High energy compounds

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

 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.

 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.

 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

 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

 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.

 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

 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.

 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

 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.

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

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

 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

 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

 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

Adenosine Pi Pi
-7.3kcal
ADP + Pi

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

 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

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

 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

 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)

 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

 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

 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

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

 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

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

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

High energy compounds

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