Role of alkaline earth metal ions in biological system

1. ROLE OF ALKALINE EARTH METAL
IONS IN BIOLOGICAL SYSTEM
VARINDER KHEPAR
PhD CHEMISTRY

2. ELEMENTS IN OUR BODY
• Consider the content of the elements in the body of an
average healthy person (weighing 70 kg).
The content of the rest of metals does not exceed one
gram particularly Cu –0.11 g and Mn – 0.02 g

4. DIETARY SOURCE OF CALCIUM
• Calcium is a critical element in
all animals and human beings.
• A healthy human adult has
about 1.05 kg Ca, of which 99%
exists as phosphates resembling
the mineral hydroxyapatite,
Ca10(PO4)6(OH)2 , in bones and
teeth.
• The primary dietary source of
Ca is milk (65-76%), with
smaller amounts derived from
meat, fish and eggs (5-10%),
and still less from non-dairy
foods such as nuts, fruits, beans
etc.

5. CALCIUM
• Ca2+ ions play an important role in biological processes.
• Calcium also plays a significant role in skeletal formation.
• With phosphorus in the mineral hydroxyapatite C5 (PO4)3OH,
it is the major constituent of bones, teeth and shells.
• In addition to skeletal role, Ca2+ plays many biochemical roles
such as:
a) It acts as a messenger for hormonal action
b) It acts as a trigger for muscular contraction
c) It acts as initiation of blood clotting
d) It also plays a role in the stabilization of protein structure
e) It helps in the maintenance of rhythm of heart

6. CALCIUM PUMP
• Ca2+ plays an important role in muscles.
• It triggers a signal that stimulates muscles to contract.
• In the normal state, the concentration in the intracellular
fluids is very low.
• Their concentration in intra cellular fluids is about 10,000
times less than their concentration in the extracellular
fluids.
• The maintenance of low calcium concentration in the intra
cellular fluids is done by biochemical process called as
calcium pump.
• Concentration:
Outside of Cell [Ca2+] = 0.001 M
Inside Cell [Ca2+] = 10-7 M
• Ca2+-ATPase in Cell Membrane controls concentration

7. ROLE OF Ca2+ IN TRANSPORT
• The nerve pulses include the SR(sarcoplasmic
reticulum) membrane quickly release the large
amount of Ca2+ which trigger muscle contraction.
• Therefore, Ca+ ions act as intermediary between
the nerve impulse and muscle contraction.
• Relaxation of the muscle requires that Ca
concentration be reduced to their resting levels.
• This is accompanied by ATP driven Ca2+ transport
protein called Ca+-ATPase.

8. • Just like Na+-K+-ATPase is the integral part of N+-K+
pump, similarly, Ca2+ - ATPase is also an integral
part of Ca2+ pump.
• The phosphorylation by Ca2+ and
dephosphorylation by Mg2+ completes the cycle.
• During the cycle two Ca2+ are transported for
each ATP hydrolysed.
• The very high affinity of At Pase for Ca2+ helps it
to effectively transport Ca2+ from cytosol (where
[Cu2+]<10-5 M) into sarcoplasmic reticulum, SR
(where [Ca2+] about 10-2 M)

9. DEFICIENCY
• In case of excess Ca2+, it comes in to the blood as
ca is rejected by cell and its salts are not soluble.
So excess of calcium leads to the formation of
stones (due to calcium oxalate, rich in tomatoes),
hardening of arteries, and cataracts in the eye.
• The decrease of Ca2+ content in blood due to
dietary deficiency or from an insufficiency of
parathyroid hormone may lead to a disease called
tetany and weakens the bones.

11. MAGNESIUM
• Magnesium, an abundant element in the earth’s crust, is
vital to both plant and animal life.
• Chlorophyll pigment in plants is a Mg-porphyrin complex
• All enzymatic reaction in animals that are catalyzed by
ATP (Adenosine Triphosphate) require Mg as a cofactor.
• Oxidative phosphorylation, DNA transcription, RNA
function, protein synthesis and critical cell membrane
functions are all dependent upon optimal Mg
concentrations.
• An average human being holds about 35g of Mg, of
which approximately 99% is either intracellular or it is
present in bones.

12. DIETARY SOURCES OF Mg
• High Mg Dietary
sources include green
leaves, nuts, sea foods
and vegetables.
• Meat has intermediate
Mg content.
• Deficiency of Mg
causes convulsions and
excess causes
anaesthetic feeling.

13. BIOLOGICAL ROLE OF Mg2+
• Mg2+ is the fourth-most-abundant metal ion in
cells
• Chlorophyll
• In photosynthetic organisms, Mg2+ has the
additional vital role of being the coordinating
ion in the chlorophyll molecule.
• This role was discovered by Richard Willstätter,
who received the Nobel Prize in Chemistry 1915
for the purification and structure of chlorophyll
binding with six number of carbon.

14. • Enzymes
• Mg2+ interacts with substrates, enzymes as
part of the active site.
• Mg2+ interacts with substrates through inner
sphere coordination, stabilises the anions or
reactive intermediates, and bind to ATP and
activate the molecule to nucleophilic attack.
• ATP (adenosine triphosphate), the main
source of energy in cells, must be bound to a
magnesium ion in order to be biologically
active.

15. • Nucleic acids
• Nucleic acids have an important range of
interactions with Mg2+
• The binding of Mg2+ to DNA and RNA stabilises
structure
• Ribosomes contain large amounts of Mg2+ and
provide the stabilisation to the complex of
ribo-protein

16. BARIUM
• Barium has no biological role.
• The British Pharmaceutical Codex from 1907
indicates that barium chloride ["barii
chloridum", BaCl2. 2H2O] has a stimulant
action on the heart and other muscles.
• Barium sulphide (BaS) was used as a
depilatory agent (removes hair).

17. • Barium enema: Barium is a white, ‘radio-opaque’
powder that is visible with x-rays. It is used to
demonstrate the structure and the function of
the organs that make up the digestive tract, such
as the stomach, small bowel and large bowel. A
liquid that contains barium (a silver-white
metallic compound) is put into the rectum. The
barium coats the large bowel and X-rays are
taken. This test may show what part of the bowel
is blocked.

18. • BARIUM MEAL
You will be asked to drink the barium so the radiologist
can observe your swallowing and evaluate the
structure of your oesophagus. During a barium meal
you will be asked to drink a mixture that is fizzy, or two
substances. These drinks contain ingredients that cause
gas to be produced, which expands your stomach and
the duodenum. When the gas is combined with the
barium it creates a coating on the inside of your
stomach and allows the radiologist to evaluate the
stomach lining. Many people feel the urge to burp
during this part of the examination.

19. BERYLLIUM
• Beryllium has no known biological role, and its
dust causes chronic inflammation of the lungs
and shortage of breath.
• Brief exposure to a lot of beryllium, or long
exposure to a little, will bring lung condition
which is known as berylliosis.

20. STRONTIUM
• In biological systems, calcium is substituted to
a small extent by strontium.
• In the human body, most of the absorbed
strontium is deposited in the bones. The ratio
of strontium to calcium in human bones is
between 1:1000 and 1:2000, roughly in the
same range as in the blood serum.
• The average human has an intake of about
two milligrams of strontium a day

21. • But strontium ranelate also increases the risk
of serious cardiovascular disorders
• Strontium has been shown to inhibit sensory
irritation when applied topically to the skin
• Those with a personal or family history of
blood clotting disorders are advised to avoid
strontium

22. RADIUM
• Radium has no known biological role. It is toxic due to its
radioactivity.
• Radium is present in all uranium ores, and could be
extracted as a by-product of uranium refining.
• Radium-223 is sometimes used to treat prostate cancer
that has spread to the bones. Because bones contain
calcium and radium is in the same group as calcium, it can
be used to target cancerous bone cells. It gives off alpha
particles that can kill the cancerous cells.
• Radium used to be used in luminous paints, for example in
clock and watch dials. Although the alpha rays could not
pass through the glass or metal of the watch casing, it is
now considered to be too hazardous to be used in this way.

23. COLOUR ON FLAME

24. REFRENCES
• https://epathshala.nic.in
• https://en.wikipedia.org/wiki/Calcium_in_biol
ogy
• https://en.wikipedia.org/wiki/Magnesium_in_
biology
• Jauhar S P (2016) Inorganic chemistry. Modern
publishers, Pp 146-82.
• https://courses.lumenlearning.com