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Published on: August 7, 2014
Human serum albumin nanotubes with esterase activity
Teruyuki Komatsu1, Takaaki Sato, Christoph Boettcher
1Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan. komatsu@kc.chuo-u.ac.jp
Chemistry, an Asian Journal
|November 5, 2011
Summary
Layer-by-layer assembly created poly-L-arginine and human serum albumin nanotubes. These protein cylinders, approximately 100 nm thick, retained enzyme activity in hydrated conditions.
Area of Science:
- Biomaterials Science
- Nanotechnology
- Protein Engineering
Background:
- Layer-by-layer (LbL) assembly is a versatile technique for fabricating multilayered nanostructures.
- Human serum albumin (HSA) is a biocompatible protein with potential applications in drug delivery and tissue engineering.
- Poly-L-arginine (PLA) is a cationic polypeptide often used in LbL assembly due to its electrostatic interactions.
Purpose of the Study:
- To fabricate and characterize nanocylindrical wall structures using LbL assembly of PLA and HSA.
- To investigate the structural properties of these nanotubes in both lyophilized and hydrated states.
- To assess the retained biological activity of HSA when incorporated into the nanotube structure.
Main Methods:
- Layer-by-layer (LbL) assembly of poly-L-arginine (PLA) and human serum albumin (HSA).
- Characterization using scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo-TEM).
- Small-angle X-ray scattering (SAXS) for component size analysis and enzyme activity assays (para-nitrophenyl acetate hydrolysis).
Main Results:
- SEM and SFM revealed round, chimney-like architectures with ~100 nm wall thickness for lyophilized (PLA/HSA)(3) nanotubes.
- Cryo-TEM showed that hydrated tube walls consist of densely packed HSA molecules, indicating significant swelling in water.
- SAXS determined maximum diameters of ~28 nm for PLA and ~8 nm for HSA in solution, representing minimum layer thicknesses.
- HSA retained significant esterase activity within the nanotubes, with comparable Michaelis constant (K(m)) and catalytic constant (k(cat)) to free HSA.
Conclusions:
- LbL assembly successfully produced nanocylindrical structures from PLA and HSA.
- The protein nanotubes exhibit distinct structural characteristics in dry and hydrated states, with notable swelling.
- Incorporation into nanotubes preserves the functional enzymatic activity of HSA, suggesting potential for bioactive nanomaterial applications.
