Molecular cloning, purification and characterization of two endo-1,4-beta-glucanases from Aspergillus oryzae KBN616

Two endo-1,4-beta-glucanase genes, designated celA and celB, from a shoyu koji mold Aspergillus oryzae KBN616, were cloned and characterized. The celA gene comprised 877 bp with two introns. The CelA protein consisted of 239 amino acids and was assigned to the cellulase family H. The celB gene comprised 1248 bp with no introns. The CelB protein consisted of 416 amino acids and was assigned to the cellulase family C. Both genes were overexpressed under the promoter of the A. oryzae taka-amylase A gene for purification and enzymatic characterization of CelA and CelB. CelA had a molecular mass of 31 kDa, a pH optimum of 5.0 and temperature optimum of 55 degrees C, whereas CelB had a molecular mass of 53 kDa, a pH optimum of 4.0 and temperature optimum of 45 degrees C.     

Probing the Superconducting Gap from Tunneling Conductance on NdFeAsO<Subscript>0.7</Subscript> with <Emphasis Type=Italic>T</Emphasis><Subscript>C</Subscript>=51 K

We report the tunneling spectroscopy of an iron-based oxypnictide NdFeAsO_0.7 with T _C=51 K, measured by a mechanical point contact technique. Mainly two kinds of tunneling spectra have been observed reproducibly. One is tunneling conductance displaying sharp superconducting gap peaks at 6.0±1.0 mV, in which hump (or kink) structures are also observed at 20–30 mV. Another is that showing dominantly the larger superconducting gap Δ _L with sharp conductance peaks at 14±1.0 meV, in which the trace of a smaller gap (Δ _S=5–7 meV) is simultaneously observed. Our results give direct evidence for the existence of multiple gaps in the quasiparticle excitation spectrum of this multiband system, although the origin of the hump at 20–30 mV is still unclear.     

Application of cryopreserved allograft to aortic root replacement for valve detachment case due to aortitis

A 54-year-old male who had received an aortic valve replacement with SJM 23 about 3 years before suffered from an acute cardiac failure because of the valve detachment. From his clinical course, it was diagnosed that the aortic valve insufficiency was complicated by an aortitis. We operated on him by an aortic root replacement using a cryopreserved allograft which we prepared. A donor of the allograft was 35-year-old male, died of a subarachnoidal hemorrhage. We harvested his aortic root at an autopsy and dipped it into a nutrition medium with 10% dimethylsulfoxide. Within 10 hours from his death, we froze the tissue using a program freezer and stored it in a liquid nitrogen for 7 months. After thawing it in 37 degrees C water quickly, we rinsed the graft and used for the operation. The cell viability of the graft was confirmed by a tissue culture. Indication of the allograft valve to an aortitis case is still controversial. We think the allograft is recommendable to valve detachment case due to aortitis, because the softness of the graft decreases a compliance mismatch between the graft and the patient's annulus, which may prevent redetachment. Although we felt concern about redetachment of the conduit due to the weakness of the patient's aortic annulus, no complication regarding the allograft happened at all as yet.     

Anisotropic Superconducting Properties of MgB2 and Related Compounds

Anisotropic superconducting properties of inter-metallic compounds MgB₂, Y₂PdGe₃, and CaAlSi with AlB₂ structure are studied by detailed angular dependent transport measurements. MgB₂ and CaAlSi shows appreciable anisotropy of the upper critical field, H _c2, with mass anisotropy parameter =3 and 2, respectively, while Y₂PdGe₃ is almost isotropic. In-plane anisotropy of H _c2 in these hexagonal superconductors is very small, consistent with the prediction based on GL theory.     

Synthesis of polypyridine-graft-PEG copolymer for protein repellent and stable interface

Polypyridine grafted with poly(ethylene glycol) (Py-g-PEG) have been synthesized. Radical copolymerization of methyl-terminated PEG macromonomer with 4-pyridylmethyl methacrylate homogeneously proceeded and the obtained copolymer spontaneously adsorbs from aqueous solution onto gold surfaces, where the pyridine parts act as the multipoint anchor to the surface and the PEG parts provide the strong steric repulsion between the chains. As a result, the highly protein repellent and stable surface was constructed through multipoint pyridine attachment as compared with singlepoint pyridine attachment. Py-g-PEGs thus synthesized are promising material to functionalize metal and semiconductor material and to self-assemble into micelle in biotechnological and biomedical field.