Effect of Triton X-100 on the Activity and Selectivity of Lipase Immobilized on Chemically Reduced Graphene Oxides

Abstract

The effect of support hydrophobicity on lipase activity and substrate selectivity was investigated with and without Triton X-100 (TX-100). Lipases from Thermomyces lanuginosa (TL) and Alcaligenes sp. (QLM) were immobilized on graphene oxide (GO) and a range of chemically reduced graphene oxides (CRGOs) with different levels of surface hydrophobicity. Activity assays using 4hydroxy-N-propyl-1,8-naphthalimide (NAP) esters of varying chain lengths (NAPbutyrate (NAP-B), NAP-octanoate (NAP-O), and NAP-palmitate (NAP-P)) showed that the activity of immobilized QLM and TL decreased by more than 60% on GO and 80% on CRGO (2 h), with activity decreasing further as surface hydrophobicity of the CRGOs increased. Across the hydrophobicity range of GO/ CRGOs, the substrate selectivity of QLM shifted from more readily hydrolyzing NAP-P to NAP-B, while TL retained its substrate selectivity for NAP-O. Lipase TL was also shown to desorb from GO and 2 h CRGO when mixed with NAP-O and NAP-P, whereas QLM did not. Circular dichroism analyses of the lipase α-helix content correlate to the observed activity data, with decreases in the α-helical content (40% in TL and 20% in QLM relative to free lipase) consistent with decreases in activity after immobilization on GO. α-Helical content decreased even further as the surface hydrophobicity of CRGOs increased. Attenuated total reflectance-Fourier transform infrared spectroscopy also showed significant changes to the lipase secondary structure upon immobilization. The addition of TX-100 into the activity assay modified the substrate selectivity of immobilized QLM, improving the activity against NAP-O (90%) and NAP-P (67%) compared to the activity measured without TX-100. It was shown that TX-100 primarily affected the activity of QLM by interacting with the ester substrate and the lipase itself. This study provides an improved understanding of how support hydrophobicity and the presence of TX-100 can affect activity/selectivity of lipases immobilized on hydrophobic supports.

Amphiphilic Nanointerface: Inducing the Interfacial Activation for Lipase

“…The literature reported that the free TL has a high α-helicity. , Circular dichroism showed an increase in the hydrophobicity of the carrier and a consequent decrease in the α-helix of lipase TL, with only a 20% reduction after fixation on the GO carrier . This indicates that the mild amphiphilic surface is relatively friendly to the structural effects of TL.…”

“…34,35 Circular dichroism showed an increase in the hydrophobicity of the carrier and a consequent decrease in the α-helix of lipase TL, with only a 20% reduction after fixation on the GO carrier. 36 This indicates that the mild amphiphilic surface is relatively friendly to the structural effects of TL. Studies have shown that low-intensity ultrasound's alteration of the secondary structure of lipase TL increases its catalytic activity; 37 therefore, appropriate conformational changes are beneficial for lipase activity.…”

Dynamic Compartmentalization of Peptide–Oligonucleotide Conjugates with Reversible Nanovesicle–Microdroplet Phase Transition Behaviors

“…Then, a weak hydrophobic interaction disruptor, 1,6-hexanediol (Hdo), was employed, 49 and it was found that the T t was increased from 27 to 32 °C after the addition of Hdo, indicating that the hydrophobic interactions were disturbed (Figure 3d). Finally, we used a nonionic surfactant, Triton X-100 (TX-100), 50 to destroy the strong hydrophobic interaction. The sELP−ONs failed to form droplets after 1% TX-100 was added (Figure 3d).…”

Synthesis of 3,4-dihydroxy-1,8-naphthalimides with inbuilt catechol and crown ether functionalities

“…22 In recent years, our focus has been on the preparation of 4-hydroxy-1,8-naphthalimides 23 and their use as biochemical reagents for determining lipase and esterase activity. 24,25 Recently, we developed a synthetic methodology to access 3,4-dialkoxy 1,8-naphthalimides, 17 which led to the preparation of the lipid droplet imaging probes DMN-LD and DMN-DT (Fig. 1).…”