Isolation and Characterization of a Low-Molecular-Weight Immunoglobulin-Binding Protein from Yersinia pseudotuberculosis

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E. V. Sidorin^*, N. Yu. Kim, E. V. Leichenko, S. D. Anastyuk, P. S. Dmitrenok, G. A. Naberezhnykh, and T. F. Solov'eva

Pacific Institute of Bioorganic Chemistry, Far-Eastern Division, Russian Academy of Sciences, pr. 100-letiya Vladivostoka 159, 690022 Vladivostok, Russia; fax: (4232) 314-050; E-mail: sev1972@mail.ru

^* To whom correspondence should be addressed.

Received May 31, 2006; Revision received July 6, 2006

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A low-molecular-weight immunoglobulin-binding protein (IBP) bound with the cell envelope has been isolated from Yersinia pseudotuberculosis cells and partially characterized. This IBP is a hydrophilic protein with a high polarity index of 55.3%. The molecular weight of the protein has been determined by MALDI-TOF mass spectrometry as 14.3 kD. CD spectroscopy showed that the IBP has high contents of the beta-structure and random coil structure. The IBP contains glycine as the N-terminal amino acid. The protein can be stored for a long time at acidic pH values but aggregates and loses activity at alkaline and neutral pH. The IBP binds rabbit IgG with optimum at pH of 6.0-7.5. The IBP interacts with IgG molecule in the Fc-fragment region. The protein retains activity after heating at 100°C in the presence of SDS.

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KEY WORDS: immunoglobulin G, Fc-fragment of IgG, immunoglobulin-binding protein

DOI: 10.1134/S0006297906110149

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