| Chemical Inventory |  | Sample Tracking |  | E-Laboratory Notebooks |  | MSDS Management |  | Chemical Drawing |  | Molecular Modeling Drawing |

ARE PROTEIN FOLDING INTERMEDIATES CAUSED BY TRANSIENT AGGREGATION ? Maria Silow, Avd. för Biokemi Ideon G2:G Sölvegatan 41 223 63 Lund Mia Silow and Mikael Oliveberg, Biochemistry, Chemical Centre, BOX 124, S-221 00 Lund, Sweden. e-mail: mikael.oliveberg@biochem.lu.se Recently some small globular proteins have been found to fold directly into their native conformations in a two-state process without populated intermediates. The findings question the role of intermediates and point at the possibility that partly structured states are misfolds trapped in non-productive pathways. We report here that the spliceosomal protein U1A, which exhibits a classical three-state folding behaviour, has an intermediate which is caused by transient aggregation of denatured protein. The aggregation behaviour is reflected in a concentration dependence of the refolding amplitudes. At low concentrations of protein, U1A folds in a two-state process directly from the denatured monomer whereas at high concentrations of protein the observed refolding takes place from an aggregate which is formed in the dead-time of the stopped-flow instrument. Is transient aggregation a general problem in time resolved folding studies or a unique feature of the polypeptide of U! 1A ? ## Back to the list of abstracts