Effect of osmolytes on the activity of anti-cancer enzyme L-Asparaginase II from Erwinia chrysanthemi

L-asparaginase is used for the treatment of acute lymphoblastic leukaemia (ALL); however, its formulation presents drawbacks such as a lack of stability and formation of aggregates. Osmolytes are small molecules accumulated by cells in response to environmental stresses and present a protective behaviour, favouring the equilibrium of macromolecules towards the native conformation. Therefore, osmolytes are employed as excipients in pharmaceutical protein formulations. Herein, recombinant L-ASNase II from Erwinia chrysanthemi (ErA II) was analysed with respect to the effect of osmolytes on kinetic and stability of this biopharmaceutical. The aggregation profiles were analysed trough nanotracking particle analysis and dynamic light scattering. The majority of the tested osmolytes increased ErA II specific activity and stability, being more pronounced for sucrose and sorbitol, which increased almost 70% of ErA II activity. The polyol preserved total enzyme activity for 30 days while sucrose preserved 81.1 ± 5.3% total enzyme activity over this period. Each osmolyte resulted in a specific aggregation profile and the presence of sucrose or sorbitol resulted in a lower quantity of aggregates in the range of 100–300 nm. The present findings may contribute to the improvement of adjuvants in L-ASNase formulations and the optimization of other biopharmaceutical formulations.publishe

Interrelationship between partition behavior of organic compounds and proteins in aqueous dextran-Polyethylene glycol and Polyethylene glycol-sodium sulfate two-phase systems

Partition behavior of adenosine and guanine mononucleotides was examined in aqueous dextran-polyethylene glycol (PEG) and PEG-sodium sulfate two-phase systems. The partition coefficients for each series of mononucleotides were analyzed as a functions of the number of phosphate groups and found to be dependent on the nature of nucleic base and on the type of \ATPS\ utilized. It was concluded that an average contribution of a phosphate group into logarithm of partition coefficient of a mononucleotide cannot be used to estimate the difference between the electrostatic properties of the coexisting phases of ATPS. The data obtained in this study were considered together with those for other organic compounds and proteins reported previously, and the linear interrelationship between logarithms of partition coefficients in dextran-PEG, PEG-Na2SO4 and PEG-Na2SO4-0.215 M NaCl (all in 0.01 M Na- or K/Na-phosphate buffer, pH 7.4 or 6.8) was established. Similar relationship was found for the previously reported data for proteins in Dex-PEG, PEG-600-Na2SO4, and PEG-8000-Na2SO4 ATPS. It is suggested that the linear relationships of the kind established in \ATPS\ may be observed for biological properties of compounds as well.Nuno da Silva acknowledges the financial support by Fundação para a Ciência e a Tecnologia (FCT) of the Portuguese’s Ministry for Science, Technology and Higher Education, in the framework of the Operational Program COMPETE (PTDC/EQU-FTT/120332/2010). Pedro P. Madeira acknowledges the financial support in part provided by (i) FCT/MEC and FEDER through COMPETE 2020 (Project UID/EQU/50020/2013-POCI-01-0145-FEDER-006984) and (ii) QREN, FCT, ON2 and FEDER, through COMPETE (Project NORTE-07-0124-FEDER-0000011