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

Blood-repellent materials: A new approach to medical implants

Medical implants like stents, catheters and tubing introduce risk for blood clotting and infection - a perpetual problem for many patients.

Colorado State University engineers offer a potential solution: A specially grown, "superhemophobic" titanium surface that's extremely repellent to blood. The material could form the basis for surgical implants with lower risk of rejection by the body.

Titanium (mineral concentrate). Public Domain, https://commons.wikimedia.org/w/index.php?curid=323468

It's an outside-the-box innovation achieved at the intersection of two disciplines: biomedical engineering and materials science. The work, recently published in Advanced Healthcare Materials, is a collaboration between the labs of Arun Kota, assistant professor of mechanical engineering and biomedical engineering; and Ketul Popat, associate professor in the same departments.

Kota, an expert in novel, "superomniphobic" materials that repel virtually any liquid, joined forces with Popat, an innovator in tissue engineering and bio-compatible materials. Starting with sheets of titanium, commonly used for medical devices, their labs grew chemically altered surfaces that act as perfect barriers between the titanium and blood. Their teams conducted experiments showing very low levels of platelet adhesion, a biological process that leads to blood clotting and eventual rejection of a foreign material.

A material "phobic" (repellent) to blood might seem counterintuitive, the researchers say, as often biomedical scientists use materials "philic" (with affinity) to blood to make them biologically compatible. "What we are doing is the exact opposite," Kota said. "We are taking a material that blood hates to come in contact with, in order to make it compatible with blood." The key innovation is that the surface is so repellent, that blood is tricked into believing there's virtually no foreign material there at all.

The undesirable interaction of blood with foreign materials is an ongoing problem in medical research, Popat said. Over time, stents can form clots, obstructions, and lead to heart attacks or embolisms. Often patients need blood-thinning medications for the rest of their lives - and the drugs aren't foolproof.

"The reason blood clots is because it finds cells in the blood to go to and attach," Popat said. "Normally, blood flows in vessels. If we can design materials where blood barely contacts the surface, there is virtually no chance of clotting, which is a coordinated set of events. Here, we're targeting the prevention of the first set of events."

The researchers analyzed variations of titanium surfaces, including different textures and chemistries, and they compared the extent of platelet adhesion and activation. Fluorinated nanotubes offered the best protection against clotting, and they plan to conduct follow-up experiments.

Growing a surface and testing it in the lab is only the beginning, the researchers say. They want to continue examining other clotting factors, and eventually, to test real medical devices.

For more information visit:-

https://www.sciencedaily.com/releases/2017/01/170118163731.htm

http://www.prlabs.co.uk/lab-supplies.php?N=titanium-1000ppm-for-icp&Id=60243

Zinc eaten at levels found in biofortified crops reduces 'wear and tear' on DNA

A new study by researchers from the UCSF Benioff Children's Hospital Research Institute (CHORI) shows that a modest 4 milligrams of extra zinc a day in the diet can have a profound, positive impact on cellular health that helps fight infections and diseases. This amount of zinc is equivalent to what biofortified crops like zinc rice and zinc wheat can add to the diet of vulnerable, nutrient deficient populations.

The study, published in the American Journal of Clinical Nutrition, was led by CHORI Senior Scientist Janet King, PhD. King and her team are the first to show that a modest increase in dietary zinc reduces oxidative stress and damage to DNA.

Zinc Acetate. By Chemical interest (Own work (Original text: self-made)) [Public domain], via Wikimedia Commons

"We were pleasantly surprised to see that just a small increase in dietary zinc can have such a significant impact on how metabolism is carried out throughout the body," says King. "These results present a new strategy for measuring the impact of zinc on health and reinforce the evidence that food-based interventions can improve micronutrient deficiencies worldwide."

Zinc is ubiquitous in our body and facilitates many functions that are essential for preserving life. It plays a vital role in maintaining optimal childhood growth, and in ensuring a healthy immune system. Zinc also helps limit inflammation and oxidative stress in our body, which are associated with the onset of chronic cardiovascular diseases and cancers.

Around much of the world, many households eat polished white rice or highly refined wheat or maize flours, which provide energy but do not provide enough essential micronutrients such as zinc. Zinc is an essential part of nearly 3,000 different proteins, and it impacts how these proteins regulate every cell in our body. In the absence of sufficient zinc, our ability to repair everyday wear and tear on our DNA is compromised.

In the randomized, controlled, six-week study the scientists measured the impact of zinc on human metabolism by counting DNA strand breaks. They used the parameter of DNA damage to examine the influence of a moderate amount of zinc on healthy living. This was a novel approach, different from the commonly used method of looking at zinc in the blood or using stunting and morbidity for assessing zinc status.

According to King, these results are relevant to the planning and evaluation of food-based solutions for mitigating the impact of hidden hunger and malnutrition. King believes that biofortification can be a sustainable, long-term solution to zinc deficiency.

For more information please visit: -

https://www.sciencedaily.com/releases/2017/01/170103084620.htm

http://www.prlabs.co.uk/lab-supplies.php?N=zinc-1000ppm-for-icp&Id=60254

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

Fossilized dinosaur brain tissue identified for the first time

An unassuming brown pebble, found more than a decade ago by a fossil hunter in Sussex, has been confirmed as the first example of fossilised brain tissue from a dinosaur.

The fossil, most likely from a species closely related to Iguanodon, displays distinct similarities to the brains of modern-day crocodiles and birds. Meninges - the tough tissues surrounding the actual brain - as well as tiny capillaries and portions of adjacent cortical tissues have been preserved as mineralised 'ghosts'.

The results are reported in a Special Publication of the Geological Society of London, published in tribute to Professor Martin Brasier of the University of Oxford, who died in 2014. Brasier and Dr David Norman from the University of Cambridge co-ordinated the research into this particular fossil during the years prior to Brasier's untimely death in a road traffic accident.

The fossilised brain, found by fossil hunter Jamie Hiscocks near Bexhill in Sussex in 2004, is most likely from a species similar to Iguanodon: a large herbivorous dinosaur that lived during the Early Cretaceous Period, about 133 million years ago.

Triceratops skeleton. Source: Allie_Caulfield Derivative: User:MathKnight [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Finding fossilised soft tissue, especially brain tissue, is very rare, which makes understanding the evolutionary history of such tissue difficult. "The chances of preserving brain tissue are incredibly small, so the discovery of this specimen is astonishing," said co-author Dr Alex Liu of Cambridge's Department of Earth Sciences, who was one of Brasier's PhD students in Oxford at the time that studies of the fossil began.

According to the researchers, the reason this particular piece of brain tissue has been so well-preserved is that the dinosaur's brain was essentially 'pickled' in a highly acidic and low-oxygen body of water - similar to a bog or swamp - shortly after its death. This allowed the soft tissues to become mineralised before they decayed away completely, so that they could be preserved.

"What we think happened is that this particular dinosaur died in or near a body of water, and its head ended up partially buried in the sediment at the bottom," said Norman. "Since the water had little oxygen and was very acidic, the soft tissues of the brain were likely preserved and cast before the rest of its body was buried in the sediment."

Working with colleagues from the University of Western Australia, the researchers used scanning electron microscope (SEM) techniques in order to identify the tough membranes, or meninges, that surrounded the brain itself, as well as strands of collagen and blood vessels. Structures that could represent tissues from the brain cortex (its outer layer of neural tissue), interwoven with delicate capillaries, also appear to be present. The structure of the fossilised brain, and in particular that of the meninges, shows similarities with the brains of modern-day descendants of dinosaurs, namely birds and crocodiles.

In typical reptiles, the brain has the shape of a sausage, surrounded by a dense region of blood vessels and thin-walled vascular chambers (sinuses) that serve as a blood drainage system. The brain itself only takes up about half of the space within the cranial cavity.

In contrast, the tissue in the fossilised brain appears to have been pressed directly against the skull, raising the possibility that some dinosaurs had large brains which filled much more of the cranial cavity. However, the researchers caution against drawing any conclusions about the intelligence of dinosaurs from this particular fossil, and say that it is most likely that during death and burial the head of this dinosaur became overturned, so that as the brain decayed, gravity caused it to collapse and become pressed against the bony roof of the cavity.

"As we can't see the lobes of the brain itself, we can't say for sure how big this dinosaur's brain was," said Norman. "Of course, it's entirely possible that dinosaurs had bigger brains than we give them credit for, but we can't tell from this specimen alone. What's truly remarkable is that conditions were just right in order to allow preservation of the brain tissue - hopefully this is the first of many such discoveries."

"I have always believed I had something special. I noticed there was something odd about the preservation, and soft tissue preservation did go through my mind. Martin realised its potential significance right at the beginning, but it wasn't until years later that its true significance came to be realised," said paper co-author Jamie Hiscocks, the man who discovered the specimen. "In his initial email to me, Martin asked if I'd ever heard of dinosaur brain cells being preserved in the fossil record. I knew exactly what he was getting at. I was amazed to hear this coming from a world renowned expert like him."

The research was funded in part by the Natural Environment Research Council (NERC) and Christ's College, Cambridge.

For more information visit:-

https://www.sciencedaily.com/releases/2016/10/161027175858.htm

http://www.prlabs.co.uk/lab-supplies.php?N=oxygen-mcolortest-titrimetric&Id=26113