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SUMMARY A new structure and control method for a variable magnetic flux motor (VMFM) is proposed to achieve a high-efficiency electric vehicle (EV) motor drive under a wide range of conditions. A VFMF prototype that was designed by considering the loss was manufactured and evaluated in an experiment. The prototype demonstrated low iron loss and sufficient max torque. Thus, the prototype can provide a high-efficiency drive with low output, which is frequently the case for EVs. Map control enables a wide phase angle for the vector-control drive of the VMFM under a changing magnetic flux. Thus, the VMFM provides a high-efficiency drive under a wide range of conditions. [ABSTRACT FROM AUTHOR]

Although Cu bonding wire excels over Au bonding wire in some respects such as production costs, it has not been widely used because of its poor bondability at second bonds due to surface oxidation. We conceived an idea of electroplating oxidation-resistant metal on the Cu bonding wire to prevent the surface oxidation. The electroplating of Au, Ag, Pd, and Ni over Cu bonding wire all increased bond strengths as expected, but it caused problematic ball shapes except Pd-plated Cu bonding wire. The wire could produce the same ball shape as that of Au bonding wire. It was also proved to have excellent bondability sufficient to replace Au bonding wire. That is, it excelled in bond strengths, defective bonding ratio, and wideness of ‘Parameter Windows.’ It also showed the same stability as Au bonding wire in reliability tests, while bonds of Cu bonding wire were deteriorated in a few of the tests. In short, the Pd-plated Cu bonding wire can realize excellent bonding similar to Au bonding wire, while having much lower production costs. [ABSTRACT FROM AUTHOR]

N-Acetyl-γ-glutamyl-phosphate reductase (AGPR) catalyzes the third step in an eight-step arginine-biosynthetic pathway that starts with glutamate. This enzyme converts N-acetyl-γ-glutamyl phosphate to N-acetylglutamate-γ-semialdehyde by an NADPH-dependent reductive dephosphorylation. AGPR from Oryza sativa (OsAGPR) was expressed in Escherichia coli at 291 K as a soluble fusion protein with an upstream thioredoxin-hexahistidine [Trx-(His)6] extension. OsAGPR(Ala50–Pro366) was purified and crystals were obtained using the sitting-drop vapour-diffusion method at 293 K and diffract X-rays to at least 1.8 Å resolution. They belong to the hexagonal space group P61, with unit-cell parameters a = 86.11, c = 316.3 Å. [ABSTRACT FROM AUTHOR]

UDP- N-acetylglucosamine pyrophosphorylase (UAP) is an essential enzyme in the synthesis of UDP- N-acetylglucosamine. UAP from Candida albicans was purified and crystallized by the sitting-drop vapour-diffusion method. The crystals of the substrate and product complexes both diffract X-rays to beyond 2.3 Å resolution using synchrotron radiation. The crystals of the substrate complex belong to the triclinic space group P1, with unit-cell parameters a = 47.77, b = 62.89, c = 90.60 Å, α = 90.01, β = 97.72, γ = 92.88°, whereas those of the product complex belong to the orthorhombic space group P212121, with unit-cell parameters a = 61.95, b = 90.87, c = 94.88 Å. [ABSTRACT FROM AUTHOR]

N-acetylglucosamine-phosphate mutase (AGM1) is an essential enzyme in the synthesis of UDP- N-acetylglucosamine (UDP-GlcNAc) in eukaryotes and belongs to the α-d-phosphohexomutase superfamily. AGM1 from Candida albicans (CaAGM1) was purified and crystallized by the sitting-drop vapour-diffusion method. The crystals obtained belong to the primitive monoclinic space group P21, with unit-cell parameters a = 60.2, b = 130.2, c = 78.0 Å, β = 106.7°. The crystals diffract X-rays to beyond 1.8 Å resolution using synchrotron radiation. [ABSTRACT FROM AUTHOR]

A novel alkaline serine protease (KP-43) which belongs to a new class of the subtilisin superfamily was crystallized by the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. The crystals belong to the orthorhombic space group C2221, with unit-cell parameters a = 43.50 (2), b = 110.4 (1), c 168.9 (1) Å. The crystals diffract X-rays beyond 1.9 Å resolution using Cu Kα radiation from a rotating-anode generator and are suitable for high-resolution crystal structure analysis. [ABSTRACT FROM AUTHOR]

N-acetylglucosamine-phosphate mutase (AGM1) is an essential enzyme in the synthetic process of UDP-N-acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is a UDP sugar that serves as a biosynthetic precursor of glycoproteins, mucopolysaccharides, and the cell wall of bacteria. Thus, a specific inhibitor of AGM1 from pathogenetic fungi could be a new candidate for an antifungal reagent that inhibits cell wall synthesis. AGM1 catalyzes the conversion of N-acetylglucosamine 6-phosphate (GlcNAc-6-P) into N-acetylglucosamine 1-phosphate (GlcNAc-1-P). This enzyme is a member of the alpha-D-phosphohexomutase superfamily, which catalyzes the intramolecular phosphoryl transfer of sugar substrates. Here we report the crystal structures of AGM1 from Candida albicans for the first time, both in the apoform and in the complex forms with the substrate and the product, and discuss its catalytic mechanism. The structure of AGM1 consists of four domains, of which three domains have essentially the same fold. The overall structure is similar to those of phosphohexomutases; however, there are two additional beta-strands in domain 4, and a circular permutation occurs in domain 1. The catalytic cleft is formed by four loops from each domain. The N-acetyl group of the substrate is recognized by Val-370 and Asn-389 in domain 3, from which the substrate specificity arises. By comparing the substrate and product complexes, it is suggested that the substrate rotates about 180 degrees on the axis linking C-4 and the midpoint of the C-5-O-5 bond in the reaction.

The crystal structure of an oxidatively stable subtilisin-like alkaline serine protease, KP-43 from Bacillus sp. KSM-KP43, with a C-terminal extension domain, was determined by the multiple isomorphous replacements method with anomalous scattering. The native form was refined to a crystallographic R factor of 0.134 (Rfree of 0.169) at 1.30-A resolution. KP-43 consists of two domains, a subtilisin-like alpha/beta domain and a C-terminal jelly roll beta-barrel domain. The topological architecture of the molecule is similar to that of kexin and furin, which belong to the subtilisin-like proprotein convertases, whereas the amino acid sequence and the binding orientation of the C-terminal beta-barrel domain both differ in each case. Since the C-terminal domains of subtilisin-like proprotein convertases are essential for folding themselves, the domain of KP-43 is also thought to play such a role. KP-43 is known to be an oxidation-resistant protease among the general subtilisin-like proteases. To investigate how KP-43 resists oxidizing reagents, the structure of oxidized KP-43 was also determined and refined to a crystallographic R factor of 0.142 (Rfree of 0.212) at 1.73-A resolution. The structure analysis revealed that Met-256, adjacent to catalytic Ser-255, was oxidized similarly to an equivalent residue in subtilisin BPN'. Although KP-43, as well as proteinase K and subtilisin Carlsberg, lose their hydrolyzing activity against synthetic peptides after oxidation treatment, all of them retain 70-80% activity against proteinaceous substrates. These results, as well as the beta-casein digestion pattern analysis, have indicated that the oxidation of the methionine adjacent to the catalytic serine is not a dominant modification but might alter the substrate specificities.

The crystal structure of a calcium-free alpha-amylase (AmyK38) from Bacillus sp. strain KSM-K38, which resists chelating reagents and chemical oxidants, has been determined by the molecular replacement method and refined to a crystallographic R-factor of 19.9% (R-free of 23.2%) at 2.13-A resolution. The main chain folding of AmyK38 is almost homologous to that of Bacillus licheniformis alpha-amylase. However, neither a highly conserved calcium ion, which is located at the interface between domains A and B, nor any other calcium ions appear to exist in the AmyK38 molecule, although three sodium ions were found, one of which is located at the position corresponding to that of a highly conserved calcium ion of other alpha-amylases. The existence of these sodium ions was crystallographically confirmed by the structures of three metal-exchanged and mutated enzymes. This is the first case in which the structure of the calcium-free alpha-amylase has been determined by crystallography, and it was suggested that these sodium ions, instead of calcium ions, are used to retain the structure and function of AmyK38.