Development of Gluten-Free Rice Flour Noodles That Suit the Tastes of Japanese People.

Gluten-free rice flour noodles with a flavor and texture profile preferred by the Japanese people were developed. The rice noodles contained potato starch (PS) as a binder. "Koshihikari" was selected from several candidate varieties based on its pasting properties. Since the Japanese people prefer the chewy texture of wheat flour "Udon" noodles, first, the stress-strain characteristics of "Udon" noodles in Japan were quantified, using a mechanical test. Next, different formulations of rice noodles were prepared by changing the amount of PS blended into the noodles. The mechanical tests on wheat and rice noodles show that rice noodles made from 85% rice flour and 15% PS have a texture similar to that of "Udon" noodles. Brown rice noodles containing roasted brown rice flour were also developed. Since brown rice flour hinders the binding of the dough, it was necessary to increase the amount of PS to increase the binding of roasted brown rice flour. Finally, noodles with 70% white rice flour, 10% brown rice flour, and 20% PS were produced. The gas chromatography-mass spectrometry analysis of the volatile compounds contained in white rice noodles and brown rice noodles identified the volatile compounds characteristic each of type.

Structure, design, and mechanics of a paper spring.

A paper spring is a simple paper craft popular with children. It can be constructed by interfolding and gluing two long strips of paper of equal sizes, with the simplest possible crease patterns. In addition to its curious springy response, this origami-based composite exhibits a twist deformation during its extension. Although its interlocking structure is expected to underly the strong stretch-twist coupling, a detailed understanding of it remains elusive. Here we quantify the kinematics and mechanics of a paper spring during its extensional actuation by combining experimental, numerical, and analytical approaches. We directly link the nonlinear mechanics of a paper spring with its structural design and the sheet elasticity. We show that the unique interlocking provides an enhanced structural rigidity because the thin sheets suffer from geometric frustrations and must locally bend and stretch during extension. This structural design allows for a reversible transformation between the rotatory and linear motions solely by controlling forces and moments applied at the ends of the structure. Such deployment kinematics could provide a unique avenue of the mode conversion for potential applications and will broaden the possibilities of future designs of origami-based springs with tunable functionalities.

Development of anti-HIV peptides based on a viral capsid protein.

Peptide inhibitors with cell permeability targeting an HIV-1 capsid (CA) protein might make therapeutic by regulating HIV-1 replication. Overlapping fragment peptide libraries covering the whole sequence of an HIV-1 CA protein have been synthesized with the addition of an octa-arginyl moiety to increase their cell permeability. Amongst these peptides, several compounds which inhibit the HIV-1 replication cycle have been found. Conjugation of cell-penetrating functions such as an octa-arginyl group to individual peptides in combination with the addition of chloroquine in cell-based anti-HIV assays was previously proven to be a useful assay method with which to search for active peptides. Anti-HIV assays have been performed in the presence or absence of chloroquine and found that most of compounds have higher anti-HIV activity in the presence, rather than in the absence of chloroquine. Some potent seeds as anti-HIV agents might naturally lie hidden in CA proteins, and could become useful leads to HIV inhibitors.

Electronic control of ligand-binding preference of a myoglobin mutant.

The L29F mutant of sperm whale myoglobin (Mb), where the leucine 29 residue was replaced by phenylalanine (Phe), was shown to exhibit remarkably high affinity to oxygen (O2), possibly due to stabilization of the heme Fe atom-bound O2 in the mutant protein through a proposed unique electrostatic interaction with the introduced Phe29, in addition to well-known hydrogen bonding with His64 [Carver, T. E.; Brantley, R. E.; Singleton, E. W.; Arduini, R. M.; Quillin, M. L.; Phillips, G. N., Jr.; Olson, J. S. J. Biol. Chem., 1992, 267, 14443-14450]. We analyzed the O2 and carbon monoxide (CO) binding properties of the L29F mutant protein reconstituted with chemically modified heme cofactors possessing a heme Fe atom with various electron densities, to determine the effect of a change in the electron density of the heme Fe atom (ρ(Fe)) on the O2 versus CO discrimination. The study demonstrated that the preferential binding of O2 over CO by the protein was achieved through increasing ρ(Fe), and the ordinary ligand-binding preference, that is, the preferential binding of CO over O2, by the protein was achieved through decreasing ρ(Fe). Thus, the O2 and CO binding preferences of the L29F mutant protein could be controlled through electronic modulation of intrinsic heme Fe reactivity through a change in ρ(Fe). The present study highlighted the significance of the tuning of the intrinsic heme Fe reactivity through the heme electronic structure in functional regulation of Mb.

Relationship between oxygen affinity and autoxidation of myoglobin.

Studies using myoglobins reconstituted with a variety of chemically modified heme cofactors revealed that the oxygen affinity and autoxidation reaction rate of the proteins are highly correlated to each other, both decreasing with decreasing the electron density of the heme iron atom. An Fe(3+)-O(2)(-)-like species has been expected for the Fe(2+)-O(2) bond in the protein, and the electron density of the heme iron atom influences the resonance process between the two forms. A shift of the resonance toward the Fe(2+)-O(2) form results in lowering of the O(2) affinity due to an increase in the O(2) dissociation rate. On the other hand, a shift of the resonance toward the Fe(3+)-O(2)(-)-like species results in acceleration of the autoxidation through increasing H(+) affinity of the bound ligand.