Preliminary Studies with L-Asparaginase Bound to Implantable Bovine Collagen Heterografts: A Potential Long-Term, Sustained Dosage, Antitumor Enzyme Therapy System

Abstract

In this study, L-Asparaginase has been bound to collagen heterografts derived from carotid bovine arteries. The immobilization procedure utilizes both non-covalent and covalent interactions to fix the enzyme. Binding of the enzyme to the graft material was shown to the pH dependent, with optimum binding occurring at pH 6.0 and pH 8.5. Amidohydrolysis by the bound enzyme exhibited zero-order kinetic behavior at substrate saturating conditions. Total apparent asparaginase activity expressed by the grafts as a function of the number of repeated in vitro assay trials demonstrated that over a span of 3 months of intermittent storage and use, the enzyme-grafts retained as much as 62% of their initial activities. Implantation of 4 asparaginase-collagen grafts in various locations of the thoracic and abdominal aorta resulting in prolonged reductions of plasma asparagine levels in 3 of the 4 implants. Presence of plasma asparaginase was checked in one of the four implants and determined to be less than 2 X 10(-4) I.U./ml. Removal of grafts from 3 of the 4 animal subjects showed reductions in the apparent asparaginase activity expressed by the grafts of 7 to 70 percent after in vivo contact times which varied from 6 to 15 days.

Synthesis of silk sericin peptides–L‐asparaginase bioconjugates and their characterization

“…The modification or immobilization of the enzyme not only reduced its immunity and toxicity to humans but also greatly improved its resistance to proteolysis in comparison with native ASNase. Some attempts have been made to prepare insoluble, matrix‐supports for ASNase immobilization, such as collagen,5 CM‐cellulose,6 polyacrylamide,7 poly (2‐hydroxyethyl methacrylate) gels,8, 9 and PEG–BSA hydrogels 10. This type of derivative may be appropriate for extracorporeal devices in the clinical treatment of ALL.…”

Enhanced stability of L‐asparaginase by its bioconjugation to poly(styrene‐co‐maleic acid) and Ecoflex nanoparticles

“…One of the methods for L‐ASNase immobilisation is physical adsorption on the surface of carriers. In this paper, insoluble matrix supports have been used for enzyme immobilisation such as carboxymethyl cellulose [7], collagen [8], poly(2‐hydroxyethyl methacrylate) gels, polyacrylamide [9, 10], and polyethylene glycol and bovine serum albumin hydrogels [11]. Another way for enzyme immobilisation is physical trapping the enzyme in liposomes [12].…”

Comparison of Free and Immobilized L-asparaginase Synthesized by Gamma-Irradiated Penicillium cyclopium

“…It has been reported that the immobilized enzyme not only reduces toxicity, but also greatly improved resistance to proteolysis compared to native L-asparaginase (Zhang et al, 2004;Ghosha et al, 2011). Attempts were made for the preparation of insoluble matrix supports such as collagen (Jefferies et al, 1977), carboxy methyl cellulose (Hasselberger et al, 1970), polyacrylamide and poly (2-hydroxyethyl methacrylate) gels (O'Driscoll et al, 1975) derivatives bioconjucated with L-asparaginase for use in cancer therapy. That said, enzyme immobilization has attracted great interest by chemists and biochemists for its wide application in academic research and industrial processes (Mahmoud and Helmy, 2009;Shafei et al, 2015).…”