Investigation of Conformational Changes Induced by Binding of Pancreatic RNase to Anti-RNase IgG Derived F_ab Monomer Using Optical Procedures

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H. Younus^1*, S. Jamal¹, B. Ahmad¹, and M. Saleemuddin^1,2

¹Interdisciplinary Biotechnology Unit and ²Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India; fax: +91-571-272-1776; E-mail: hinayounus@rediffmail.com; alg_btisamua@sancharnet.in

^* To whom correspondence should be addressed.

Received June 20, 2005; Revision received September 10, 2005

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The conformational changes induced in F_ab fragments of polyclonal anti-RNase antibody molecules obtained by digestion with papain as a result of binding of pancreatic RNase have been studied. The RNase-F_ab complex (RN-F_ab), being soluble, could be subjected to thermodynamic investigations using optical strategies, also because of the absence of tryptophan in RNase. Internalization of the chromophores (tryptophans and tyrosines) of F_ab occurs when it binds to RNase, suggesting an increase in the compactness of F_ab due to the binding of RNase.

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KEY WORDS: antigen-antibody complex, F_ab, RNase, conformational changes

DOI: 10.1134/S0006297906020155

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