We have gained evidence from our high-pressure NMR work on proteins that, unlike in crystals, proteins in solution fluctuate in general in a wide conformational space from within the basic folded (N) even to the fully unfolded (U). Increasing evidence indicates that high-energy sub-states, existing between the two, often have crucial roles in function. Here we find one such example in an enzyme T4 lysozyme, which hydrolyzes the glycosidic bond of the peptidoglycan hetero-polymer of the bacterial cell wall. In this article, we show how we analyze conformational fluctuations of T4 lysozyme in a wide conformational space with high-pressure NMR spectroscopic techniques, from which we identify the high-energy sub-states relevant to function.
Pressure perturbation calorimetry (PPC) is a relatively new calorimetric technique which allows us to investigate volume behavior of solute molecules in aqueous solutions or colloidal particles in aqueous dispersions. This article deals with the application of the PPC technique to phospholipid vesicle dispersions along with a brief description about the theoretical aspect of this technique on the basis of our recent studies on the volume and relaxation behavior of phospholipid bilayers.
Although the pressure effect on a canonical structure of duplex is very small, G-quadruplex DNA, which is one of the non-canonical structures, destabilized with increasing pressure as well as proteins. The volumetric parameters of the formation of G-quadruplex were largely affected by molecular environments such as molecular crowding conditions. The volumetric analysis of non-canonical structures by using high pressure opens a new category in nucleic acids chemistry, which helps us to understand the information of the bulk structure and hydration, and design new drugs for nucleic acids in a living cell.
Molecular motor is a typical molecular machinery in which the characteristic features of proteins are integrated; these include enzymatic activity, energy conversion, molecular recognition and self-assembly. These biologically important reactions occur with the association of water molecules that surround the motors. Applied pressures can alter the intermolecular interactions between the motors and water. Here, we describe the development of a high-pressure microscope and a new motility assay that enables the visualization of the motility of molecular motors under conditions of high pressure.
Shewanella species are mostly marine bacteria distributed widely from shallow- to deep-sea areas. The species from the deep-sea grow well under high pressure, exhibiting what is called ‘piezophilic growth’. In contrast, those from the shallow areas cannot grow under such high pressure, thus showing ‘piezo-sensitive growth’. Proteins from deep-sea piezophilic Shewanella must adapt to high pressure, which may otherwise affect protein structure. Proteins from both piezophilic and piezo-sensitive Shewanella species are useful tools for comparative analysis to understand the pressure adaptation mechanism of proteins. In this review, we presented some comparative studies on proteins from Shewanella and other related bacteria.
This paper describes the application of high-pressure treatment from a viewpoint of industrial utilization. High-pressure treatment induces the transformation of agricultural and livestock products, and this “pressure history” (the influence of high-pressure treatment) has an effect on later processes. A later enzymatic reaction is promoted by the destruction of the cell walls, even in post-harvest farm products. In addition, the heat-resistant spores decreased after receiving a high-pressure treatment of 200 MPa before heating sterilization, and even heating at 100℃ to 105℃ showed that food could still be sterilized.
The combination of high-resolution NMR spectroscopy with pressure perturbation, known as variable-pressure NMR spectroscopy or simply high-pressure NMR spectroscopy, is a relatively recent accomplishment, but is now a technique expanding rapidly with high promise in future. The importance of the method is that it allows, for the first time in history, a systematic detection and analysis of structures of high-energy sub-states in proteins along with their equilibrium populations. Here I describe how the method discloses the new concept and roles of proteins in the biological world. Furthermore, I expect that the knowledge on high-energy sub-states of proteins obtained in this way will contribute to a more logical and efficient use of pressure in food and other applications.
Knowledge about magma in the interior of the Earth is important to understand the formation and evolution of the early Earth, and the volcanic activity of current Earth. In order to replicate the Earth's internal conditions and study the deep magma, high-pressure techniques are necessary. In this article, high-pressure experiments on silicate melt/glass and newly acquired results are reviewed with focusing on the following 3 topics; (1) the gravitational stability and the mobility of magma in the Earth's and planetary interiors based on physical property (e.g., density and viscosity) measurements; (2) the effect of volatile components, such as H2O and CO2, on magma density; (3) the relationship between the degree of polymerization and the structure/properties of silicate melts and glasses under high-pressure condition.
Atomic diffusion rates and transformation mechanims of mantle minelars provide important constraints for understanding many physical and chemical processes in the Earth's interior, including mantle rheology and chemical transportation. Here I introduce two recent experimental studies on the atomic diffusivity and transformation mechanisms of mantle minerals under lower mantle conditions up to 50 GPa using a Kawai-type high-pressure apparatus combined with sintered diamond anvils. Diffusion-controlled growth kinetics of the polycrystalline MgSiO3 bridgmanite enabled us to estimate the grain boundary diffusivity of bridgmanite in the lower mantle. Also, metastability of the deep subducted plate was disscussed based on the mechanism changes through the post-garnet transformation under large over pressure conditions.