect that arsenate > can be incorporated into molecules and pathways that normally use phosphate, > causing downstream processes to fail if the arsenate molecules are quick to > break down or otherwise don't work properly.
I think this block of text from the original article is more indicative of the importance[*] of the find: "Although AsO_4^3- esters are predicted to be orders of magnitude less stable than PO_4^3- esters, at least for simple molecules (8), GFAJ-1 can cope with this instability. The vacuole-like regions observed in GFAJ-1 cells when growing under +As/-P conditions are potentially poly-β- hydroxybutyrate rich [as shown in other Halomonas species (19)] which may stabilize As(V)-O-C type structures because non-aqueous environments appear to promote slower hydrolysis rates for related compounds (8). We propose that intracellular regions or mechanisms that exclude water may also promote this stability." The keyword being "non-aqueous". [*] FWIW, I find it odd for you to ask, of this particular article, "why is this important?" Of all the obscure, mumbo-jumbo journal articles out there (our discussion of PoMo aside ;-), it seems blatantly obvious to me that the substitution of As for P in DNA is important, even if we don't know what the implications are. I am woefully ignorant of the literature, though. Is it fairly common to find and report substitutes for DNA components? -- glen e. p. ropella, 971-222-9095, http://tempusdictum.com ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org