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| Research Substance ISBN: 978-93-93166-22-7 For verification of this chapter, please visit on http://www.socialresearchfoundation.com/books.php#8 |
Biological Role of Trace Elements in Living System |
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Swarn Lata Bansal
Research Fellow
Chemistry
D.A.V. P.G. College
Kanpur Uttar Pradesh, India
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DOI: Chapter ID: 16221 |
| This is an open-access book section/chapter distributed under the terms of the Creative Commons Attribution 4.0 International, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
Trace elements are present in different forms in the
nature and are essential for body to perform different function. These are
important for cell functions at biological chemical and molecular steps. These
elements show many biochemical reactions by acting as cofactors for many
enzymes as well as centres for stabilising structures of enzymes and proteins.
These elements control important biological steps by binding to molecules on
the receptor site of cell membrane to prevent entry of specific molecules in to
the cell. They are responsible for the stability of important biological
molecules. Human body contains essentially complex organic molecules
and also certain metal ions, complex organic molecules are proteins, peptides,
enzymes and lipids. There are also definite evidences of at least 40 elements
in human and animal body. Possibility of existence of some more elements in
living system cannot be ruled out. Out of these at least 29 elements are
essential for healthy human life, of these 29 elements, 13 elements are non
metals (H, C, O, N, S, P,Cl, F, Br, I, B, S, As) and 16 elements are metals(Na, K, Ca, Mg, F,
Cu, Zn, Co, Ni, Mn, Al, Pb, Sn, Mo, V & Ti) out of the 13 non-metals , C,H,O,N
are found in little amount in every tissue structure, synthesis and formation
of various biochemical substances within these structures. These elements are
derived in the body from carbohydrates, lipids and proteins. Rest of the
elements have been classified into essential and non-essential elements. Essential elements are absolutely necessary and the
deficiency may cause undesirable consequences. They have been further
classified in to (a) macro-essential elements (Ca, Mg, K, Fe, P, S, Cl) and (b)
micro essential elements (Cu, Mn, Co, Zn, Mo,F, ). Macro
Essential Elements The
macro-essential elements—Na, Mg, K, Ca, Cl, and P—are found in large amounts in
biological tissues and are present as inorganic compounds, either dissolved or
precipitated. Calcium:The most
abundant metal in body. Its main quantitative use being the stabilization of
the endoskeleton.It is found in bones as apatite 94% of Ca3(PO4)2
and 6%in teeth, skin, blood , muscles and nerves. It builds bones assistants in
clotting of blood, prevents certain nerve diseases.These are required to
trigger the contraction of muscles and to maintain the regular beating of the
heart. Magnesium: It is
present in animal cells. It assists in forming bones and it is necessary for
nerve impulse transitions. In plant Mg ++ ions are present in
chlorophyll which is the green colouring matter present in plants chlorophyll absorbs light from the sun and
carries the process of photosynthesis. Mg++ ions form complex with
ATP, and are constituents of phosphohydrolases and phosphotransferases, which
are enzymes for reactions involving ATP and energy release. They are also
essential for the transmission of impulse along nerve fibres. Potassium: It is found
in blood, plasma, cells, muscles and nerves. It maintains the sensitivity of
nerves, control the muscles and help to control the heart action. They have intracellular ion for all
types of cells and its complement sodium in providing electrolyte balance. It is
important in neurotransmission, muscle contraction and heart function.
Deficiency increases risk of hypertension, stroke and cardiovascular disease. Sodium: It is
found in extra cellular fluids and forms 93% of the total cation present in the
blood. It involves in acid base balance in the body it helps in many enzyme
reactions. It is charge carrier, help to maintain osmotic pressure on either
side of cell wall, also help in maintain of sensitivity of nerves and control of
muscles. Iron:It is
essential in small amounts for both plant and animal life. Iron is the main
constituent of blood. It is found in the form of iron complex known as
haemoglobin in blood. In the blood haemoglobin acts as oxygen carrier from
lungs to the tissues as a number of other enzymes: aldehyde oxidase (oxidation
of aldehydes), catalases and peroxidise (decomposition of H2O2)
and succinic dehydrogenase (the aerobic oxidation of carbohydrates). Phosphorous: It is
present in every cell of body in inorganic as well as organic form. It is
estimated that body contains 70 gm phosphorus, 90% in bones and teeth, 8% in
muscles, 2% in blood and brain. It plays an important role in energy retention
and transfer processes. Sulphur: It is a component of
the amino acids cysteine and methionine. Sulphur deficiency causes physical
deformities and mental retardation and can be fatal. It is found in body in
the form of organic molecules such as cystein, heparin, insulin, thiamine etc.,
in the cartilage, bone matrix, blood, keratin and other tissues. Chlorine: It is
present in blood, plasma, cells, muscles, and cerebrospinal fluid. It is taken
in the form of salt (sodium chloride) its level in body is related to hat of
sodium in the body it assists in digestion. Chlorine combined
with sodium forms common salt which is important for electrolyte balance in the
body. As a constituent in hydrochloric acid, it is important for digestion. Micro
Essential Elements Copper: It is an
essential constituent of several enzymes such as cytochrome oxidase, monoamine
oxidase, catalase, peroxidase, ascorbic acid oxidase, lactase, tyrosinase, and
superoxide dismutase (SOD). Human body contains to 100- 150 mg of copper in
muscles, in bones, in liver and rest in serum. Serum copper is found in two
forms, namely, direct reacting copper which is loosely bound to albumin
fraction of the serum ceruloplasmine, copper helps in the biosynthesis of
haemoglobin and transport of iron Zinc: It is an essential trace element that
functions as a cofactor for certain enzymes involved in metabolism and cell
growth. It involved in the metabolism of proteins, carbohydrates, lipids, and
energy. They have vital for the healthy working of many of the body’s systems;
it acts as an essential role in numerous biochemical pathways. Zinc
metalloenzymes catalyse peptide hydrolysis and maintain HCo3/Co2
equilibrium. Cobalt: It is an essential trace element for the human
body, where it is a key constituent of cobalamin (the scientific name of
vitamin B12). It also has a crucial role in the formation of amino acids and
neurotransmitters. It is integral part of vitamine B12 which affects
the formation of blood. Inorganic forms
of cobalt are toxic to the human body, and the longer they stay in the body
human body more the detrimental effects they cause in cells. Manganese: It is a
trace mineral that is present in tiny amounts in our body. Mn helps the body to
form connective tissue, bones, and blood-clotting factors. It also plays a role
in fat and carbohydrate metabolism, calcium absorption, and blood sugar
regulation our body contains about 10 mg of manganese mainly present in kidney
and liver tissues and blood, it catalyses several enzymes, helps in biological
oxidations in the mitochondria, helps in synthesis of long chain fatty acids
etc. Molybdenum: it is
mostly present in liver and kidney. Some of the fluroproteins contain traces of
molybdenum where it is believed to help in the electron transport. Fluorine:Fluorides
exist in our body in the bones and the teeth. If concentration of fluoride is
less than 1.5 ppm of water It preserves the bones and teeth in healthy
condition. An excess fluoride causes many types of disease in bones and teeth. It is used by few micro-organisms and
plants but is not essential for animals. However, fluorine does strengthen
teeth and a deficiency can be a cause of dental decay. Iodine: It is
carried around the body as iodide. It is absorbed in thyroid gland and is
oxidise to iodine and combine with tyrosine which is converted in to hormones
thyroxin. Deficiency of iodine in the body causes a disease known s goitre. NON –
ESSENTIAL ELEMENTS The elements (Br, B, Si, As, Ni, Al, Pb, Sn, V and Ti)
are present in very small amount. No definite function of these elements is
known in the body. No deficiency disease pertaining to these elements is known;
hence it is difficult to say at present whether these elements are required at
all by human body. Some of these elements have been found to be toxic. As and
Pb are well known toxic elements. Toxicity of
Metals Metals are natural constituents of earth s crust and they
are present in soil, water and living matter. Many metals are essential to
sustain life system. Same heavy metals ate key compound of modern
civilisation which are immutable i.e.
once a metal is mobilised in environmental its total amount remain the same,
regardless of form it may change. Heavy metals in the atmosphere come from a
wide variety of natural and manmade sources. There are about 18 elements in
periodic classification of these approximately 86 are metals, fortunately out
of these only 18 metals are toxic. Thus we have divided toxic metals according
to their group since there is some resemblance in toxicity of similar metals.
We have group II: Be, Zn, Cd, Mg, group
III: Tl, group IV: Pb, group V: V, As, Z, Sb, group VI: Cr, U, Se, Te, group
VII: Mn, group VIII: Co, Ni, Ca and Pt. Beryllium Beryllium is another rare light element
that has little function for life. Beryllium deficiency can cause weight loss
and fatigue It has a very short half-life but its energy levels are tuned along
with those of carbon-12 to allow synthesis through nuclear fusion of helium to
form carbon-12. Chromium: It is an essential trace element that can improve insulin
sensitivity and enhance protein, carbohydrates and lipid metabolism. It may
enhance muscle mass, weight loss and glucose control. It produces significant
increases in enzyme activity and serves an important function in carbohydrate
metabolism, stimulation of fatty acid and cholesterol synthesis from acetate in
the liver. They may include impaired glucose tolerance, leading to reduced
control of blood sugar in people. Selenium: Se is a
vital trace element for human body health, where it is found at the active site
of a wide range of selenoproteins as selenocysteine. It is an important
component of the antioxidant enzymes such as glutathione peroxides and
thioredoxin reductase. Lead: It is a
relatively un-reactive metal and has a weak metallic character with amphoteric
nature, where lead and its oxides react with both acids and bases. Pb has
several useful mechanical properties to use it in industrial applications
including high density, low melting point, ductility, and resistance to
corrosion. Cadmium:
It is a non-essential heavy metal to plants, can occur in soil at high
concentrations, thus becoming toxic to all organisms. It is number of several
sources including employment in primary metal industries, eating contaminated
food, smoking cigarettes.its little amount present in certain foods such as
leafy vegetables, potatoes, grains and seeds liver and kidney of animal. It is similar
Hg (II), Cd (II) also binds strongly with the –SH groups of Cysteine residues
of enzymes e.g., Carbonic anhydrase, dipeptidase, carboxy peptidase etc. These
ions effect the active confirmation of bio- molecules due to the strong
binding. Mercury
: It is a most toxic metal in the
environment and Sources of Mercury pollution are industrial waste, mining
(as mercury is trace component of many minerals), pesticides, coal &lignite
(containing about 100 ppb of Hg). It exists in three forms: organic (eg. methyl
mercury in fish), inorganic (eg. Batteries
& disinfectants) and elemental (eg. Dental amalgam and thermometers). All
types of mercury accumulate in the body over time. They have harmful effects on
nervous, digestive and immune systems, lungs, kidneys, brain, heart and eyes. It
toxicity is based on the strong affinity for the deprotonated forms of thiol
ligands such as Cysteine; therefore, thiols, RSH, with sulfahydryl group, -SH
are also called mercaptans (Mercurium captans). Trace elements also act as essential structural components of biological
molecules. In many systems where trace elements do not change oxidation states
or otherwise participates directly in biochemical reactions. They have
important biological effects because of their participation in an amplification
mechanism. Macro elements are present in larger amounts and play structural
roles whose distribution in cells in tightly controlled. These ions are
selectively transported across cell membranes by ion pumps. Other trace
elements catalyse group transfer reactions, while others ye are essential
structural components of biological molecules. References: |