Cavity resonator for circularly polarized microwave irradiation mounted on a cryostat

We have constructed a cylindrical cavity resonator with a hybrid coupler where circularly polarized microwaves can be irradiated to a sample. The polarity of the microwave can be switched by changing the input ports of the hybrid coupler. The cavity resonator is small enough to be mounted on a cryostat which enables us to change the sample temperature in a wide range. To demonstrate the performance of the cavity resonator mounted on a cryostat, Yttrium Iron Garnet (YIG) was used as a test sample. We succeeded in selectively exciting left and right circularly polarized modes with high polarization (>80%). We also evaluated the susceptibility tensor of YIG in the cryostat. The technique presented here would offer a new direction in the fields of spintronics and quantum information.

Protein aggregation suppressor arginine as an effective mouth cleaning agent

We have tested here whether or not arginine, a well-known aggregation suppressor, is effective in removing bacterial cells, which may present a potential risk of accidental pneumonia infection in aged individuals, from the oral mucosal membranes. This is based on the ability of arginine to suppress protein-protein interaction and surface adsorption and increase the solubility of organic compounds. Twelve student volunteers were subjected to mouthwashes with saline, citrate buffer (pH 3.5), arginine (pH 3.5) and a commercial Listerine. Insignificant effects were observed with saline and citrate buffer, whereas arginine and Listerine mouthwashes led to significant reduction of bacterial cells from the dorsal side of the volunteer's tongue. Arginine also appeared to disrupt biofilms present in the mouth.

Insoluble expression of highly soluble halophilic metal binding protein for metal ion biosorption: Application of aggregation-prone peptide from hen egg white lysozyme

Insoluble expression of intrinsically soluble proteins with native activity is potentially a promising alternative to soluble expression of folded protein or insoluble expression of unfolded protein requiring refolding. Here, we attempted to express highly soluble halophilic His-rich metal binding protein (HP) as insoluble inclusion bodies with native metal-binding activity using insolubilizing nona-peptide (Ins), GILQINSRW, derived from hen egg white lysozyme (His-InsHP). About 80% of expressed His-InsHP was localized in inclusion bodies in Na-phosphate/NaCl buffer, pH 7.4, while His-HP without Ins peptide was exclusively expressed in soluble supernatant. We report expression, purification and characterization of this insoluble His-InsHP, and its possible application for efficient biosorption and recovery of environmental metal ions, for example, by using whole bacterial cells expressing insoluble His-InsHP as a new cost-effective metal ion-adsorbent.

Protein Solvent Interaction: Transition of Protein-solvent Interaction Concept from Basic Research into Solvent Manipulation of Chromatography

Previously, we have reviewed in this journal (Arakawa, T., Kita, Y., Curr. Protein Pept. Sci., 15, 608-620, 2014) the interaction of arginine with proteins and various applications of this solvent additive in the area of protein formulations and downstream processes. In this special issue, we expand the concept of protein-solvent interaction into the analysis of the effects of solvent additives on various column chromatography, including mixed-mode chromatography. Earlier in our research, we have studied the interactions of such a variety of solvent additives as sugars, salts, amino acids, polymers and organic solvents with a variety of proteins, which resulted in mechanistic understanding on their protein stabilization and precipitation effects, the latter known as Hofmeister series. While such a study was then a pure academic research, rapid development of genetic engineering technologies and resultant biotechnologies made it a valuable knowledge in fully utilizing solvent additives in manipulation of protein solution, including column chromatography.

Rikkunshito simultaneously improves dyspepsia correlated with anxiety in patients with functional dyspepsia: A randomized clinical trial (the DREAM study)

BACKGROUND

Functional dyspepsia (FD), a heterogeneous disorder, involves multiple pathogenetic mechanisms. Developing treatments for FD has been challenging. We performed a randomized, placebo-controlled, double-blind clinical trial to determine the efficacy of rikkunshito, a Japanese herbal medicine, in FD patients.

METHODS

FD patients (n = 192) who met the Rome III criteria without Helicobacter pylori infection, predominant heartburn, and depression were enrolled at 56 hospitals in Japan. After 2 weeks of single-blind placebo treatment, 128 patients with continuous symptoms were randomly assigned to 8 weeks of rikkunshito (n = 64) or placebo (n = 61). The primary efficacy endpoint was global assessment of overall treatment efficacy (OTE). The secondary efficacy endpoints were improvements in upper gastrointestinal symptoms evaluated by the Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM), the Global Overall Symptom scale (GOS), and the modified Frequency Scale for the Symptoms of Gastroesophageal Reflux Disease (m-FSSG), and psychological symptoms evaluated by the Hospital Anxiety and Depression Scale (HADS).

KEY RESULTS

Rikkunshito increased OTE compared to placebo at 8 weeks (P = .019). Rikkunshito improved upper gastrointestinal symptoms (PAGI-SYM, GOS, and m-FSSG) at 8 weeks, especially postprandial fullness/early satiety (P = .015 and P = .001) and bloating (P = .007 and P = .002) of the PAGI-SYM subscales at 4 weeks and 8 weeks. Improvement of HADS at 8 weeks (P = .027) correlated with those of PAGI-SYM (r = .302, P = .001), GOS (r = .186, P = .044), and m-FSSG (r = .462, P < .001), postprandial fullness/early satiety (r = .226, P = .014), dyspepsia (r = .215, P = .019), and PDS (r = .221, P = .016).

CONCLUSION & INFERENCES

Rikkunshito may be beneficial for FD patients to simultaneously treat gastrointestinal and psychological symptoms.

Generation of a recombinant Aggregatibacter actinomycetemcomitans RTX toxin in Escherichia coli

A leukotoxin (LtxA) that is produced by Aggregatibacter actinomycetemcomitans (Aa) is an important virulence determinant in an aggressive form of periodontitis in adolescents. Understanding the function of this protein at the molecular level is critical to elucidating its role in the disease process. To accomplish genetic analysis of the protein structure and relating these observations to toxin function, we have developed an E. coli expression system for the generation and rapid purification of LtxA. Cloning the structural toxin gene, ltxA, from Aa strain JP2 under control of T7 promoter-1 of pCDFDuet-1 vector resulted in expression of a 114 KDa protein which could be easily purified by the presence of a carboxy-terminal engineered double hexahistidine (double-His₆) tag and was immunologically reactive with an anti-LtxA monoclonal antibody, but was not cytotoxic. Cloning a second gene, ltxC, an acyltransferase gene, into the vector under control of T7 promoter-2, resulted in expression of the biologically active LtxA. The toxin was extracted from E. coli inclusion bodies, purified by immobilized metal affinity chromatography, and refolded by dialysis. When compared by circular dichroism (CD) spectroscopy analysis, acylated recombinant LtxA has a secondary structure consistent with wt LtxA, while variations in α-helical structure of nonacylated LtxA were observed. No modifications in α-helix were found upon the toxin's binding with liposome-incorporated cholesterol. Our results suggest that pure, biologically active recombinant LtxA can be isolated by a one-step affinity chromatography from E. coli. The toxic and structural properties of the recombinant LtxA are similar to its wt counterpart.

Allantoin and hydantoin as new protein aggregation suppressors

Allantoin is widely used in pharmaceutical and cosmetic products, and is composed of a hydantoin ring and a ureido group. Recent reports showed that allantoin suppresses thermal aggregation of hen egg white lysozyme (LYZ). However, structural insight into the properties of allantoin on protein aggregation and whether allantoin controls the aggregation of other proteins under different stress conditions remain unclear. Here we studied the structural properties of allantoin in terms of its effects on protein aggregation by comparing allantoin with urea and hydantoin. Furthermore, we analyzed the effects of allantoin and its derivatives on the aggregation of LYZ, carbonic anhydrase from bovine erythrocytes (BCA), albumin from chicken egg white (OVA), and immunoglobulin G (IgG) by various stresses in comparison with arginine. These four proteins are widely different in charged state and molecular size. Allantoin suppressed the aggregation and inactivation of LYZ comparing to arginine without affecting the melting temperature of proteins, and was responsible for the slightly improved formation of soluble oligomers and insoluble aggregates of IgG with thermal and acidic stresses. In contrast, hydantoin increased the solubility of aromatic amino acids more effectively than arginine and allantoin. The structural properties underlying the observed effects of allantoin as an aggregation suppressor include hydrophobic interactions between hydantoin moiety and aromatic ring on the surface of proteins, which is reflected on the difference between allantoin and arginine. These results show that the backbone of hydantoin ring may be a new category of additives for development of small aggregation suppressors.

Protein-solvent interaction

Protein folding and assembly can be manipulated in in vitro systems by co-solvents at high concentrations. A number of co-solvents that enhance protein stability and assembly have been shown to be excluded from the protein surface. Such co-solvent exclusion has been demonstrated by dialysis experiments and shown to be correlated with their effects on protein stability and assembly.

Two Elution Mechanisms of MEP Chromatography

MEP (mercapto-ethyl-pyridine) HyperCel is one of the hydrophobic charge induction chromatography (HCIC) resins. Under normal operation, proteins are bound to the MEP resin at neutral pH, at which MEP is not charged, mostly via hydrophobic interaction. MEP has a pyridine group, whose pK is 4.8, and hence is positively charged at acidic pH range. Based on the binding mechanism (i.e., hydrophobic interaction) and the induced positive charge at acidic pH, there may be two ways to elute the bound proteins. One way is to bring the pH down to protonate both MEP resin and the bound protein, leading to charge repulsion and thereby elution. Another way is to use hydrophobic interaction modifiers, which are often used in hydrophobic interaction chromatography, to reduce hydrophobic interaction. Here, we summarize such two possible elution approaches.

Isoform Separation by a Mixed-mode Resin, TOYOPEARL MX-Trp-650M

TOYOPEARL particles are cross-linked hydroxylated methacrylic polymers available in different pore and particle sizes. They are conjugated with different ligands to generate ion-exchange, hydrophobic interaction and affinity resins. They have excellent physical and chemical properties. A mixed-mode resin, TOYOPEARL MX-Trp-650M, is made of this particle with tryptophan conjugated via N-terminal amino group and hence has both hydrophobic/aromatic side chain and carboxyl group. In this review, I will summarize the properties of the TOYOPEARL particles and MX-Trp-650M resin and application of this resin for purification of proteins and in some detail the separation of disulfide (SS)- scrambled oligomers of insulin-like growth factor-1 (IGF-1). For this particular application, the intact IGF-1 was used to examine binding and elution conditions of TOYOSCREEN MX-Trp-650M column. Strong binding was obtained at pH 4.0, at which arginine, but not NaCl, resulted in elution. Both NaCl and arginine resulted in elution at pH 6.5. In addition, a pH gradient from 4.0 to 8.5 was effective. When applied to SS-scrambled IGF-1 oligomers, both pH and arginine gradient exhibited an efficient separation of the oligomers.