These molecular solipsists could make big contributions to science--in spite of themselves.

Inteins aren't what you'd call "helping enzymes." In other words, they don't assist other proteins in the reactions that transform them from their primary states into the protein complexes that enable them to perform their unique biological functions. Instead, they remove themselves entirely from the proteins of which they are components--and then splice the remaining parts together to form a whole molecule.

"You can think of a protein as a kind of ribbon," says Phil Shemella, a graduate student in the department of physics at Rensselaer Polytechnic Institute. "At two locations, the ribbon is cut, and the middle--the intein--falls away." These inteins are autocatalytic--they already contain the enzyme necessary to accomplish the cleaving and splicing that forms the new protein structure.

"We sometimes call them 'selfish proteins,' or 'selfish DNA,'" says Saroj Nayak, an assistant professor of physics at RPI. Nayak is Shemella's advisor and a principal investigator in a multidiscplinary investigation into why inteins behave the way they do. "Inteins are by themselves--they don't care about the rest of the physical area, they don't need anything else, they're entirely self-contained."

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