Proteolytic Activity of IgG Antibodies from Blood of Acquired Immunodeficiency Syndrome Patients

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E. S. Odintsova¹, M. A. Kharitonova², A. G. Baranovskii¹, L. P. Sizyakina², V. N. Buneva¹, and G. A. Nevinsky^1*

¹Novosibirsk Institute of Chemical Biology and Fundamental Medicine, Siberian Division of the Russian Academy of Sciences, pr. Lavrentieva 8, 630090 Novosibirsk, Russia; fax: (3832) 333-677; E-mail: nevinsky@niboch.nsc.ru

²SII Clinical Immunology of Rostov-on-Don State Medical University, Nakhichevansky pr. 29, 344022 Rostov-on-Don, Russia

^* To whom correspondence should be addressed.

Received June 29, 2005; Revision received October 4, 2005

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Proteolytic activity of polyclonal IgG antibodies (Abs) from the blood of AIDS patients was analyzed for the first time. These Abs were shown to display higher activity in hydrolysis of beta-casein than in hydrolysis of human immunodeficiency virus (HIV)-1 reverse transcriptase (RT) or human serum albumin (HSA). Several abzymatic criteria were applied and it was shown that RT, HSA, and beta-casein hydrolyzing activities are an intrinsic property of polyclonal Abs from AIDS patients. Casein-hydrolyzing Abs were detected in the blood serum for 95% of AIDS patients, and it was shown that they possess serine protease-like catalytic activity. The substrate specificities of polyclonal Ab proteases and typical human proteases are different. Depending on the patient, the IgGs exhibit various pH optima of proteolytic activity. The products of casein hydrolysis by Ab proteases were different from those in the case of trypsin, chymotrypsin, and proteinase K.

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KEY WORDS: antibodies, natural abzymes, AIDS, proteolytic activity

DOI: 10.1134/S0006297906030047

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