A guide to the twenty common amino acids

Have you ever thought about what makes up your body? Only 20 amino acids! Take a look at the graphic below, to discover the structure of each of these, plus information on the notation used to represent them.

Source: Compound Interest. Click to enlarge.

Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, although other elements are found in the side chains of certain amino acids. About 500 amino acids are known and can be classified in many ways. They can be classified according to the core structural functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid residues form the second-largest component (water is the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis.

In biochemistry, amino acids having both the amine and the carboxylic acid groups attached to the first (alpha-) carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids (generic formula H2NCHRCOOH in most cases, where R is an organic substituent known as a "side chain"); often the term "amino acid" is used to refer specifically to these. They include the 22 proteinogenic ("protein-building") amino acids, which combine into peptide chains ("polypeptides") to form the building-blocks of a vast array of proteins. These are all L-stereoisomers ("left-handed" isomers), although a few D-amino acids ("right-handed") occur in bacterial envelopes, as a neuromodulator (D-serine), and in some antibiotics. 

Twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as "standard" amino acids. The other two ("non-standard" or "non-canonical") are selenocysteine (present in many noneukaryotes as well as most eukaryotes, but not coded directly by DNA), and pyrrolysine (found only in some archea and one bacterium). Pyrrolysine and selenocysteine are encoded via variant codons; for example, selenocysteine is encoded by stop codon and SECIS element. N-formylmethionine (which is often the initial amino acid of proteins in bacteria, mitochondria, and chloroplasts) is generally considered as a form of methionine rather than as a separate proteinogenic amino acid. Codon–tRNA combinations not found in nature can also be used to "expand" the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids.

Many important proteinogenic and non-proteinogenic amino acids have biological functions. For example, in the human brain, glutamate (standard glutamic acid) and gamma-amino-butyric acid ("GABA", non-standard gamma-amino acid) are, respectively, the main excitatory and inhibitory neurotransmitters. Hydroxyproline, a major component of the connective tissue collagen, is synthesised from proline. Glycine is a biosynthetic precursor to porphyrins used in red blood cells. Carnitine is used in lipid transport.

Nine proteinogenic amino acids are called "essential" for humans because they cannot be created from other compounds by the human body and so must be taken in as food. Others may be conditionally essential for certain ages or medical conditions. Essential amino acids may also differ between species.

Because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology. Industrial uses include the production of drugs, biodegradable plastics, and chiral catalysts.

For more information visit:-

http://www.compoundchem.com/2014/09/16/aminoacids/

https://en.wikipedia.org/wiki/Amino_acid

http://www.prlabs.co.uk/lab-supplies.php?N=l-arginine-for-biochemistry&Id=22533

Diesels pollute more than lab tests detect

Because of testing inefficiencies, maintenance inadequacies and other factors, cars, trucks and buses worldwide emit 4.6 million tons more harmful nitrogen oxide (NOx) than standards allow, according to a new study co-authored by University of Colorado Boulder researchers.

The study, published in Nature, shows these excess emissions alone lead to 38,000 premature deaths annually worldwide, including 1,100 deaths in the United States.

The findings reveal major inconsistencies between what vehicles emit during testing and what they emit in the real world - a problem that's far more severe, said the researchers, than the incident in 2015, when federal regulators discovered Volkswagen had been fitting millions of new diesel cars with "defeat devices."

Red Diesel Tank, by Meena Kadri [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

The devices sense when a vehicle is undergoing testing and reduce emissions to comply with government standards. Excess emissions from defeat devices have been linked to about 50 to 100 U.S. deaths per year, studies show.

"A lot of attention has been paid to defeat devices, but our work emphasizes the existence of a much larger problem," said Daven Henze, an associate professor of mechanical engineering at CU Boulder who, along with postdoctoral researcher Forrest Lacey, contributed to the study. "It shows that in addition to tightening emissions standards, we need to be attaining the standards that already exist in real-world driving conditions."

The research was conducted in partnership with the International Council on Clean Transportation, a Washington, D.C.-based nonprofit organization, and Environmental Health Analytics LLC.

For the paper, the researchers assessed 30 studies of vehicle emissions under real-world driving conditions in 11 major vehicle markets representing 80 percent of new diesel vehicle sales in 2015. Those markets include Australia, Brazil, Canada, China, the European Union, India, Japan, Mexico, Russia, South Korea and the United States.

They found that in 2015, diesel vehicles emitted 13.1 million tons of NOx, a chemical precursor to particulate matter and ozone. Exposure in humans can lead to heart disease, stroke, lung cancer and other health problems. Had the emissions met standards, the vehicles would have emitted closer to 8.6 million tons of NOx.

Heavy-duty vehicles, such as commercial trucks and buses, were by far the largest contributor worldwide, accounting for 76 percent of the total excess NOx emissions.

Henze used computer modeling and NASA satellite data to simulate how particulate matter and ozone levels are, and will be, impacted by excess NOx levels in specific locations. The team then computed the impacts on health, crops and climate.

"The consequences of excess diesel NOx emissions for public health are striking," said Susan Anenberg, co-lead author of the study and co-founder of Environmental Health Analytics LLC.

China suffers the greatest health impact with 31,400 deaths annually attributed to diesel NOx pollution, with 10,700 of those deaths linked to excess NOx emissions beyond certification limits. In Europe, where diesel-passenger cars are common, 28,500 deaths annually are attributed to diesel NOx pollution, with 11,500 of those deaths linked to excess emissions.

The study projects that by 2040, 183,600 people will die prematurely each year due to diesel vehicle NOx emissions unless governments act.

The authors say emission certification tests, both prior to sale and by vehicle owners, could be more accurate if they were to simulate a broader variety of speeds, driving styles and ambient temperatures. Some European countries now use portable testing devices that track emissions of a car in motion.

"Tighter vehicle emission standards coupled with measures to improve real-world compliance could prevent hundreds of thousands of early deaths from air pollution-related diseases each year," said Anenberg.

For more information, visit:-

https://www.sciencedaily.com/releases/2017/05/170515111557.htm

http://www.prlabs.co.uk/lab-supplies.php?N=gastube-nitrogen-oxide-airtec-002-2ppm&Id=11713

https://commons.wikimedia.org/wiki/File:Red_diesel_tank.jpg

Mission control: salty diet makes you hungry, not thirsty

We've all heard it: eating salty foods makes you thirstier. But what sounds like good nutritional advice turns out to be an old-wives' tale. In a study carried out during a simulated mission to Mars, an international group of scientists has found exactly the opposite to be true. "Cosmonauts" who ate more salt retained more water, weren't as thirsty, and needed more energy.

Salt shaker, by Dubravko Sorić SoraZG on Flickr [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

For some reason, no one had ever carried out a long-term study to determine the relationship between the amount of salt in a person's diet and his drinking habits. Scientists have known that increasing a person's salt intake stimulates the production of more urine - it has simply been assumed that the extra fluid comes from drinking. Not so fast! say researchers from the German Aerospace Center (DLR), the Max Delbrück Center for Molecular Medicine (MDC), Vanderbilt University and colleagues around the world. Recently they took advantage of a simulated mission to Mars to put the old adage to the test. Their conclusions appear in two papers in the current issue of The Journal of Clinical Investigation.

What does salt have to do with Mars? Nothing, really, except that on a long space voyage conserving every drop of water might be crucial. A connection between salt intake and drinking could affect your calculations - you wouldn't want an interplanetary traveler to die because he liked an occasional pinch of salt on his food. The real interest in the simulation, however, was that it provided an environment in which every aspect of a person's nutrition, water consumption, and salt intake could be controlled and measured.

The studies were carried out by Natalia Rakova (MD, PhD) of the Charité and MDC and her colleagues. The subjects were two groups of 10 male volunteers sealed into a mock spaceship for two simulated flights to Mars. The first group was examined for 105 days; the second over 205 days. They had identical diets except that over periods lasting several weeks, they were given three different levels of salt in their food.

The results confirmed that eating more salt led to a higher salt content in urine - no surprise there. Nor was there any surprise in a correlation between amounts of salt and overall quantity of urine. But the increase wasn't due to more drinking - in fact, a salty diet caused the subjects to drink less. Salt was triggering a mechanism to conserve water in the kidneys.

Before the study, the prevailing hypothesis had been that the charged sodium and chloride ions in salt grabbed onto water molecules and dragged them into the urine. The new results showed something different: salt stayed in the urine, while water moved back into the kidney and body. This was completely puzzling to Prof. Jens Titze, MD of the University of Erlangen and Vanderbilt University Medical Center and his colleagues. "What alternative driving force could make water move back?" Titze asked.

Experiments in mice hinted that urea might be involved. This substance is formed in muscles and the liver as a way of shedding nitrogen. In mice, urea was accumulating in the kidney, where it counteracts the water-drawing force of sodium and chloride. But synthesizing urea takes a lot of energy, which explains why mice on a high-salt diet were eating more. Higher salt didn't increase their thirst, but it did make them hungrier. Also the human "cosmonauts" receiving a salty diet complained about being hungry.

The project revises scientists' view of the function of urea in our bodies. "It's not solely a waste product, as has been assumed," Prof. Friedrich C. Luft, MD of the Charité and MDC says. "Instead, it turns out to be a very important osmolyte - a compound that binds to water and helps transport it. Its function is to keep water in when our bodies get rid of salt. Nature has apparently found a way to conserve water that would otherwise be carried away into the urine by salt."

The new findings change the way scientists have thought about the process by which the body achieves water homeostasis - maintaining a proper amount and balance. That must happen whether a body is being sent to Mars or not. "We now have to see this process as a concerted activity of the liver, muscle and kidney," says Jens Titze.

"While we didn't directly address blood pressure and other aspects of the cardiovascular system, it's also clear that their functions are tightly connected to water homeostasis and energy metabolism."

For more information visit:-

https://www.sciencedaily.com/releases/2017/04/170417182920.htm

http://www.prlabs.co.uk/lab-supplies.php?N=carboxymethylcellulose-sodium-salt&Id=57938
https://en.wikipedia.org/wiki/Salt

Dwarf star 200 light years away contains life's building blocks

Many scientists believe the Earth was dry when it first formed, and that the building blocks for life on our planet - carbon, nitrogen and water - appeared only later as a result of collisions with other objects in our solar system that had those elements.

Today, a UCLA-led team of scientists reports that it has discovered the existence of a white dwarf star whose atmosphere is rich in carbon and nitrogen, as well as in oxygen and hydrogen, the components of water. The white dwarf is approximately 200 light years from Earth and is located in the constellation Boötes.

The Earth seen from Apollo 17. By NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans [Public domain or Public domain], via Wikimedia Commons

Benjamin Zuckerman, a co-author of the research and a UCLA professor of astronomy, said the study presents evidence that the planetary system associated with the white dwarf contains materials that are the basic building blocks for life. And although the study focused on this particular star - known as WD 1425+540 - the fact that its planetary system shares characteristics with our solar system strongly suggests that other planetary systems would also.

"The findings indicate that some of life's important preconditions are common in the universe," Zuckerman said.

The scientists report that a minor planet in the planetary system was orbiting around the white dwarf, and its trajectory was somehow altered, perhaps by the gravitational pull of a planet in the same system. That change caused the minor planet to travel very close to the white dwarf, where the star's strong gravitational field ripped the minor planet apart into gas and dust. Those remnants went into orbit around the white dwarf - much like the rings around Saturn, Zuckerman said - before eventually spiraling onto the star itself, bringing with them the building blocks for life.

The researchers think these events occurred relatively recently, perhaps in the past 100,000 years or so, said Edward Young, another co-author of the study and a UCLA professor of geochemistry and cosmochemistry. They estimate that approximately 30 percent of the minor planet's mass was water and other ices, and approximately 70 percent was rocky material.

The research suggests that the minor planet is the first of what are likely many such analogs to objects in our solar system's Kuiper belt. The Kuiper belt is an enormous cluster of small bodies like comets and minor planets located in the outer reaches of our solar system, beyond Neptune. Astronomers have long wondered whether other planetary systems have bodies with properties similar to those in the Kuiper belt, and the new study appears to confirm for the first time that one such body exists.

White dwarf stars are dense, burned-out remnants of normal stars. Their strong gravitational pull causes elements like carbon, oxygen and nitrogen to sink out of their atmospheres and into their interiors, where they cannot be detected by telescopes.

The research, published in the Astrophysical Journal Letters, describes how WD 1425+540 came to obtain carbon, nitrogen, oxygen and hydrogen. This is the first time a white dwarf with nitrogen has been discovered, and one of only a few known examples of white dwarfs that have been impacted by a rocky body that was rich in water ice.

"If there is water in Kuiper belt-like objects around other stars, as there now appears to be, then when rocky planets form they need not contain life's ingredients," said Siyi Xu, the study's lead author, a postdoctoral scholar at the European Southern Observatory in Germany who earned her doctorate at UCLA.

"Now we're seeing in a planetary system outside our solar system that there are minor planets where water, nitrogen and carbon are present in abundance, as in our solar system's Kuiper belt," Xu said. "If Earth obtained its water, nitrogen and carbon from the impact of such objects, then rocky planets in other planetary systems could also obtain their water, nitrogen and carbon this way."

A rocky planet that forms relatively close to its star would likely be dry, Young said.

"We would like to know whether in other planetary systems Kuiper belts exist with large quantities of water that could be added to otherwise dry planets," he said. "Our research suggests this is likely."

According to Zuckerman, the study doesn't settle the question of whether life in the universe is common.

"First you need an Earth-like world in its size, mass and at the proper distance from a star like our sun," he said, adding that astronomers still haven't found a planet that matches those criteria.

The researchers observed WD 1425+540 with the Keck Telescope in 2008 and 2014, and with the Hubble Space Telescope in 2014. They analyzed the chemical composition of its atmosphere using an instrument called a spectrometer, which breaks light into wavelengths. Spectrometers can be tuned to the wavelengths at which scientists know a given element emits and absorbs light; scientists can then determine the element's presence by whether it emits or absorbs light of certain characteristic wavelengths. In the new study, the researchers saw the elements in the white dwarf's atmosphere because they absorbed some of the background light from the white dwarf.

For more information visit:-

https://www.sciencedaily.com/releases/2017/02/170209163852.htm

http://www.prlabs.co.uk/lab-supplies.php?N=carbon-capsule&Id=44459

https://en.wikipedia.org/wiki/Earth

Air pollution causes wrinkles and premature ageing, new research shows

Air pollution is prematurely ageing the faces of city dwellers by accelerating wrinkles and age spots, according to emerging scientific research.

The effects of toxic fumes on skin are being seen in both western cities, such as London and New York, as well as in more visibly polluted Asian cities and in some cases may be the primary cause of ageing. The pollution is also being linked to worsening skin conditions such as eczema and hives.

The scientific discoveries are now driving the world’s biggest cosmetics companies to search for solutions, including medicine-like compounds that directly block the biological damage. But doctors warn that some common skin care routines, such as scrubs, make the damage from air pollution even worse.

Poisonous air is already known to cause millions of early deaths from lung and heart diseases and has been linked to diabetes and mental health problems. But perhaps its most visible impact, the damage caused to skin, is just beginning to be understood.

“With traffic pollution emerging as the single most toxic substance for skin, the dream of perfect skin is over for those living and working in traffic-polluted areas unless they take steps to protect their skin right now,” said Dr Mervyn Patterson, a cosmetic doctor at Woodford Medical clinics in the UK.

“Unless people do more they will end up wearing the pollution on their faces in 10 years’ time. It is definitely something people now need to take seriously.”

Nitrogen dioxide diffusion tube for air quality monitoring.By Etan J. Tal, via Wikimedia Commons.

Prof Jean Krutmann, director at the Leibniz Research Institute for Environmental Medicine in Germany, said: “UV [damage from the sun] was really the topic in skin protection for the last 20-30 years. Now I think air pollution has the potential to keep us busy for the next few decades.”

Air pollution in urban areas, much of which comes from traffic, includes tiny particles called PMs, nitrogen dioxide (NO2) and chemicals such as polycyclic aromatic hydrocarbons (PAHs). “What is very clear is that PMs are a problem for skin,” said Krutmann, whose work has shown PMs increase age spots and wrinkles.

But one of the his newest studies showed NO2 also increases ageing. They studied people in both Germany and China and discovered that age spots on their cheeks increased by 25% with a relatively small increase in pollution, 10 microgrammes of NO2 per cubic metre. Many parts of the UK have illegally high levels of NO2, with London breaking its annual limit in the first week of 2016, with levels reaching over 200 microgrammes of NO2 per cubic metre.

Krutmann said other factors, such as UV exposure, nutrition and smoking contribute to ageing: “But what we can say is that, at least for the pigment spots on the cheeks, it seems air pollution is the major driver.”

“It is not a problem that is limited to China or India – we have it in Paris, in London, wherever you have larger urban agglomerations you have it,” he said. “In Europe everywhere is so densely populated and the particles are being distributed by the wind, so it is very difficult to escape from the problem.”

The accelerated skin ageing was seen in relatively young people and Patterson said: “If you are seeing these changes in middle age, these are worrying trends.”

Other recent research is summed up in a review paper in the journal Frontiers in Environmental Science, which concluded: “Prolonged or repetitive exposure to high levels of these [air] pollutants may have profound negative effects on the skin.”

Understanding exactly how air pollution causes the skin damage is at an early stage, according to Krutmann: “We are just now dipping into the mechanisms.” But many of the pollutants are known to pass easily through the skin and cause a variety of impacts.

“These agents have a very irritating effect and once they get into the skin, they activate multiple pathways of inflammation,” said Patterson. “Some pathways ignite the melanocytes, which create far too much pigment and end up giving you unwanted sun spots.”

“Other pathways ignite messengers that make blood vessels grow, that’s what results in increased redness and potentially rosacea,” he said. “Also, if you damage skin, it goes into repair mode and excites enzymes which re-adsorb damaged collagen. When you have too much chronic inflammation, these enzymes remove more collagen than your skin can create. This produces skin laxity and that’s where fine lines and wrinkles come in.”

Dr Debra Jaliman, a skin expert based in New York City, says her patients are now worrying about the impact of air pollution on their skin, which she said can cause darkening of the skin and acne-like eruptions, as well as ageing.

“At the moment, there are not many products for prevention [of air pollution damage], however it may be a trend in the coming years as it becomes a much bigger issue,” she said.

Major beauty companies have begun their own research and are launching the first products formulated to battle skin damage from toxic air. Dr Frauke Neuser, senior scientist for Olay, a Procter and Gamble brand, has run studies showing significantly lower skin hydration in people living in polluted areas and lab studies showing that diesel fumes and PMs cause inflammation in skin cells.

Her team then screened for ingredients that could counteract some of the damaging effects. “We found niacinamide - vitamin B3 - to be particularly effective,” she said. “We have recently increased its level in several products by as much as 40%.”

Frauke’s work has also shown direct correlations between spikes in PM air pollution in Beijing and an increase in hospital visits by people with skin conditions including hives. “This indicates that not only skin ageing but also skin health are affected by air pollution,” she said.

L’Oreal, another cosmetics giant, published a medical study in 2015 showing that eczema and hives were more common in people in Mexico exposed to higher levels of air pollution, a conclusion supported by separate research in Canada. “The next step is to understand more deeply the environment-induced damages, in order to develop skin ageing prevention routines and products,” said Dr Steve Shiel, scientific director at L’Oreal.

Clinique, a big makeup brand, has already launched a sonic face cleansing brush it claims better removes pollution. “This [air pollution] is not going to go away. This is not a problem that is easily fixed,” said Janet Pardo at Clinique.

However, researchers are now working on medicine-like compounds that block the damage from air pollution from occurring in the first place. Krutmann’s lab helped Symrise, one of the world’s biggest suppliers of cosmetics ingredients, identify one, though the lab has no commercial stake in the product, which is called SymUrban.

“We found one molecule that can do the job,” he said, and it is now being registered as cosmetic ingredient. “In a few years from now I expect we will see cosmetic products that can specifically protect against skin ageing from air pollution.”

Patterson said it is possible for people to give themselves some protection now. “You don’t have to sit back passively and put up with it. You can take sensible, easy steps that will make a difference.”

“If your skin is really healthy, it is quite a good barrier,” he said, explaining that the top layer is like a roof - flattened cells like tiles separated by protective lipids.

“Certain skin care products are very disruptive to the surface of the skin,” he warned. “So a darling of the industry is retinoids, but these have a very profound negative effect on barrier function. Another darling of the industry is glycolic acid, but it is also very disruptive to the external skin barrier. People think these are good skin care, making the skin look smoother, but they are not helpful for the overall health of the skin barrier.”

Patterson is also dismissive of face scrubs: “The skin is trying its damnedest to make this wonderful defence mechanism and what do women and men do? They scrub the hell out of it. It just doesn’t make sense.” He said products that help repair the skin barrier, by delivering the pre-cursor lipids the cells need, are beneficial, as are ones that tackle inflammation.

“You can also put on a very nice physical shield in the form of good quality mineral makeup,” he said. “That produces an effect like a protective mesh and probably has some trapping effect, protecting against the initial penetration of particles. But you also need always to try to remove that shield in the evening, washing the slate clean every night.”

For more information visit:-

https://www.theguardian.com/environment/2016/jul/15/air-pollution-causes-wrinkles-and-premature-ageing-new-research-shows

http://www.prlabs.co.uk/lab-supplies.php?N=total-nitrogen-lr-set&Id=61458

On this day in history - the moon landing goal was announced

In 1961, the formal announcement of an American lunar landing was made by President John F. Kennedy speaking to the Congress: “I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space program in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.” 

Since, a total of twelve men have landed on the Moon. This was accomplished with two US pilot-astronauts flying a Lunar Module on each of six NASA missions across a 41-month time span starting on 20 July 1969 UTC, with Neil Armstrong and Buzz Aldrin on Apollo 11, and ending on 14 December 1972 UTC with Gene Cernan and Jack Schmitt on Apollo 17. Cernan was the last to step off the lunar surface.

Lunar crater Daedalus on the Moon's far side

All Apollo lunar missions had a third crew member who remained on board the Command Module. The last three missions had a rover for increased mobility.

The atmosphere of the moon

The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 metric tons (9.8 long tons; 11 short tons). The surface pressure of this small mass is around 3 × 10−15 atm (0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, the release of atoms from the bombardment of lunar soil by solar wind ions. Elements that have been detected include sodium and potassium, produced by sputtering, which are also found in the atmospheres of Mercury and Io; helium-4 and neon from the solar wind; and argon-40, radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle.

The absence of such neutral species (atoms or molecules) as oxygen, nitrogen, carbon, hydrogen and magnesium, which are present in the regolith, is not understood. Water vapour has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith. These gases can either return into the regolith due to the Moon's gravity or be lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field.

For more information visit:-

http://www.todayinsci.com/5/5_25.htm

https://en.wikipedia.org/wiki/Moon

https://www.prlabs.co.uk/lab-supplies.php?N=ammonia-nitrogen-10ml-set&Id=61457