Two regions of the Mn-stabilizing protein from Synechococcus elongatus that are involved in binding to photosystem II complexes

Limited proteolysis of the Mn-stabilizing protein (MSP) from the thermophilic cyanobacterium Synechococcus elongatus with chymotrypsin, trypsin or lysylendopeptidase that yielded four major polypeptides of 26 kDa, 22 kDa, 15 kDa and 11 kDa on denaturing gel electrophoresis resulted in total loss of the binding capacity of the protein to PSII complexes. Analyses of electrophoretic patterns and amino-terminal sequences of the proteolytic products revealed that the three proteases specifically cleaved the protein at a site between Phe156 and Gly163 or between Arg184 and Ser191. Site-directed mutagenesis was used to construct two mutant MSPs that had a nick between Phe156 and Leu157, a chymotrypsin-cleavage site, and Met before Leu157 or in place of Leu157. The two mutant proteins failed to bind to PSII complexes, although they largely retained ordered secondary structure and comigrated with the wild-type proteins in non-denaturing gel electrophoresis. The loss of the protein binding can be ascribed to introduction of a nick because a mutant protein that had Met in place of Leu157 but no nick was able to specifically bind to the functional site of PSII complexes and restore the oxygen-evolving activity as effectively as the wild-type protein. In contrast, a mutant MSP with Met inserted between Phe156 and Leu157 bound only weakly and non-specifically to PSII complexes and failed to reactivate oxygen evolution. Thus, the binding of the protein to the functional site of the PSII complex was highly sensitive to a small structural change that was caused by cleavage or insertion of a single amino acid residue between Phe156 and Leu157. The results suggest that the Phe156-Gly163 and Arg184-Ser191 sequences of the cyanobacterial MSP are regions for interaction with PSII complexes.     

Evaluation of the Parallel Conductor Theory for Measuring Human Limb Blood Flow by Electrical Admittance Plethysmography

We devised a compensation technique that measures the admittance change of a limb submerged in an electrolyte solution in a cylinder. Using this technique, we evaluated the accuracy of admittance plethysmography and the validity of the parallel-conductor model on which the theory of blood flow measurement by electrical admittance (or impedance) plethysmography is based. From a theoretical point of view, if a limb is regarded as a parallel-conductor model, the admittance change due to blood pooling following venous occlusion should disappear when the resistivity of the solution is equal to that of the blood.     

Statistical analysis of 1186 cases of gastric carcinoma: with special reference to advanced lesion (author's transl)

750 cases of advanced gastric carcinoma were macroscopically and microscopically studied in relation with the 10 year survival rate. Most of the patients, 59.3% in female and 68.8% in male, belonged to the 5th and 6th decades. Macroscopically 44.1% of the cases were grouped in Borrmann III type, and secondly Early-Cancer Like Lesion, 26,6%. Histologically, in 510 cases out of 750 (68.0%) serosa was definitely broken by carcinoma cell nests and in 500 cases (66.7%) lymphnode metastasis was observed. The most frequent histological type was diffuse type, 44.9%, and secondly papillotubular type, 21.2%. 10 year survival rate of 516 cases, in which no residual cancer tissue was ascertained and the favorite prognosis could be expected was studied on various factors: Early-Cancer-Like-Lesion and Borrmann I & II types carcinoma, those cases in which the muscularis propria or serosa was preserved, those cases without lymphnode metastasis, and papillotubular or medullary tubular carcinomas showed a favorite prognosis in comparison with other types.     

XAFS Analysis for Niobium Carbide Particle Growth on Silica Support During Preparation Process

SiO₂-supported NbC catalysts were prepared by using temperature-programmed reactions (TPR). XAFS analysis confirmed that Nb₂O₅ was reduced to NbO₂ in the first TPR stage and converted into NbC in the second TPR stage. Nb particles grew only in the second TPR stage. Formation of highly dispersed NbC particles on SiO₂ surfaces was achieved.     

Characterization of methyl‐substituted polyamides used for reverse osmosis membranes by positron annihilation lifetime spectroscopy and MD simulation

Three kinds of polyamides were synthesized from three diamines and 1,3,5‐benzenetricarbonyl trichloride (TMC). The diamines used were m‐phenylene diamine, N‐methyl‐m‐phenylenediamine, and N,N′‐dimethyl‐m‐phenylenediamine. The average free volume sizes of the polyamides were measured by positron annihilation lifetime spectroscopy (PALS), and the free volume fractions were evaluated by molecular dynamics (MD) simulations. The methyl substitution on amino groups of diamines brought about an increase in interstitial space of molecular chains of the polyamides. In addition, reverse osmosis (RO) membranes were prepared by interfacial polymerization from the three diamines and TMC. The increase in the degree of methyl‐substitution of diamines led to increased chlorine resistance and decreased salt rejections of the polyamide RO membranes. Thus, the methyl‐substitution of diamines significantly influenced membrane performance. The vacancy sizes and fractional volumes in polyamides evaluated by PALS measurement and MD simulation were well correlated with salt rejection of polyamide RO membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

X‐Ray reflectivity study of polyimide thin films swollen by 1,3‐butadiene and n‐butane

X‐ray reflectivity measurements were performed on two different polyimide thin films synthesized from 2,2‐bis(3,4‐carboxyphenyl)hexafluoropropane dianhydride (6FDA) in 1,3‐butadiene and n‐butane. In 1,3‐butadiene at 2.3 atm, the film thickness increased by 24–30%. However, the film thickness increased by only 10% in n‐butane at 2.3 atm. Excessive increases in film thickness were shown in 1,3‐butadiene, but the decreases in film density were minor. The probability of the condensation of 1,3‐butadiene in the films is indicated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1818–1825, 2000