Oxidation states of individual metal atoms within a metalloprotein can be assigned by examining X-ray absorption edges, which shift to higher energy for progressively more positive valence numbers. Indeed, X-ray crystallography is well suited for such a measurement, owing to its ability to spatially resolve the scattering contributions of individual metal atoms that have distinct electronic environments contributing to protein function. However, as the magnitude of the shift is quite small, about +2 eV per valence state for iron, it has only been possible to measure the effect when performed with monochromated X-ray sources at synchrotron facilities with energy resolutions in the range 2–3 × 10−4 (ΔE/E). This paper tests whether X-ray free-electron laser (XFEL) pulses, which have a broader bandpass (ΔE/E = 3 × 10−3) when used without a monochromator, might also be useful for such studies. The program nanoBragg is used to simulate serial femtosecond crystallography (SFX) diffraction images with sufficient granularity to model the XFEL spectrum, the crystal mosaicity and the wavelength-dependent anomalous scattering factors contributed by two differently charged iron centers in the 110-amino-acid protein, ferredoxin. Bayesian methods are then used to deduce, from the simulated data, the most likely X-ray absorption curves for each metal atom in the protein, which agree well with the curves chosen for the simulation. The data analysis relies critically on the ability to measure the incident spectrum for each pulse, and also on the nanoBragg simulator to predict the size, shape and intensity profile of Bragg spots based on an underlying physical model that includes the absorption curves, which are then modified to produce the best agreement with the simulated data. This inference methodology potentially enables the use of SFX diffraction for the study of metalloenzyme mechanisms and, in general, offers a more detailed approach to Bragg spot data reduction.

Monoheme c-type cytochromes are important electron transporters in all domains of life. They possess a common fold hallmarked by three α-helices that surround a covalently attached heme. An intriguing feature of many monoheme c-type cytochromes is their capacity to form oligomers by exchanging at least one of their α-helices, which is often referred to as 3D domain swapping. Here, the crystal structure of NirC, a c-type cytochrome co-encoded with other proteins involved in nitrite reduction by the opportunistic pathogen Pseudomonas aeruginosa, has been determined. The crystals diffracted anisotropically to a maximum resolution of 2.12 Å (spherical resolution of 2.83 Å) and initial phases were obtained by Fe-SAD phasing, revealing the presence of 11 NirC chains in the asymmetric unit. Surprisingly, these protomers arrange into one monomer and two different types of 3D domain-swapped dimers, one of which shows pronounced asymmetry. While the simultaneous observation of monomers and dimers probably reflects the interplay between the high protein concentration required for crystallization and the structural plasticity of monoheme c-type cytochromes, the identification of conserved structural motifs in the monomer together with a comparison with similar proteins may offer new leads to unravel the unknown function of NirC.

Quantum beats in fluorescence decay from Zeeman-split magnetic sublevels have been measured for helium Rydberg states excited by synchrotron radiation. The Zeeman quantum beats observed in this prototypical case were fitted with an equation from a theoretical formulation. It is proposed that Zeeman quantum beat measurement can be a useful way to simply evaluate the polarization characteristics of extreme ultraviolet light.

Non-native plant species pose a significant threat to the natural ecosystems of the United States. Many of these invasive plants are escapees from gardens and […]

The post Escape of the invasives: Top six invasive plant species in the United States appeared first on Smithsonian Insider.

Immigration benefits the U.S. economy overall and has little negative effect on the income and job opportunities of most native-born Americans, says a new report by a panel of the National Research Council.

Policymakers, employers, and educational institutions should take steps to strengthen the nation’s skilled technical workforce, says a new report from the National Academies of Sciences, Engineering, and Medicine.

NASA’s large strategic missions like the Hubble Space Telescope, the Curiosity rover on Mars, and the Terra Earth observation satellite are essential to maintaining the United States’ global leadership in space exploration and should continue to be a primary component of a balanced space science program that includes large, medium, and smaller missions, says a new report by the National Academies of Sciences, Engineering, and Medicine.

For his pioneering role in national health policy and health services research, the National Academy of Medicine today announced Stuart Altman is the recipient of the 2018 Gustav O. Lienhard Award for Advancement of Health Care.

The Census Bureau says it will continue its relaunch of limited field operations for the 2020 census next week in some rural communities in nine states.; Credit: Matt Rourke/AP

The Census Bureau says it is continuing the gradual relaunch of limited field operations for the 2020 census next week in nine states where the coronavirus pandemic forced the hand-delivery of paper forms in rural areas to be suspended in mid-March.

On May 13, some local census offices in Florida, Georgia, Kansas, Kentucky, Missouri, North Carolina, Oregon, Pennsylvania and Washington are scheduled to restart that fieldwork, according to an updated schedule the bureau published on its website Friday.

All workers are expected to be trained in CDC guidance in preventing the spread of COVID-19, and besides a new reusable face mask for every 10 days worked and a pair of gloves for each work day, the bureau has ordered 2 ounces of hand sanitizer for each census worker conducting field operations, the bureau tells NPR in an email.

The announcement means more households that receive their mail at post office boxes or drop points are expected to find paper questionnaires left outside their front doors soon. In areas where access to the online census form at my2020census.gov can be spotty, paper forms help ensure that all homes can participate in the once-a-decade head count of every U.S. resident.

The results are used to determine how many congressional seats and Electoral College votes each state gets through 2030. They also guide the redrawing of voting districts and the distribution of an estimated $1.5 trillion a year in federal funding for schools, roads and other public services in local communities.

The Census Bureau also announced on Friday that fingerprinting for newly hired census workers will pick up again next week in and around Philadelphia, Seattle, Portland, Ore., and Pittsburgh. With responses from close to 86 million households bringing the national self-response rate to just over 58% as of Thursday, the federal government is relying on staffing up with enough door knockers to complete the count. They're currently scheduled to make in-person visits to unresponsive homes starting in August.

Last month, Census Bureau officials asked Congress to consider pushing back the legal deadlines for delivering census data used to reapportion House seats and reshape voting maps by four months because of the delays brought on by the coronavirus.

In a letter to U.S. Senate leaders released on Friday, more than a dozen Democratic senators led by Brian Schatz of Hawaii are calling for the next COVID-19 relief package to include more funding and requirements for the Census Bureau "to keep both field workers and the public safe while conducting this constitutionally required enumeration."

This content is from Southern California Public Radio. View the original story at SCPR.org.

Species surveys should be standardised across Member State borders to assess conservation status accurately, a new study concludes. The researchers assessed the conservation status of the Eurasian otter across the Republic of Ireland–UK border, finding that it was favourable for the whole island of Ireland. This provides a case study of surveys designed to provide data that is comparable across borders, say the researchers.

Pesticide-related poisonings in EU Member States must be reported to the European Commission under current legislation, but there is no standard information collection and reporting system. A new system has been proposed, which harmonises data collection, categorisation and reporting, enabling exposure data to be compared among Member States. The new system would improve the monitoring of pesticides in Europe and aid the identification of emerging problems.

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Professor Su Guaning, President Emeritus of Nanyang Technological University, Singapore (NTU Singapore), has been elected to the United States' National Academy of Engineering (NAE)....

California and the Northeast love wine, Colorado and the Midwest quaff beer.

There's a lot to sort out in Libya's post-Gadhafi era, but there should be good news for the American consumer.

Skip the stores and head outdoors to a nearby state park.

As the United States seeks to rely less on imported oil, a few states are leading the charge in the renewable energy revolution.

Here's a graphical glimpse at America's most endangered wildlife, where they live and how many are left.

Is a kinder, gentler Exxon/Mobil — with Rex Tillerson at its helm — really changing its stripes?

As Obama plans for an energy makeover, his Department of Energy is still focused on nuclear weapons.

Green States MNN columnist Peter Dykstra asks whether environmental lobbying will be changed along with other government lobbying through Obama ethics reform.

A few years ago, when Janet Jackson “oopsed” her way into Super Bowl and Federal Communications Commission history, 140 million viewers of the biggest game

How a new YouTube video is getting us to think that when it comes to the future of water, it seems the glass is half empty.

A little over a year ago, in a very different world, three economic titans issued "The Carbon Principles," a list of investment guidelines for electric power pr

Nonprofit groups function a little differently than the rest of the business world. Salaries tend to be a bit lower; passions about the mission of the place you

Diamorpha Smallii is the taxonomic name. It has another name, Small's Stonecrop. But in Georgia, we call it Red Stuff.

Nature has a great way of giving clues to the clueless. When spring arrives a little earlier, and fall stays a bit later, it’s not necessarily a good thing.

The brown tree snakes have completely taken over on Guam. The snakes conquered an ecosystem where there were no natural enemies.

It's amazing to see how nature has made itself at home on the abandoned Southerness Golf Club course.

The potent allure or either money or ideology, or both, leads a lot of people to devote their lives to either impeding environmental progress, or enabling envir

The Energy Policy Act of 2005 offers a 50-cent-per-gallon tax credit for entrepreneurs who mix biomass or ethanol with conventionally taxed fossil fuels.

Here's a quick look by the numbers at where we're in trouble on key environmental issues. I've borrowed a bit from the style of the Harper's Index, and a bit fr

Every once in a while, humanity manages to do something so sublimely awful that all we can do is laugh. Next month, we’ll mark the 40th anniversary of one of

It's what you've been waiting for. Peter Dykstra lists his picks for America’s nine greatest environmental heroes.

Baby will be the youngest person to see every state.

The bat-killing fungal infection known as white-nose syndrome has been found in two new U.S. states.

New Hampshire, New Mexico, Montana, Minnesota, and Utah have completed 30% of their home weatherization projects, unlocking additional program funding.

Sales of plug-ins are a fraction of cars sold, but governments and industry are doing their part to make that number grow.

The longhorned tick, native to Asia, is first new invasive tick to be found in U.S. in 50 years.

Indian automaker Tata will be bringing the inexpensive Nano to the U.S. within three years.

Job-creating grants are making their way to a swing state near you!

Massive investment coupled with falling prices has created a perfect renewable storm in the Golden State.

Rodney Smith Jr. launched a grassroots movement, Raising Men Lawn Care Service, to change the world with his lawn mower.

Dozens of countries have banned cosmetics tested on animals, and now more U.S. states are doing the same.

The Smiley family, from 1869 to the present, has run the Mohonk Mountain House, a gorgeous throwback of a resort hotel that I can no longer afford to visit abou

John Glen said the government is in continual dialogue with insurance sector as he restates companies without the right cover will require support from elsewhere.

Concussion Settlement Payouts Delayed; Eligible Former Players Can Receive a Portion of Settlement Funding Now

Sator Soccer is a family-owned business that has been dedicated to helping soccer communities bring pro-grade quality and safety to the field since 1997.

Criminal justice systems are being modified in numerous states within the USA. But are their new policies really working?

Engineering leader established engineering practices that paved the way for Colorado's growth