January 13, 2013
New Ribosome-Inspired Molecular Machine Developed
redOrbit Staff & Wire Reports — Your Universe Online
The nanomachine, which is only a few millionths of a millimeter long, was constructed by professor David Leigh of the university´s School of Chemistry, and in a statement, the institute called it “the most advanced molecular machine of its type.”
Leigh also compared the process to the way robotic assembly lines operate in automotive plants, and said it could ultimately help make the manufacturing of molecules “much more efficient and cost effective.” A paper detailing the development of the machine has been published in the journal Science.
According to Nature´s Mark Peplow, Leigh´s machine is much simpler than the ribosome, only about one-tenth of its size, and far slower. It also destroys all of the code it reads and is only able to create very small bits of protein (also known as peptides), but Leigh believes it could be used for a number of different purposes.
“Ribosomes make proteins, which are just one type of polymer used by nature. In fact, all of biology is based on just four sorts of so-called information polymers — proteins, DNA, RNA and also carbohydrates. But with our artificial machines, we're not limited by the same building blocks of nature,” the professor told BBC News. “So, we should be able to make new materials with other types of building blocks - new types of plastics, new types of catalysts, pharmaceuticals and so on.”
The method used with the nanomachine requires a large molecular ring (also known as a rotaxane), which is threaded into another molecule, which acts like an axle. This axle is lined with three amino acids, and a chain of three more hang from the ring´s outer edge.
One of the attached amino acids is cysteine, which Peplow reports includes a crucial sulfur-containing thiol group. When the system is heated, the thiol group snatches an amino acid from the axle and transfers it to the end of the attached chain of amino acids.
“The ring can then move along the axle and repeat the same trick with the next two amino acids. Unthreading the ring and breaking off the newly-formed chain delivers a perfectly formed peptide made from all six amino acids,” he added. Although Leigh´s rotaxane mimics the ribosome in its sequential building of peptides, the sulphur-assisted amino acid transfer is found elsewhere in biology: some bacteria rely on it to synthesize proteins. It has also become a standard technique in laboratory protein synthesis.”
Currently, simultaneously running a massive number of these machines (10^18) at the same time can produce approximately more than 10 milligrams of peptide, Peplow said. The process takes roughly 12 hours to attach each amino acid in the sequence, compared to a rate of up to 20 amino acids per second in the ribosome. Still, even though the research is not as efficient as its natural rival, it has promise.
“The next step,” Leigh says, “is to start using the machine to make sophisticated molecules with more building blocks. The potential is for it to be able to make molecules that have never been seen before. They´re not made in nature and can´t be made synthetically because of the processes currently used. This is a very exciting possibility for the future.”