A ligand field analysis of the spectroscopic differences between rubredoxin and desulforedoxin in the reduced state

We propose a ligand field model to interpret the differences between the spectroscopic properties of reduced rubredoxin and desulforedoxin. The experimental data are well reproduced by using a common set of ligand field parameters and slightly different values of the mixing parameter theta for the two proteins. In this class of iron-sulfur clusters, the rhombic distortion could be modulated by variations of the S-Fe-S angles.     

Spectroscopic studies of the oxidation-reduction properties of three forms of ferredoxin from Desulphovibrio gigas.

Electron paramagnetic resonance spectra were recorded of three forms of Desulphovibrio gigas ferredoxin, FdI, FdI' and FdII. The g = 1.94 signal seen in dithionite-reduced samples is strong in FdI, weaker in FdI' and very small in FdII. The g = 2.02 signal in the oxidized proteins is weak in FdI and strongest in FdII. It is concluded that most of the 4Fe-4S centres in FdI change between states C- and C2-; FdI' contain both types of centre. There is no evidence that any particular centre can change reversibly between all three oxidation states. Circular dichroism spectra show differences between FdI and FdII even in the diamagnetic C2- state. The redox potentials of the iron-sulphur centres of the three oligomers (forms) are different. After formation of the apo-protein of FdII and reconstitution with iron and sulphide, the protein behaves more like FdI, showing a strong g = 1.94 signal in the reduced states.     

Immobilized formaldehyde-metabolizing enzymes from Hansenula polymorpha for removal and control of airborne formaldehyde

Formaldehyde (FA)-containing indoor air has a negative effect on human health and should be removed by intensive ventilation or by catalytic conversion to non-toxic products. FA can be oxidized by alcohol oxidase (AOX) taking part in methanol metabolism of methylotrophic yeasts. In the present work, AOX isolated from a Hansenula polymorpha C-105 mutant (gcr1 catX) overproducing this enzyme in glucose medium, was tested for its ability to oxidize airborne FA. A continuous fluidized bed bioreactor (FBBR) was designed to enable an effective bioconversion of airborne FA by AOX or by permeabilized mutant H. polymorpha C-105 cells immobilized in calcium alginate beads. The immobilized AOX having a specific activity of 6-8 U mg?1 protein was shown to preserve 85-90% of the initial activity. The catalytic parameters of the immobilized enzyme were practically the same as for the free enzyme (k(cat)/K(m) was 2.35×103 M?1 s?1 vs 2.89×103 M?1 s?1, respectively). The results showed that upon bubbling of air containing from 0.3 up to 18.5 ppm FA through immobilized AOX in the range of 1.3-26.6 U g?1 of the gel resulted in essential decrease of FA concentration in the outlet gas phase (less than 0.02-0.03 ppm, i.e. 10-fold less than the threshold limit value). It was also demonstrated that a FBBR with immobilized permeabilized C-105 cells provided more than 90% elimination of airborne FA. The process was monitored by a specially constructed enzymatic amperometric biosensor based on FA oxidation by NAD+ and glutathione-dependent formaldehyde dehydrogenase from the recombinant H. polymorpha Tf 11-6 strain.     

Effects of exercise training modality on skeletal muscle fatigue in men with coronary heart disease

Cardiopulmonary and skeletal muscle effects of combined aerobic and resistance training vs. aerobic training were studied in men with coronary heart disease. Sixteen men with coronary heart disease underwent a cardiopulmonary exercise testing and a quadriceps skeletal muscle fatigue assessment. Patients were divided into two groups and trained in a combined aerobic and resistance or aerobic training group during 7 weeks. Maximal voluntary contraction and isometric endurance time were measured with electromyographic signals recorded from vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM) during isometric endurance time. Exercise tolerance increased only in the combined group (p < 0.05). Maximal voluntary contraction and isometric endurance time did not change after training in either group but was performed at 5.8% higher force output for the combined group. After training, median frequency values were higher for the VL and VM (p < 0.001) in the aerobic group and also higher for the VL, RF (p < 0.001) and VM (p < 0.05) in the combined group. Combined aerobic and resistance training was more effective to improve exercise tolerance, decrease skeletal muscle fatigue and correct neuromuscular alterations in men with coronary heart disease.     

Overexpression of ftsA induces large bulges at the septal regions inEscherichia coli

High-level expression offtsA, an essential cell division gene inEscherichia coli, inhibits cell septation and causes the formation of filaments that develop spherical bulges up to 4 m in diameter. These bulges may emanate from septation sites, since they were evenly spaced in relation to one another and to the cell poles. Electron microscopic examination of thin sections through the bulged regions reveals large electron-lucent, plate-like regions that appear to originate from the membrane. In addition, these bulging filamentous cells contain more hexosamine per mass than control cells. A model is proposed that the electron-lucent regions observed by electron microscopy are caused by peptidoglycan accumulation stimulated by the overexpression offtsA.     

Interstitial fluid, plasma protein, colloid, and leukocyte uptake into initial lymphatics

Ikomi, Fumitaka, James Hunt, Gayda Hanna, and Geert W. Schmid-Schönbein. Interstitial fluid, plasma protein,colloid, and leukocyte uptake into initial lymphatics.J. Appl. Physiol. 81(5):2060-2067, 1996.Lymphatics serve to remove from the interstitium a range of materials, including plasma proteins, colloid materials, andcells. Lymph flow rates can be enhanced by periodic tissue compressionor venous pressure elevation, but little is known to what degreeenhancement of lymph flow affects material transport. The objective wasto examine the uptake of plasma proteins, a colloidal perflubronemulsion (LA-11063, mean particle diameter = 0.34 µm), and leukocytesinto lymphatics. Prenodal collecting lymphatics in the lower hindlimbof rabbits were cannulated with and without foot massage and afterelevation of venous pressure (40 mmHg). The average lymph flow rateswere elevated ~22-fold by the skin massage but only about threefoldby venous pressure elevation. Lymph-to-plasma protein concentrationratio remained unchanged by the massage but decreased significantlyafter venous pressure elevation. Lymph colloid concentration andleukocyte counts were elevated on average 47 and 8.5 times,respectively, by foot massage, but both decreased after venous pressureelevation. These results suggest that skin movement by massage andelevation of the venous pressure lead to opposite lymph transportkinetics of protein, colloids, and cells. Massage is more effective to enhance material transport out of the interstitium into the initial lymphatics.

     

omp T: Escherichia coli K-12 structural gene for protein a (3b)

Chromosomal DNA from strain UT400, a previously described deletion mutant of Escherichia coli K-12 that lacks outer membrane protein a, failed to hybridize with plasmid DNA (pGGC110) containing the structural gene for protein a. We designate the genetic locus for protein a, located at approximately 12.5 min of the E. coli chromosome, ompT.     

Cloned DNA fragment specifying major outer membrane protein a in Escherichia coli K-12.

Plasmid pMC44 is a recombinant plasmid that contains a 2-megadalton EcoRI fragment of Escherichia coli K-12 DNA joined to the cloning vehicle, pSC101. The polypeptides specified by plasmid pMC44 were identified and compared with those specified by pSC101 to determine those that are unique to pMC44. Three polypeptides specified by plasmid pMC44 were localized in the cell envelope fraction of minicells: a Sarkosyl-insoluble outer membrane polypeptide (designated M2), specified by the cloned 2-megadalton DNA fragment, and two Sarkosyl-soluble membrane polypeptides specified by the cloning plasmid pSC101. Bacteria containing plasmid pMC44 synthesized quantities of M2 approximately equal to the most abundant E. coli K-12 outer membrane protein. Evidence is presented that outer membrane polypeptide M2, specified by the recombinant plasmid pMC44, is the normal E. coli outer membrane protein designated protein a by Lugtenberg and 3b by Schnaitman.