Recombinant Human Ribosomal Protein S16: Expression, Purification, Refolding, and Structural Stability

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N. M. Parakhnevitch, A. A. Malygin, and G. G. Karpova^*

Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, pr. Lavrentieva 8, 630090 Novosibirsk, Russia; fax: (3832) 33-3677; E-mail: karpova@niboch.nsc.ru

^* To whom correspondence should be addressed.

Received May 26, 2004; Revision received June 25, 2004

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The cDNA of human ribosomal protein S16 was cloned into the expression vector pET-15b. Large-scale production of the recombinant protein was carried out in E. coli cells and highly purified protein was isolated. A method for refolding the protein from inclusion bodies was optimized. The secondary structure content of the refolded protein was analyzed by CD spectroscopy. It was found that 21 ± 4% of the amino acid sequence of the protein forms alpha-helices and 24 ± 3% is in beta-strands. The protein structure stability was studied at various pH values and urea concentrations. The protein is quickly denatured at pH above 8.0, whereas increasing of urea concentration causes slow unfolding of the protein.

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KEY WORDS: human ribosomal protein S16, expression, refolding

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