L-asparaginase recovery through supported ionic liquid materials based on silica

Abstract

Acute lymphoblastic leukemia (ALL) accounts with approximately 6500 new cases in the United States each year [1]. The first-line biopharmaceutical being used to treat ALL, Oncaspar, is based on L-asparaginase (LA), with annual sales of approximately USD $100 million [2]. The main problem related to the therapeutic use of LA is the difficulty in its purification, accounting for up to 80% of total production costs [3]. Therefore, it is crucial to find new strategies to purify LA in order to decrease its current cost and allow its routinely use by a widespread population. Supported ionic liquid materials based on silica (SILs) are reported in the literature for the separation of natural compounds from vegetable biomass [4]. Although SILs represent a class of materials with high potential in protein purification, this specific application has been scarcely considered [5]. In this work, the search for SILs able to establish (non-covalent) specific interactions with LA, which subsequently allow its purification from the fermentation broth in which it is produced, was studied. In a first set of experiments, commercial LA was used in order to understand the adsorption behaviour of the enzyme onto SILs. Experimental conditions, such as pH, contact time and SILs/LA ratio were evaluated and optimized in what concerns the LA recovery yield. LA activity was assessed by the Nessler reaction, which quantifies the amount of ammonium released after the enzymatic reaction [6]. The results show that the ideal conditions for LA are pH 8 and a contact time with SILs of 30 min. With the envisioned strategy, process costs, energy consumed, and waste generated, can be considerably reduced, which can lead to the LA cost decrease and wider application. Further investigations on the purification of LA from the fermentation broth are ongoing.