ananyo writes "The ribosome, the molecular machine that translates our genetic code to build the body's proteins, is a mechanical marvel. Now, chemists have invented a nanomachine that can achieve a similar feat. The artificial system is not about to displace nature's ribosome, a complex of proteins and RNA. It is much simpler, and only about about one-tenth of the size — and, it is achingly slow, destroys the code it reads and can produce only very short chunks of protein, known as peptides. It does, however, show that some of the tactics of biology's molecular machines can be adopted to make useful chemicals. The device relies on a rotaxane — a large molecular ring threaded onto another molecule that acts as an axle (abstract). The axle is lined with three amino acids, and a chain of three more amino acids hangs from the outer edge of the ring. Heating the device prompts the ring to move along the axle, adding amino acids one-by-one to the chain attached to the ring."