Microindentation Hardness of Protein Crystals under Controlled Relative Humidity

Kishi, Takeharu; Suzuki, Ryo; Shigemoto, Chika; Murata, Hidenobu; Kojima, K.; Tachibana, Masaru

doi:10.3390/cryst7110339

Cited by 10 publications

(8 citation statements)

References 49 publications

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“…Furthermore, brittle material characteristics were observed for all of the crystals in the presence of all impurities. Kishi et al [10] studied the indentation hardness on the (110) habit plane of hen-egg white lysozyme crystals with intracrystalline water with various levels of relative humidity. A strong correlation was found between crystal hardness and water content in the crystals, which was related to the evaporation and humidity.…”

Section: Introductionmentioning

confidence: 99%

Effects of polyelectrolytes on the hardness of borax decahydrate crystals

Polat¹,

Sayan²

2019

Journal of Boron

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The hardness of borax decahydrate crystals was measured using cationic polyelectrolytes of FO4115, FO4400 and FO4990 with anionic polyelectrolytes of AN923, AN930 and AN999 as an additive. The measurements were carried out in the indentation load range of 10 g to 30 g. It was determined that the Vickers hardness (H V) decreased with increasing applied load, showing that the borax decahydrate crystals exhibited an indentation size effect. Vickers microhardness measurements revealed that pure borax decahydrate crystals had a brittle structure, yet the crystals obtained in additive media were categorized as a soft material. The proportional specimen resistance model was applied to determine the load-independent microhardness. The crystal hardness of borax decahydrate was found to change depending on the type and concentration of polyelectrolyte used. In addition to the mechanical properties, the thermal and physical characteristics of borax decahydrate crystals were investigated by thermogravimetric and Fourier transform infrared spectroscopy analysis. The characterization results confirmed that the polyelectrolytes were adsorbed on the crystal's surface.

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Section: Introductionmentioning

confidence: 99%

Effects of polyelectrolytes on the hardness of borax decahydrate crystals

Polat¹,

Sayan²

2019

Journal of Boron

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“…These results can be explained by the fact that the anisotropic properties correlate with the crystal packing. Previous studies reported the dependence of hardness on the indented crystal plane [13,15,17,43,57]. These past studies showed a relationship between plastic deformation, dislocation multiplication, and motion in inducing a slip.…”

Section: Anisotropic Behavior Of Native Hheg Crystalsmentioning

confidence: 98%

“…Since the mechanical stability of particulate biocatalysts is a fundamental property required for industrial applications, knowledge of the mechanical properties of these biocatalysts is of great interest. Previous studies have reported on the micromechanics of native protein crystals [12][13][14][15][16][17], as well as their fragility and sensitivity to environmental changes [18,19]. In recent years, there has been increasing interest in enhancing mechanical stability by cross-linking enzyme crystals [20,21].…”

Section: Introductionmentioning

confidence: 99%

The Depth-Dependent Mechanical Behavior of Anisotropic Native and Cross-Linked HheG Enzyme Crystals

et al. 2021

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Enzymes are able to catalyze various specific reactions under mild conditions and can, therefore, be applied in industrial processes. To ensure process profitability, the enzymes must be reusable while ensuring their enzymatic activity. To improve the processability and immobilization of the biocatalyst, the enzymes can be, e.g., crystallized, and the resulting crystals can be cross-linked. These mechanically stable and catalytically active particles are called CLECs (cross-linked enzyme crystals). In this study, the influence of cross-linking on the mechanical and catalytic properties of the halohydrin dehalogenase (HheG) crystals was investigated using the nanoindentation technique. Considering the viscoelastic behavior of protein crystals, a mechanical investigation was performed at different indentation rates. In addition to the hardness, for the first time, depth-dependent fractions of elastic and plastic deformation energies were determined for enzyme crystals. The results showed that the hardness of HheG enzyme crystals are indentation-rate-insensitive and decrease with increases in penetration depth. Our investigation of the fraction of plastic deformation energy indicated anisotropic crystal behavior and higher irreversible deformation for prismatic crystal faces. Due to cross-linking, the fraction of elastic energy of anisotropic crystal faces increased from 8% for basal faces to 68% for prismatic crystal faces. This study demonstrates that mechanically enhanced CLECs have good catalytic activity and are, therefore, suitable for industrial use.

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“…These properties make protein crystals unique. , In addition, their porous region contains a large amount of intracrystalline water (30–70 vol %) . The mechanical properties of protein crystals, such as hardness and elastic constants, depend on the content of the intracrystalline water. − Moreover, it has recently been demonstrated that protein crystals such as glucose isomerase and ferritin have perfect crystallinity, such as dislocation-free crystals, similar to those of Si, Ge, and diamond. , Such attractive features may help advance the field of material science. ,, …”

Section: Introductionmentioning

confidence: 99%

Diffusion Coefficient of Intracrystalline Water in Intrinsic Hen Egg-White Lysozyme Crystals Determined by Confocal Raman Spectroscopy

et al. 2022

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Protein crystals composed of protein molecules are expected as a novel porous material. They have high porosity, and the knowledge of the diffusion of intracrystalline water is important. In this study, the diffusion coefficient of intracrystalline water in intrinsic hen egg-white lysozyme (HEWL) crystals was determined by a method that combines confocal Raman spectroscopy and air convection with controlled relative humidity. Similar to common porous materials, the drying process of the protein crystals includes three periods: constant-rate drying, falling-rate drying, and equilibrium state. During the falling-rate drying period, the drying rate depends on the diffusion of intracrystalline water in the protein crystal. The gradient of the water content was measured using confocal Raman spectroscopy. The diffusion coefficient of the intrinsic HEWL crystals was determined as 3.1 × 10 −7 cm 2 /s with a water content of 36.3 vol %. The estimated diffusion coefficients of the intrinsic HEWL crystals without cross-linking were in close agreement with those of the cross-linked protein crystals. This study is timely as the knowledge of the intrinsic diffusion coefficient is useful not only for understanding the mechanism of hydration of proteins but also in practical applications such as porous materials, drug binding, and cryoprotectant soaks.

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Microindentation Hardness of Protein Crystals under Controlled Relative Humidity

Cited by 10 publications

References 49 publications

Effects of polyelectrolytes on the hardness of borax decahydrate crystals

Effects of polyelectrolytes on the hardness of borax decahydrate crystals

The Depth-Dependent Mechanical Behavior of Anisotropic Native and Cross-Linked HheG Enzyme Crystals

Diffusion Coefficient of Intracrystalline Water in Intrinsic Hen Egg-White Lysozyme Crystals Determined by Confocal Raman Spectroscopy

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