Nucleation-condensation model
The nucleation-condensation model ( English : nucleation-condensation model ) is a scientifically accepted model to explain the protein folding . The model explains protein folding via unstable transition states. The problem can be illustrated with the help of a half denatured protein solution. It leads to the assumption that the protein should be folded in half, but this is not the case. The solution would contain half fully folded and half unfolded protein molecules. From this one would infer that a protein occurs only folded or unfolded, but at the molecular level this is impossible. Unstable transition states must exist between the denatured and the native (structured or biologically functional) state.
The starting point of the model is the formation of a protein core (nucleus) as an unstable transition state, starting from the denatured state. Certain areas with a certain tendency to structure adopt these structures first. Together, these structures form a nucleus that is similar to the native state, but still contains flexible structures. This nucleus, which has yet to be formed, is stabilized by extensive interactions so that the nucleus can expand. The stabilization of the nucleus takes place so quickly that it cannot be completely converted into the transition state. In order to compensate for this, the nucleation is also coupled with the condensation. This means that the flexible structures condense completely and form the solid, native structure.
The model shows that certain folding paths can be preferred. When transitioning from denatured to native protein, the protein follows a general path (i.e. the transition states represent a collection of similar structures) and not a specific path. The energetic sequence for the protein folding process can be demonstrated in a folding funnel.
literature
- Jeremy M. Berg, Lubert Stryer , John L. Tymoczko: Stryer Biochemistry. Springer-Verlag, Berlin, Heidelberg 2014, ISBN 978-3-8274-2989-6 .
Individual evidence
- ^ IE Sanchez: Protein folding transition states probed by loop extension . In: Protein Science . 17, No. 1, 2007, ISSN 0961-8368 , pp. 183-186. doi : 10.1110 / ps.073217708 . .
- ↑ AR Fersht, V. Daggett: Protein folding and unfolding at atomic resolution. In: Cell. Volume 108, Number 4, February 2002, pp. 573-582, PMID 11909527 (review).
- ↑ Unnati Ahluwalia, Nidhi Katyal, Shashank Deep: Models of protein folding . In: Journal of Proteins and Proteomics . 3, No. 2, July – December 2012, pp. 85–93.