Essential fifth element

Coenzyme B12 is the cofactor form of vitamin B 2, which is unique among all the vitamins in that it contains not only a complex organic molecule but an essential trace element, cobalt. The complex corrin ring system of vitamin B12 (colored blue in Fig. 2), to which cobalt (as Co3+) is coordinated, is chemically related to the porphyrin ring system of heme and heme proteins (see Fig. 5-1). A fifth coordination position of cobalt is filled by dimethylbenzimidazole ribonucleotide (shaded yellow), bound covalently by its 3 -phosphate group to a side chain of the corrin ring, through aminoisopropanol. 

Well then, my dear listeners, let us proceed with fervor to another problem Having sufficiently analyzed in this manner the four resources of science and nature, which we are about to leave [ie. fire, water, air, and earth) we must consider a fifth element which can almost be considered the most essential part of chemistry itself, which chemists boastfully, no doubt with reason, prefer above all others, and because of which they triumphantly celebrate, and to which they attribute above all others the marvellous effects of their science. And this they call the solvent (menstruum). Even if the once famous scholar J. B. Van Helmont (1577-1644) claimed to have prepared this Alkahest in a phial, together with the adherents of the alkahest theory he was ridiculed by his contemporaries who asked in which vessel he has stored this universal solvent. 

Meanwhile, Paracelsus (1493-1541) worked on distillation to separate the essential from the non-essential parts of a compound, and developed further the quinta essentia (quintessence) theory of a fifth element, involved in imbuing life. His radical ideas greatly influenced medicine during the Renaissance. According to Paracelsus, God makes... 

Figure 1.14 is a simple schematic representation of the various distillation processes. Materials obtained in this way are referred to as essential oils. Thus, for example, the oil obtained by steam distillation of lavender is known as the essential oil of lavender or lavender oil. The term essential oil arises from the Aristotelian theory that matter is continuous and composed of four elements, viz. fire, air, earth and water. The fifth element, or quintessence, was considered to be spirit. Distillation was believed to separate the spirit of the plant from its physical matter hence the terms spirits or essential (short for quintessential) oils were applied to distillates. Occasionally, the monoterpene hydrocarbons... 

One of the ideas that arose in the early phase of European alchemy was that all substances were composed not only of the four terrestrial elements but also of a fifth, which Aristotle had maintained was confined to the heavens. This fifth element was known as the quintessence of the substance in which it occurred. The marvellous properties of alcohol led to the belief that it was the quintessence of wine. Furthermore, alcohol was the first organic solvent known, and could extract essential oils fi om plants. These, with their distinctive odours, seemed to be the quintessences of the plants. Thus the quintessences of herbs and other plants could be extracted by solution or distillation with alcohol to form a liqueur. The earliest liqueurs were prepared for their medicinal properties only later was their use appreciated in a purely social context. 

Volatile oils comprise all the substances which pass through steam distillation process. The origin of volatile oil is traditional of German work Aetherischen Oele in the first time described by GUdemeister and Hoffmann in 1899 [1]. It is the Quinta essentia (quintessence) which represents the efficient part of every dmg. The current name essential oil recalls the Paracelsian concept [2], The quintessential oil originates fi om the Aristotelian idea that matter is composed of four elements, namely, fire, air, earth, and water. The fifth element, or quintessence, was then considered to be spirit or life force [3]. The term essential oils is also used for volatile oils. 

Calcium is a metallic element, fifth in abundance in the earth s crust, of which if forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium. 

Hie fifth-row transition elements have general similarity to the fourth-row transition elements. The electron structure is essentially the same except that the 4d orbitals are filling instead of the 3d orbitals. Near the beginning of the sixth-row transition elements there is a change the/ orbitals begin to fill to form fourteen elements before the d orbitals can be occupied to give the typical transition elements. This chapter will dis-... 

The tertiary structure of small subunit enzymes can be subdivided into four distinct regions, and the C-terminal or flavodoxin domain of the large subunit enzymes becomes a fifth region. These are indicated in Fig. 8 for clarity. The first region is the amino terminal arm (Fig. 8), which extends 50 or more residues from the amino terminus almost to the essential histidine residue (to residue 53 in PMC, 60 in PVC, 73 in BLC, and 127 in HPII). There is very little structural similarity in the N-terminal region and, in the case of HPII, the structure of the terminal 27 residues is not even defined and they do not appear in the crystal structure. Within the N-terminal arm is a 20-residue helix, helix a2 in HPII, which is the first secondary structure element common to all catalases. The presence of helix al varies among catalases, and there is no sequence or location equivalence even when it is present. 

Nitrogen occurs in nature where it constitute nearly three fifth of the earth s atmosphere. It also occurs in the combined form as nitrates. Nitrogen is an essential element for living matter because it is an important constituent of proteins and even human body. Phosphorus is also essential for life because its compound control almost all biological processes. 

Phosphorus is a vital element in the composition of all living matter and there is no known organism in which the chemistry of the element is not utilised. The human body contains many thousands of different phosphorus compounds, almost all of which are essential for its proper function. It contains very roughly 1% by weight of the element, about four fifths of this being present as hydroxyapatite in bones and teeth. Phosphorus constitutes about 0.3% of the total weight of the brain, about 0.2%... 

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