Abstract
Arginine auxotrophy is a metabolic defect that renders tumor cells vulnerable towards arginine-depleting substances, such as arginine deiminase (ADI) from Streptococcus pyogenes (SpyADI). Previously, we confirmed SpyADI susceptibility on patient-derived glioblastoma multiforme (GBM) models in vitro and in vivo. For application in patients, serum half-life of the enzyme has to be increased and immunogenicity needs to be reduced. For this purpose, we conjugated the S. pyogenes-derived SpyADI with 20 kDa polyethylene glycol (PEG20) moieties, achieving a PEGylation of seven to eight of the 26 accessible primary amines of the SpyADI. The PEGylation reduced the overall activity of the enzyme by about 50% without affecting the Michaelis constant for arginine. PEGylation did not increase serum stability of SpyADI in vitro, but led to a longer-lasting reduction of plasma arginine levels in mice. Furthermore, SpyADI-PEG20 showed a higher antitumoral capacity towards GBM cells in vitro than the native enzyme.Key points• PEGylation has no effect on the affinity of SpyADI for arginine• PEGylation increases the antitumoral effects of SpyADI on GBM in vitro• PEGylation prolongs plasma arginine depletion by SpyADI in mice
Highlights
Arginine is a semi-essential amino acid required for the biosynthesis of proteins, polyamines, creatinine, and nitric oxides
Overall specific activity of SpyADI was reduced by PEGylation, the binding affinity of the enzyme to arginine was not significantly affected, as Michaelis–Menten kinetics with the specific activity of the enzyme as a function of the arginine concentration revealed Michaelis constants (Km) of 0.94 ± 0.3 and 1.04 ± 0.3 mM arginine for native and PEGylated SpyADI, respectively (Fig. 3)
We analyzed the efficiency of arginine depletion of native SpyADI and SpyADI-PEG20 in vitro
Summary
Arginine is a semi-essential amino acid required for the biosynthesis of proteins, polyamines, creatinine, and nitric oxides. The availability of arginine is important for a variety of biological pathways, e.g., cell growth, proliferation, and survival (Delage et al 2012; Husson et al 2003; Morris 2004, 2009; Riess et al 2018; Wu et al 2009; Wu and Morris 1998). Human cells obtain arginine either from extracellular or intracellular sources. Extracellular arginine is taken up into the cell via solute carrier proteins (SLC) (Fultang et al 2016). Arginine is obtained by proteolytic degradation and arginine de novo synthesis in the urea cycle. It has been observed that cancer cells frequently downregulate non-essential biosynthesis pathways to allow faster growth with smaller energy expenditure
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
