Nmr Solution Structure Of Plastocyanin From The Photosynthetic Prokaryote, Prochlorothrix Hollandica

The solution structure of a divergent plastocyanin (PC) from the photosynthetic prokaryote Prochlorothrix hollandica was determined by homonuclear H-1 NMR spectroscopy. Nineteen structures were calculated from 1222 distance restraints, yielding a family of structures having an average rmsd of 0.42 +/- 0.08 Angstrom, for backbone atoms and 0.71 +/- 0.07 Angstrom for heavy atoms to the mean structure. No distance constraint was violated by more than 0.26 Angstrom in the structure family. Despite the low number of conserved residues shared with other PC homologues, the overall folding pattern of P. hollandica PC is similar to other PCs, in that the protein forms a two-sheet beta-barrel tertiary structure. The greatest variability among the backbone structures is seen in the loop region from residues 47-60. The differences seen in the P. hollandica PC homologue likely arise due to a small deletion of 2-4 residues compared to the PC consensus; this yields a less extended loop containing a short alpha-helix from residues Ala52-Leu55. Additionally, the protein has an altered hydrophobic patch thought to be important in binding reaction partners. Whereas the backbone structure is very similar within the loops of the hydrophobic region, the presence of two unique residues (Tyr12 and Pro14) yields a structurally different hydrophobic surface likely important in binding P. hollandica Photosystem I

Reverse Micelles in Integral Membrane Protein Structural Biology by Solution NMR Spectroscopy

SummaryIntegral membrane proteins remain a significant challenge to structural studies by solution NMR spectroscopy. This is due not only to spectral complexity, but also because the effects of slow molecular reorientation are exacerbated by the need to solubilize the protein in aqueous detergent micelles. These assemblies can be quite large and require deuteration for optimal use of the TROSY effect. In principle, another approach is to employ reverse micelle encapsulation to solubilize the protein in a low-viscosity solvent in which the rapid tumbling of the resulting particle allows for use of standard triple-resonance methods. The preparation of such samples of membrane proteins is difficult. Using a 54 kDa construct of the homotetrameric potassium channel KcsA, we demonstrate a strategy that employs a hybrid surfactant to transfer the protein to the reverse micelle system

Oral and dermal toxicity of alkenones extracted from Isochrysis species

Author Posting. © Bioscience Research Institute, 2020. This article is posted here by permission of Bioscience Research Institute for personal use, not for redistribution. The definitive version was published in McIntosh, K., Sarver, J., Mell, K., Terrero, D. J., Ashby, C. R., Reddy, C., O’Neil, G., Ramapuram, J. B., & Tiwari, A. K. Oral and dermal toxicity of alkenones extracted from Isochrysis species. Frontiers in Bioscience-Landmark, 25(5), (2020): 817–837, https://doi.org/10.2741/4836.Isochrysis is commercially available marine algae used for animal feed, human nutrient supplements, and biodiesel. The Isochrysis species is one of five genera of haptophytes that produces unique, long-chain lipids known as alkenones that are promising new ingredients for green cosmetics, personal care products and pharmaceutical delivery. However, there is a lack of toxicity data for alkenones in animals, thus limiting their use in humans. In this study, we performed acute oral, acute dermal, and repeated 28-day dermal toxicity studies, using female SAS Sprague Dawley Rats. Our behavioral studies indicated that the specific alkenones had no overt behavioural effects at oral doses up to 4000 mg/kg. In the acute and chronic dermal toxicity studies, the alkenones produced less irritation and did not significantly damage the skin based on the Draize skin reaction scale and trans-epidermal water loss readings compared to the positive control, 1% sodium lauryl sulfate. Overall, our results indicated that alkenones are safe in Sprague Dawley rats, suggesting that they could be used for both oral and dermal formulations, although additional studies will be required.This work was supported by the Marine Biological Laboratory Woods Hole Oceanographic Institute (WHOI) under grant (N-126665-01, 2017), Washington Research Foundation, and University of Toledo start-up funding under a grant (F110760) to A.K.T. The authors declare no conflict of interest

Flavor Physics in an SO(10) Grand Unified Model

In supersymmetric grand-unified models, the lepton mixing matrix can possibly affect flavor-changing transitions in the quark sector. We present a detailed analysis of a model proposed by Chang, Masiero and Murayama, in which the near-maximal atmospheric neutrino mixing angle governs large new b -> s transitions. Relating the supersymmetric low-energy parameters to seven new parameters of this SO(10) GUT model, we perform a correlated study of several flavor-changing neutral current (FCNC) processes. We find the current bound on B(tau -> mu gamma) more constraining than B(B -> X_s gamma). The LEP limit on the lightest Higgs boson mass implies an important lower bound on tan beta, which in turn limits the size of the new FCNC transitions. Remarkably, the combined analysis does not rule out large effects in B_s-B_s-bar mixing and we can easily accomodate the large CP phase in the B_s-B_s-bar system which has recently been inferred from a global analysis of CDF and DO data. The model predicts a particle spectrum which is different from the popular Constrained Minimal Supersymmetric Standard Model (CMSSM). B(tau -> mu gamma) enforces heavy masses, typically above 1 TeV, for the sfermions of the degenerate first two generations. However, the ratio of the third-generation and first-generation sfermion masses is smaller than in the CMSSM and a (dominantly right-handed) stop with mass below 500 GeV is possible.Comment: 44 pages, 5 figures. Footnote and references added, minor changes, Fig. 2 corrected; journal versio

Supersymmetric constraints from Bs -> mu+mu- and B -> K* mu+mu- observables

We study the implications of the recent LHCb limit and results on Bs -> mu+mu- and B -> K* mu+mu- observables in the constrained SUSY scenarios. After discussing the Standard Model predictions and carefully estimating the theoretical errors, we show the constraining power of these observables in CMSSM and NUHM. The latest limit on BR(Bs -> mu+mu-), being very close to the SM prediction, constrains strongly the large tan(beta) regime and we show that the various angular observables from B -> K* mu+mu- decay can provide complementary information in particular for moderate tan(beta) values.Comment: 30 pages, 14 figure

Measuring V_ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons

The experimental prospects for precise measurements of the leptonic decays B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are very promising. Double ratios involving four of these decays can be defined in which the dependence on the values of the decay constants is essentially eliminated, thus enabling complementary measurements of the CKM matrix element V_ub with a small theoretical error. We quantify the experimental error in a possible future measurement of |V_ub| using this approach, and show that it is competitive with the anticipated precision from the conventional approaches. Moreover, it is shown that such double ratios can be more effective than the individual leptonic decays as a probe of the parameter space of supersymmetric models. We emphasize that the double ratios have the advantage of using |V_ub| as an input parameter (for which there is experimental information), while the individual decays have an uncertainty from the decay constants (e.g. f_B_s), and hence a reliance on theoretical techniques such as lattice QCD.Comment: 21 pages, 4 figure

Texture zeros for the standard model Quark mass matrices

ABSTRACT: A way of counting free parameters in the quark mass matrices of the standard model, including the constraints coming from weak basis transformations, is presented; this allow to understand the exact physical meaning of the parallel and non-parallel texture zeros which appear in some “ans¨atz” of the 3 × 3 quark mass matrices, including the CP violation phenomena in the analysis, it is shown why the six texture zeros are ruled out. Finally, a five texture zeros “ans¨atze”which properly copes with all experimental constrains, including the angles of the unitary triangle, is presented

Author Correction: Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

A Correction to this paper has been published: https://doi.org/10.1038/s41535-021-00314-