TAILIEUCHUNG - Báo cáo khoa học: Chaperone and antichaperone activities of trigger factor

Reduced denatured lysozyme tends to aggregate at neutral pH and competition between productive folding and aggregation substantially reduces the efficiency of refolding. Trigger factor, a folding catalyst and chaperone can, depending on the concentration of trigger factor and the solution conditions, cause either a substantial increase (chaperoneactivity) or a substantial decrease (antichaperone activity) in the recoveryof native lysozymeas comparedwith spontaneous refolding. | Eur. J. Biochem. 269 4516-4523 2002 FEBS 2002 doi Chaperone and antichaperone activities of trigger factor Guo-Chang Huang Jia-Jia Chen Chuan-Peng Liu and Jun-Mei Zhou National Laboratory of Biomacromolecules Institute of Biophysics Academia Sinica Beijing China Reduced denatured lysozyme tends to aggregate at neutral pH and competition between productive folding and aggregation substantially reduces the efficiency of refolding. Trigger factor a folding catalyst and chaperone can depending on the concentration of trigger factor and the solution conditions cause either a substantial increase chaperone activity or a substantial decrease antichaperone activity in the recovery of native lysozyme as compared with spontaneous refolding. When trigger factor is working as a chaperone the reactivation rates of lysozyme are decelerated and aggregation decreases with increasing trigger factor concentrations. Under conditions where antichaperone activity of trigger factor dominates the reactivation rates of lysozyme are accelerated and aggregation is increased. Trigger factor and lysozyme were both released from the aggregates on re-solubilization with urea indicating that trigger factor participates directly in aggregate formation and is incorporated into the aggregates. The apparently dual effect of trigger factor toward refolding of lysozyme is a consequence of the peptide binding ability and may be important in regulation of protein biosynthesis. Keywords chaperone antichaperone protein folding trigger factor. Molecular chaperones assist protein folding by binding unfolded or misfolded chains and preventing or reversing misfolding or aggregation 1 . However in certain cases chaperones may also be involved in formation of aggregates 2-6 . This so-called antichaprone activity or incitement to aggregate by a molecular chaperone has been studied in most detail for protein disulfide isomerase PDI 7-11 . With aggregation-prone substrates and at .

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