Comparison of enzymatic properties of DNA-abzymes and human DNAses

Highly specific novel method for isolation and purification of lupus anti-DNA antibody via oligo-(dT) magnetic beads

A novel method for isolation and purification of anti-ssDNA antibodies from human sera is developed. The process involves: antibody purification based on their affinity for single-stranded sequence of thymidines and removal of remaining components via protein G coated magnetic beads, with high affinity for only IgG subclass. The high degree of purity and molecular weights of healthy versus lupus anti-ssDNA antibodies were confirmed by SDS-PAGE and silver staining. Western blot confirmed IgG isotype. This novel technique allows for diagnostic purposes, structural and functional analysis of anti-DNA antibodies, and studies of their role in autoimmune diseases.

Proteolytic activity of IgG antibodies from blood of acquired immunodeficiency syndrome patients

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.