Proton-NMR studies of the effects of ionic strength and pH on the hyperfine-shifted resonances and phenylalanine-82 environment of three species of mitochondrial ferricytochrome c.

Ferricytochromes c from three species (horse, tuna, yeast) display sensitivity to variations in solution ionic strength or pH that is manifested in significant changes in the proton NMR spectra of these proteins. Irradiation of the heme 3-CH3 resonances in the proton NMR spectra of tuna, horse and yeast iso-1 ferricytochromes c is shown to give NOE connectivities to the phenyl ring protons of Phe82 as well as to the beta-CH2 protons of this residue. This method was used to probe selectively the Phe82 spin systems of the three cytochromes c under a variety of solution conditions. This phenylalanine residue has previously been shown to be invariant in all mitochondrial cytochromes c, located near the exposed heme edge in proximity to the heme 3-CH3, and may function as a mediator in electron transfer reactions [Louie, G. V., Pielak, G. J., Smith, M. & Brayer, G. D. (1988) Biochemistry 27, 7870-7876]. Ferricytochromes c from all three species undergo a small but specific structural rearrangement in the environment around the heme 3-CH3 group upon changing the solution conditions from low to high ionic strength. This structural change involves a decrease in the distance between the Phe82 beta-CH2 group and the heme 3-CH3 substituent. In addition, studies of the effect of pH on the 1H-NMR spectrum of yeast iso-1 ferricytochrome c show that the heme 3-CH3 proton resonance exhibits a pH-dependent shift with an apparent pK in the range of 6.0-7.0. The chemical shift change of the yeast iso-1 ferricytochrome c heme 3-CH3 resonance is not accompanied by an increase in the linewidth as previously described for horse ferricytochrome c [Burns, P. D. & La Mar, G. N. (1981) J. Biol. Chem. 256, 4934-4939]. These spectral changes are interpreted as arising from an ionization of His33 near the C-terminus. In general, the larger spectral changes observed for the resonances in the vicinity of the heme 3-CH3 group in yeast iso-1 ferricytochrome c with changes in solution conditions, relative to the tuna and horse proteins, suggest that the region around Phe82 is more open and that movement of the Phe82 residue is less constrained in yeast ferricytochrome c. Finally, it is demonstrated here that both the heme 8-CH3 and the 7 alpha-CH resonances of yeast ferricytochrome c titrate with p2H and exhibit apparent pK values of approximately 7.0. The titrating group responsible for these spectral changes is proposed to be His39.     

One- and two-dimensional proton NMR studies of cys-102 S-methylated yeast isozyme-1 ferricytochrome c.

The effect of S-methylating cysteine-102 (cys-102) (SH----SSCH3) of yeast isozyme-1 (iso-1) ferricytochrome c has been studied using proton NMR spectroscopy. COSY, NOESY, and one-dimensional nuclear Overhauser effect (NOE) difference spectroscopies have all been used. The NMR spectrum of this derivative is very similar to that of native yeast iso-1 ferricytochrome c. The advantage of using the cys-102 S-methylated derivative is that it is unable to spontaneously dimerize in solution, like native iso-1 monomer does. This makes the derivative a simple, ideal protein for long NMR experiments. This work yields many proton resonance assignments for S-methylated yeast iso-1 monomer and confirms all of the assignments for iso-1 monomer that were previously made using only the one-dimensional NOE method.     

The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice

There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.     

Nuclear gene trees and the phylogenetic relationships of the mangabeys (Primates: Papionini)

Phylogenetic relationships of mangabeys within the Old World monkey tribe Papionini are inferred from analyses of nuclear DNA sequences from five unlinked loci. The following conclusions are strongly supported, based on congruence among trees derived for the five separate gene regions: (1) mangabeys are polyphyletic within the Papionini; (2) Cercocebus is the sister taxon to the genus Mandrillus; and (3) Lophocebus belongs to a clade with Papio and Theropithecus, with Papio as its most likely sister taxon. Morphologically based phylogenies positing mangabey monophyly were evaluated by mapping the sequences for each locus on these trees. The data seem to fit these trees poorly in both maximum-parsimony and likelihood analyses. Incongruence among nuclear gene trees occurred in the interrelationships among Lophocebus, Papio, and Theropithecus. Several factors that may account for this incongruence are discussed, including sampling error, random lineage sorting, and introgression.      

PPCMatrix: a PowerPC dotmatrix program to compare large genomic sequences against protein sequences

Summary : An interactive dotmatrix program for the MacOS was designed that allows comparison of DNA to protein sequences using nested 3-frame translations. Availability : Shareware, available at http://copan.bioz.unibas.ch/software/ Contact : burglin@ubaclu. unibas.ch      

SPL7013 Gel (VivaGel?) Retains Potent HIV-1 and HSV-2 Inhibitory Activity following Vaginal Administration in Humans

SPL7013 Gel (VivaGel^®) is a microbicide in development for prevention of HIV and HSV. This clinical study assessed retention and duration of antiviral activity following vaginal administration of 3% SPL7013 Gel in healthy women. Participants received 5 single doses of product with ≥5 days between doses. A cervicovaginal fluid (CVF) sample was collected using a SoftCup™ pre-dose, and immediately, or 1, 3, 12 or 24 h post-dose. HIV-1 and HSV-2 antiviral activities of CVF samples were determined in cell culture assays. Antiviral activity in the presence of seminal plasma was also tested. Mass and concentration of SPL7013 in CVF samples was determined. Safety was assessed by reporting of adverse events. Statistical analysis was performed using the Wilcoxon signed-rank test with Bonferroni adjustment; p≤0.003 was significant. Eleven participants completed the study. Inhibition of HIV-1 and HSV-2 by pre-dose CVF samples was negligible. CVF samples obtained immediately after dosing almost completely inhibited (median, interquartile range) HIV-1 [96% (95,97)] and HSV-2 [86% (85,94)], and activity was maintained in all women at 3 h (HIV-1 [96% (95,98), p = 0.9]; HSV-2 [94% (91,97), p = 0.005]). At 24 h, >90% of initial HIV-1 and HSV-2 inhibition was maintained in 6/11 women. SPL7013 was recovered in CVF samples obtained at baseline (46% of 105 mg dose). At 3 and 24 h, 22 mg and 4 mg SPL7013, respectively, were recovered. More than 70% inhibition of HIV-1 and HSV-2 was observed if there was >0.5 mg SPL7013 in CVF samples. High levels of antiviral activity were retained in the presence of seminal plasma. VivaGel was well tolerated with no signs or symptoms of vaginal, vulvar or cervical irritation reported. Potent antiviral activity was observed against HIV-1 and HSV-2 immediately following vaginal administration of VivaGel, with activity maintained for at least 3 h post-dose. The data provide evidence of antiviral activity in a clinical setting, and suggest VivaGel could be administered up to 3 h before coitus.

Trial Registration

The study is registered at ClinicalTrials.gov under identifier: {"type":"clinical-trial","attrs":{"text":"NCT00740584","term_id":"NCT00740584"}}NCT00740584