Human Serum Albumin Nanotubes with Esterase Activity

Abstract

A nanocylindrical wall structure was obtained by layer-by-layer (LbL) assembly of poly-L-arginine (PLA) and human serum albumin (HSA) and characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo-TEM). SEM and SFM measurements of a lyophilized powder of (PLA/HSA)(3) nanotubes yielded images of round, chimney-like architectures with approximately 100 nm wall thickness. Cryo-TEM images of the hydrated sample revealed that the tube walls are composed of densely packed HSA molecules. Moreover, when small-angle X-ray scattering was used to characterize the individual PLA and HSA components in aqueous solutions, maximum diameters of approximately 28 nm and 8 nm were obtained, respectively. These values indicate the minimum thickness of wall layers consisting of PLA and HSA. It can also be concluded from SEM as well as from cryo-TEM images that the protein cylinders are considerably swollen in the presence of water. Furthermore, HSA retains esterase activity if assembled in nanotubes, as indicated by measurements of para-nitrophenyl acetate hydrolysis under semi-physiological conditions (pH 7.4, 22 °C). The enzyme activity parameters (Michaelis constant, K(m), and catalytic constant, k(cat)) were comparable to those of free HSA.

Human serum albumin: From bench to bedside

“…Furthermore, the HSA nanotubes internally decorated with a-glucosidase catalyze the hydrolysis of 4-methyl-umbelliferyl-a-D-glucopyranoside to form a-D-glucose (Qu and Komatsu, 2010;Komatsu et al, 2011a,b). Very recently, HSA nanotubes with esterase activity have been produced; HSA retains its esterase activity and catalyzes p-nitrophenyl acetate hydrolysis (Komatsu et al, 2012). Lastly, recombinant HSA, which is currently manufactured on an industrial scale (Kobayashi, 2006), enables to develop the HSA nanotubes in practical use (Komatsu et al, 2011a).…”

Quantitative Collection and Enzymatic Activity of Glucose Oxidase Nanotubes Fabricated by Templated Layer-by-Layer Assembly

“…1 This inspired the synthesis of artificial nanostructures for performing reactions in confinement; different morphologies were developed, varying from spherical to tubular, such as nanoporous organic crystalline hosts, 2 micelles and vesicles, or nanocapsules 3-10 and nanotubes, [11][12][13][14][15] enabling confinement effects to be experimentally studied with these synthetic analogues.…”

Protein Needles as Molecular Templates for Artificial Metalloenzymes

“…[14][15][16][17] To introduce functions into these nanostructures various strategies have been developed, including (1) chemical modifications of metal complexes, [18][19][20][21] (2) design of peptides with high affinity to metal ions, [22][23][24][25][26] (3) fusion of foreign enzymes, [27][28][29][30] and (4) construction of artificial protein and peptide tubes. [31][32][33][34][35][36]…”

“…Komatsu and co-workers synthesized protein-based nanotubes to achieve catalytic reactions. [34][35][36] Nanotubes possessing α-Fe 2 O 3 nanoparticles were synthesized based on iron-storage protein, ferritin. [34] Layer-by-layer accumulation of poly-L-arginine (PLA) and ferritin into a track-etched polycarbonate membrane was performed to generate protein nanotubes.…”