Thursday, April 29, 2010

Phosphates in Life

Since I was just discussing phosphorous, this quick article is relevant. It also points out an intriguing paradox of how life uses phosphorous.

In DNA (and RNA), all the attention is focused on the bases, (adenine, cytosine, guanine and thymine, the A, C, G and T) that create the "code of life". The hydrogen bonding that occurs between the A and the T, and the C and the G is at the heart of the double helix. However, these bases are all attached to a phosphate, and each phosphate is attached to another. These phosphates are the polymer backbone of DNA - the bases are just moieties. And as become more apparent with each passing year as new discoveries are announced of prehistoric DNA being recovered from ______________, these phosphate chains are extremely stable.

At the same time, phosphates are also used in energizing life. As adenosine triphosphate and adenosine disphophate are interconverted, energy is given and taken away from the cell, a reaction that happens extremely quickly, in contrast to the stability of the phosphate backbone of DNA.

"Why Nature Chose Phosphates" from Science in 1987 (open access) also has another perspective on why phosphates are heavily used in biochemistry, far more than in most organic chemistry. (Are there even any commercially available synthetic polymers with a phosphorus backbone?)


Anonymous said...

The backbone of a DNA is a sugar-phosphate chain. The bases are directly attached to the sugar, not the phosphate.

John said...

And that's why I'm not a biochemist! Thanks for the catch.