High energy compounds, also known as energy rich compounds, contain high energy bonds that release free energy of -7.3 kcal/mol or greater during hydrolysis. ATP is the most important high energy compound, containing two high energy phosphoanhydride bonds. The hydrolysis of ATP releases -7.3 kcal/mol of free energy and is coupled to endergonic reactions in cells, functioning to link catabolic and anabolic processes through the transfer of its phosphoryl groups. ATP serves as the universal energy currency in living organisms, driving many biological reactions and processes.

1. PRESENTED BY
SUSHMA P.R
1ST M.Sc BIOTECH,
BRINDAVAN COLLEGE
PRESENTED TO
Mrs. DILSHAD BEGUM
BIOCHEMISTRY,
BRINDAVAN COLLEGE

2.  Also known as Energy Rich Compounds
 Compounds in biological system which on
hydrolysis yield free energy equal to or greater
than that of ATP, i.e. ∆ G = -7.3 kcal / mol
 Compounds that yield energy less than -7.3
kcal / mol are called Low Energy Compounds.

3.  Most of the high energy compounds contain phosphate
group [except acetyl CoA] hence they are also called high
energy phosphates.
 The bonds in the high energy compounds which yields
energy upon hydrolysis are called high energy bonds.
 These bonds are notated by the symbol '~‘ [squiggle].
 Fritz Albert Lipmann invented this notation.

4.  The energy that is actually available
[ utilizable ] to do the work is called Free
Energy.
 Change in free energy is denoted by ∆G.
Also known as Gibb’s Free Energy.
 For endergonic reactions ∆G will be +ve
 For exergonic reactions ∆G will be -ve

5.  High energy compounds are mainly classified into 5
groups:
1. Pyrophosphates
2. Enol phosphates
3. Acyl phosphates
4. Thiol phosphates
5. Guanido phosphates or phophagens

6.  The energy bonds in pyrophosphates are acid anhydride
bonds.
 These bonds are formed by the condensation of acid
groups [mainly phosphoric acid] or its derivatives.
 An example for pyrophosphates is ATP. It has two high
energy diphosphate bonds – phosphoanhydride bonds.

7.  The bond present here is enolphosphate bond
 It is formed when phosphate group attaches to a hydroxyl
group which is bounded to a carbon atom having double
bond.
 Example : phosphoenolpyruvate

8.  An example for acyl phosphate is 1,3-
bisphosphoglycerate.
 The high energy bond in this compound is formed by the
reaction between carboxylic acid group and phosphate
group.

9.  Here high energy phosphate bond is absent. Instead high
energy thioester bond is present.
 Thioester bond results from the reaction between thiol and
carboxylic acid group’
 Example : Acetyl CoA

10.  Also known as phophagens
 The bond is known as guanidine phosphates bonds
 It is formed by the attachment of phosphate group to
guanidine group.
 Most important compound with this bond is
phosphocreatine.

11. Class Bond Example (s)
 Pyrophosphates – C – P – P ATP, pyrophosphate
 Acyl phosphates O 1,3-bisphospo-
║ glycerate,carbamoyl
– C – O ~ P phosphate
 Enol phosphates – CH
║
– C – O ~ P PEP

12.  Thiol esters (thioesters) C Acetyl CoA,
║ Acyl CoA
– C – O ~ S –
 Guanido phosphates | phosphocreatine
– N~ P phosphoargenine

13.  Compounds ∆G
o
(kCal/mol)
 Phosphoenol pyruvate - 14.8
 Carbamoyl phosphate - 12.3
 Cyclic AMP - 12.0
 1,3 – Bisphosphoglycerate - 11.8
 Phosphocreatine - 10.3
 Acetyl phosphate - 10.3
 Pyrophosphate - 8.0
 Acetyl CoA - 7.7
 ATP→ADP + Pi - 7.3

14.  ATP is the most important high energy compound in the
living cell.
 It contains an adenine group,a ribose sugar and a
triphosphate.
 ATP is considered as an high energy compound because of
the presence of two phospho anhydride bond.
 Hydrolysis of the terminal phosphate group yields high
negative free energy i.e. -7.3 cal / mol

15.  ATP acts as an link between catabolism [exergonic
reaction] and anabolism [endergonic reaction].
 Catabolic reactions can give energy in the form of ATP.
 Anabolic reactions can utilize energy through hydrolysis
of ATP.
 It transfers phophoryl groups from high energy
compounds to less energetic compounds

17. Adenosine Pi Pi
-7.3kcal
ADP + Pi

18. P P P
Adenosine triphosphate (ATP)
P P P+
Adenosine diphosphate (ADP)
HYDROLYSIS
HIGH ENERGY BOND

19.  The ATP reaction is commonly written as:
ADP + Pi + energy ATP
 The forming of ADP into ATP
 requires energy (endothermic) – -7.3 kcal/mole
RESYNTHESIS OF ATP

20. P P P+
Adenosine diphosphate (ADP)
P P P
Adenosine triphosphate (ATP)
Dehydration
[Remove H2O]

21.  1. ATP – PHOSPHOCREATINE SYSTEM
• ATP is resynthesised via phosphocreatine (PC)
• PC is stored in muscle cell sarcoplasm
• the following reactions takes place :
• PC ---> Pi + C + energy
• energy + ADP + Pi ---> ATP
• the two reactions together are called a coupled reaction
• these reactions are facilitated by the enzyme creatine kinase
• the net effect of these two coupled reactions is :
• PC + ADP ---> ATP + C

22.  2. THE LACTIC ACID SYSTEM
• This system is an anerobic process and takes place in
the sarcoplasm
• The process involves the partial breakdown of glucose
– glucose can only be fully broken down in the
presence of oxygen.
 Only CHO is used in this system
• Total= 2 ATP but this is used for resynthesis of ADP
to ATP not muscualr work
• the end product of this reaction (in the
absence of oxygen) is lactic acid
• the enzyme facilitating the conversion from pyruvic
acid to lactic acid is lactate dehydrogenase (LDH)

23.  THE AEROBIC SYSTEM
 STAGE ONE – GLYCOLYSIS – 2ATP
 this takes place in CYTOPLASM
 and is identical to the lactic acid system
 ATP regenerated = 2ATP per molecule of glucose
 STAGE TWO - KREB’S CYCLE (CITRIC ACID CYCLE) - 2
ATP
 occurs in the presence of oxygen
 taking place in the muscle cell MITOCHONDRIA within the
inner fluid filled matrix
 pyruvic acid (from glycolysis) promoted by enzymes of the
citric acid cycle, or fatty acids (from body fat) facilitated by
the enzyme lipoprotein lipase or protein (keto acids - from
muscle) act as the fuel for this stage

24.  STAGE THREE - ELECTRON TRANSPORT CHAIN –
34 ATP
 occurs in the presence of oxygen
 within the cristae of the muscle cell MITOCHONDRIA
 hydrogen ions and electrons have potential energy which
is released to produce the ATP

25.  The exergonic hydrolysis of ATP is coupled with the
endergonic dehydration process by transferring a
phosphate group to another molecule.
 For example :
ATP + H2O ADP +Pi
glucose + Pi glucose-6-phosphate + H2O
Overall reaction:
glucose+ATP glucose-6-phosphate+ADP

28.  Metabolism
Synthesis
e.g. * Polysaccharides
* Amino acids
* DNA/RNA
 Movement
Muscle contraction
Energy to allow muscle filaments to slide

29.  Active Transport
Changes the shape of carrier proteins
 Secretion
In the formation of the lysosomes necessary for
exocytosis
 Chemical Reactions
A phosphate molecule from ATP can be transferred to
. another molecule
Makes it more reactive
Lowers activation energy

30. WHY ATP IS CONSIDERED AS UNIVERSAL
ENERGY CURRENCY?
 Common intermediate in many reactions
 Links energy requiring and energy producing
reactions
• It is universal with all living things

31.  Easily participates in many reactions
 Drives most biological processes
 One molecule can be synthesised and perform
a large number of jobs