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Xanthoproteic Reaction
The xanthoproteic reaction is a method that can be used to detect a presence of protein soluble in a solution, using concentrated nitric acid. The test gives a positive result in amino acids carrying aromatic groups, especially in the presence of tyrosine. If the test is positive the proof is neutralized with an alkali, turning dark yellow. The yellow colour is due to xanthoproteic acid which is formed due to nitration of certain amino acids, most common examples being tyrosine and tryptophan. This chemical reaction is a qualitative test, determining the presence or absence of proteins. Procedure Add 1 ml of concentrated HNO3 to 1 ml of the test sample. Gently heat the mixture and cool it. Slowly add sodium hydroxide (NaOH, in water) solution until the mixture becomes alkaline and a colour change is observed. If the colour changes from yellow to orange, this indicates the presence of an aromatic amino acid. When human skin or nails are exposed to nitric acid, they tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Acid
Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution contains more than 86% , it is referred to as ''fuming nitric acid''. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%. Nitric acid is the primary reagent used for nitration – the addition of a nitro group, typically to an organic molecule. While some resulting nitro compounds are shock- and thermally-sensitive explosives, a few are stable enough to be used in munitions and demolition, while others are still more stable and used as synthetic dyes and medicines (e.g. metronidazole). Nitric acid is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthoproteic Acid
Xanthoproteic acid is a non-crystallizable yellow substance derived from proteins upon treatment with nitric acid. Nitric acid reacts with proteins to form xanthoproteic acid. This reaction is known as the xanthoproteic reaction. This test is carried out by adding concentrated nitric acid to the substance being tested, and then heating the mixture. If proteins are present that contains amino acids with aromatic rings, the mixture turns yellow. Upon adding a strong base, such as ammonia solution (), the color turns orange. These color changes are caused by nitrated aromatic rings in the protein. The xanthoproteic test is specific for aromatic compounds such as tyrosine, tryptophan and phenylalanine. Xanthoproteinic acids are also formed when nitric acid contacts the skin and are a certain giveaway of inadequate care when handling nitric acid. Minor stains are harmless and resolve in a few days. It is a mixture of nitro compound In organic chemistry, nitro compounds are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hooves, and the outer layer of skin in vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong mineralization (biology), unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biology, biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin comes in two types: the primitive, softer forms found in all vertebrates and the harder, derived forms fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nail (anatomy)
A nail is a protective plate characteristically found at the tip of the digit (anatomy), digits (fingers and toes) of all primates, corresponding to the claws in other tetrapod animals. Fingernails and toenails are made of a tough rigid protein called alpha-keratin, a polymer also found in the claws, hooves, and horn (anatomy), horns of vertebrates. Structure The nail consists of the nail plate, the nail matrix and the nail bed below it, and the grooves surrounding it. Parts of the nail The nail matrix is the active Tissue (biology), tissue (or Germ layer, germinal Matrix (biology), matrix) that generates cells. The cells harden as they move outward from the nail root to the nail plate. The nail matrix is also known as the ''matrix unguis'', keratogenous membrane, or onychostroma. It is the part of the nail bed that is beneath the nail and contains nerves, lymph, and blood vessels. The matrix produces cells that become the nail plate. The width and thickness of the nail p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different developmental origin, structure and chemical composition. The adjective cutaneous means "of the skin" (from Latin ''cutis'' 'skin'). In mammals, the skin is an organ of the integumentary system made up of multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments, and internal organs. Skin of a different nature exists in amphibians, reptiles, and birds. Skin (including cutaneous and subcutaneous tissues) plays crucial roles in formation, structure, and function of extraskeletal apparatus such as horns of bovids (e.g., cattle) and rhinos, cervids' antlers, giraffids' ossicones, armadillos' osteoderm, and os penis/ os clitoris. All mammals have some hair on their skin, even marine mammals like whales, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Amino Acid
An aromatic amino acid is an amino acid that includes an aromaticity, aromatic ring. Among the 20 standard amino acids, histidine, phenylalanine, tryptophan, tyrosine, are classified as aromatic. Properties and function Optical properties Aromatic amino acids, excepting histidine, absorb Ultraviolet, ultraviolet light above and beyond 250 nm and will fluorescence, fluoresce under these conditions. This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. Most proteins Absorption spectroscopy, absorb at 280 nm due to the presence of tyrosine and tryptophan. Of the aromatic amino acids, tryptophan has the highest extinction coefficient; its absorption maximum occurs at 280 nm. The absorption maximum of tyrosine occurs at 274 nm. Role in protein structure and function Aromatic amino acids stabilize folded structures of many proteins. Aromatic residues are found predominantly sequestered within the cores o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orange (colour)
Orange is the colour between yellow and red on the spectrum of visible light. The human eyes perceive orange when observing light with a dominant wavelength between roughly 585 and 620 nanometres. In traditional colour theory, it is a secondary colour of pigments, produced by mixing yellow and red. In the RGB colour model, it is a tertiary colour. It is named after the orange (fruit), fruit of the same name. The orange colour of many fruits and vegetables, such as carrots, pumpkins, sweet potatoes, and Orange (fruit), oranges, comes from carotenes, a type of photosynthetic pigment. These pigments convert the light energy that the plants absorb from the Sun into chemical energy for the plants' growth. Similarly, the hues of autumn leaves are from the same pigment after chlorophyll is removed. In Europe and the United States, surveys show that orange is the colour most associated with amusement, the unconventional, extroversion, warmth, fire, energy, activity, danger, taste and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), base and alkali that decomposes lipids and proteins at ambient temperatures and at high concentrations may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the making of wood pulp and paper, tex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', and '' volume concentration''. The concentration can refer to any kind of chemical mixture, but most frequently refers to solutes and solvents in solutions. The molar (amount) concentration has variants, such as normal concentration and osmotic concentration. Dilution is reduction of concentration, e.g. by adding solvent to a solution. The verb to concentrate means to increase concentration, the opposite of dilute. Etymology ''Concentration-'', ''concentratio'', action or an act of coming together at a single place, bringing to a common center, was used in post-classical Latin in 1550 or earlier, similar terms attested in Italian (1589), Spanish (1589), English (1606), French (1632). Qualitative description Often in informal, non- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
