Effects of Osmolytes on Unfolding of Chicken Liver Fatty Acid Synthase

Y.-D. Park¹, B.-N. Wu², W.-X. Tian², and H.-M. Zhou^1,3*

¹Department of Biological Science and Biotechnology, School of Life Science and Engineering, Tsinghua University, Beijing 100084, P. R. China; fax: +8610 62772245; E-mail: zhm-dbs@mail.tsinghua.edu.cn

²Graduate School, Chinese Academy of Sciences, Beijing 100039, P. R. China

³Protein Science Laboratory of the Ministry of Education, School of Life Science and Engineering, Tsinghua University, Beijing 100084, P. R. China

^* To whom correspondence should be addressed.

Received May 29, 2001; Revision received October 28, 2001

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Urea-induced aggregation of chicken liver fatty acid synthase [acyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing and thioester-hydrolyzing), EC 2.3.1.85] was studied. The aggregation was facilitated at increased ionic strength. Methyl-beta-cyclodextrin and some osmolytes, such as glycerol, sucrose, proline, glycine, and heparin, could effectively prevent the aggregation, implying an artificial chaperone role of those substances during fatty acid synthase unfolding. The osmolytes also protected the enzyme from inactivation.

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KEY WORDS: fatty acid synthase, urea denaturation, aggregation, osmolyte, artificial chaperone

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