The purification and identification of human blood serum proteins with affinity to the antitumor active RL2 lactaptin using magnetic microparticles

Abstract

The cytopoxic effect of RL2 lactaptin (the recombinant analog of proteolytic fragment of human kappa‐casein) toward tumor cells in vitro and in vivo presents it as a novel promising antitumor drug. The binding of any drug with serum proteins can affect their activity, distribution, rate of excretion and toxicity in the human body. Here, we studied the ability of RL2 to bind to various blood serum proteins. Using magnetic microparticles bearing by RL2 as an affinity matrix, in combination with mass spectrometry and western blot analysis, we found a number of blood serum proteins possessing affinity for RL2. Among them IgA, IgM and IgG subclasses of immunoglobulins, apolipoprotein A1 and various cortactin isoforms were identified. This data suggests that in the bloodstream RL2 lactaptin takes part in complicate protein–protein interactions, which can affect its activity.

Isolation and identification in human blood serum of the proteins possessing the ability to bind with 48 kDa form of unconventional myosin 1c and their possible diagnostic and prognostic value

“…Previously, we used novel monodisperse magnetic poly(glycidyl methacrylate) (mag‐PGMA–NH 2 ) microspheres bearing 48/Myo1C, which allowed us to detect IgM and IgG immunoglobulins in blood serum of patients with multiple sclerosis, while other proteins remained uncharacterized (Zasońska et al, 2018). A separation of the desired protein when using the affinity chromatography relies on the reversible interactions between the protein to be purified and the affinity ligand coupled to the chromatographic matrix (Manko et al, 2019). Most proteins possess an inherent recognition site which can be used for selection of the appropriate affinity ligand.…”

Identification of cortactin molecular forms in human urine and their possible diagnostic value

“…In our opinion, there are two ways of their appearance in human urine. Recently, we discovered for the first time in human blood serum three polypeptides with molecular weights of 200, 55, and 28 kDa with immunoreactivity against monospecific anti-cortactin antibodies [15]. Consequently, there is a possibility that urinary cortactin molecular forms can originate from blood serum.…”