TY - JOUR
T1 - Enhanced activity of horseradish peroxidase in Langmuir-Blodgett films of phospholipids
AU - Schmidt, Thais F.
AU - Caseli, Luciano
AU - Viitala, Tapani
AU - Oliveira, Osvaldo N.
N1 - Funding Information:
The authors are grateful to FAPESP, CNPq, Rede Biomat and IMMP/MCT (Brazil) for the financial assistance.
PY - 2008/10
Y1 - 2008/10
N2 - The immobilization of enzymes in nanostructured films has potential applications, e.g. in biosensing, for which the activity may not only be preserved, but also enhanced if optimized conditions are identified. Optimization is not straightforward because several requirements must be fulfilled, including a suitable matrix and film-forming technique. In this study, we show that horseradish peroxidase (HRP) has its activity enhanced when immobilized in Langmuir-Blodgett (LB) films, in conjunction with dipalmitoylphosphatidylglycerol (DPPG). Incorporation of HRP into a DPPG monolayer at the air-water interface was demonstrated with compression isotherms, and Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS). From the PM-IRRAS data, we inferred that HRP was not denatured when adsorbed on a pre-formed, low pressure DPPG monolayer. A change in orientation was induced by the phospholipid matrix, with the amide C{double bond, short}O and NH groups from HRP being oriented perpendicular to the surface, parallel to the DPPG acyl chains, i.e. the α-helix was inserted into the monolayer. The mixed DPPG-HRP monolayer could be transferred onto solid supports, to which HRP activity was ca. 23% higher than in solution. The control of molecular architecture and choice of a suitable phospholipid matrix allowed HRP-containing LB films to be used in sensing peroxide.
AB - The immobilization of enzymes in nanostructured films has potential applications, e.g. in biosensing, for which the activity may not only be preserved, but also enhanced if optimized conditions are identified. Optimization is not straightforward because several requirements must be fulfilled, including a suitable matrix and film-forming technique. In this study, we show that horseradish peroxidase (HRP) has its activity enhanced when immobilized in Langmuir-Blodgett (LB) films, in conjunction with dipalmitoylphosphatidylglycerol (DPPG). Incorporation of HRP into a DPPG monolayer at the air-water interface was demonstrated with compression isotherms, and Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS). From the PM-IRRAS data, we inferred that HRP was not denatured when adsorbed on a pre-formed, low pressure DPPG monolayer. A change in orientation was induced by the phospholipid matrix, with the amide C{double bond, short}O and NH groups from HRP being oriented perpendicular to the surface, parallel to the DPPG acyl chains, i.e. the α-helix was inserted into the monolayer. The mixed DPPG-HRP monolayer could be transferred onto solid supports, to which HRP activity was ca. 23% higher than in solution. The control of molecular architecture and choice of a suitable phospholipid matrix allowed HRP-containing LB films to be used in sensing peroxide.
KW - Air-water interface
KW - Cell membrane
KW - Enzyme activity
KW - Horseradish peroxidase
KW - Langmuir monolayer
KW - Langmuir-Blodgett film
UR - http://www.scopus.com/inward/record.url?scp=52149087451&partnerID=8YFLogxK
U2 - 10.1016/j.bbamem.2008.05.012
DO - 10.1016/j.bbamem.2008.05.012
M3 - Article
C2 - 18585999
AN - SCOPUS:52149087451
SN - 0005-2736
VL - 1778
SP - 2291
EP - 2297
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 10
ER -