Letters

The liver’s carbon fixation
The possibility that insects can harness solar energy (SN: 1/15/11, p. 8) is no less fascinating than the ability of the mammalian liver to do the light-independent part of photosynthesis: carbon fixation. When concentrations of the amino acid methionine rise after a high-protein meal, the liver shifts gears to get rid of the excess via activation of a specific transmethylation pathway requiring the amino acid glycine as a methyl acceptor.