title: Orientating lipase molecules through surface chemical control for enhanced activity: A QCM-D and ToF-SIMS investigation.
abstract: Bio-active materials consisting of lipase encapsulated within porous silica particles were engineered to control the adsorption kinetics and molecular orientation of lipase, which play critical roles in the digestion kinetics of triglycerides. The adsorption kinetics of Candida antartica lipase A (CalA) was monitored using quartz crystal microbalance with dissipation (QCM-D) and controlled by altering the hydrophobicity of a silica binding support. The extent of adsorption was 2-fold greater when CalA was adsorbed onto hydrophobic silica compared to hydrophilic silica. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) fragmentation patterns, in conjunction with multivariate statistics, demonstrated enhanced exposure of the lipase's catalytic domain, specifically the histidine group responsible for activity, when CalA was adsorbed on hydrophilic silica. Consequently, lipid digestion kinetics were enhanced when CalA was loaded in hydrophilic porous silica particles, i.e., a 2-fold increase in the pseudo-first-order rate constant for digestion when compared to free lipase. In contrast, digestion kinetics were inhibited when CalA was hosted in hydrophobic porous silica, i.e., a 5-fold decrease in pseudo-first-order rate constant for digestion when compared to free lipase. These findings provide valuable insights into the mechanism of lipase action which can be exploited to develop smarter food and drug delivery systems consisting of porous lipid-based materials.
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, City East Campus, Adelaide, South Australia 5001, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Joyce
authors.affiliation: Future Industries Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, South Australia 5095, Australia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kempson
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, City East Campus, Adelaide, South Australia 5001, Australia. Electronic address: clive.prestidge@unisa.edu.au.
authors.forename: Clive A
authors.initials: CA
authors.lastname: Prestidge
mesh_terms: D000327:Adsorption; D002175:Candida / Q000737:chemistry / Q000201:enzymology; D020134:Catalytic Domain; D004339:Drug Compounding; D016503:Drug Delivery Systems; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D006639:Histidine / Q000737:chemistry; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008049:Lipase / Q000737:chemistry* / Q000302:isolation & purification; D016062:Porosity; D058525:Quartz Crystal Microbalance Techniques; D012822:Silicon Dioxide / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013499:Surface Properties; D014280:Triglycerides / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D014280:Triglycerides; D006639:Histidine; D012822:Silicon Dioxide; D008049:Lipase
keywords: Lipase; Lipid digestion; Porous silica; QCM-D; Surface chemistry; ToF-SIMS