High energy compounds

. 1. Pyrophosphates
2. Enol phosphates
3. Acyl phosphates
4. Thiol phosphates
5. Guanido phosphates or phophagens

1. HIGH ENERGY COMPOUNDS AND ATP AS UNIVERSAL ENERGY CURRENCY PRESENTED BY SUSHMA P.R 1 ST 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. HIGH 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 WHAT IS FREE ENERGY ?

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 CLASSIFICATION OF HIGH ENERGY COMPOUNDS

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. PYROPHOSPHATES

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 ENOL PHOSPHATES

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. ACYL PHOSPHATES

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 THIOL PHOSPHATE

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. GUANIDO PHOSPHATES

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 TYPES OF HIGH ENERGY COMPOUNDS

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 HIGH ENERGY COMPONDS AND FREE ENERGY RELEASED

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 ATP AS UNIVERSAL ENERGY CURRENCY

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

16. HYDROLYSIS OF ATP Adenosine Pi Pi -7.3kcal Hydrolysis ADP + Pi

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

18. 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

19. P P P + Adenosine diphosphate (ADP) P P P Adenosine triphosphate (ATP) Dehydration [Remove H 2 O]

20. 1. ATP – PHOSPHOCREATINE SYSTEM ATP is resynthesised via phosphocreatine (PC) PC is stored in muscle cell sarcoplasm the following reactions takes place : PC ---> P i + C + energy energy + ADP + P i ---> 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 3 PATHWAYS FOR ATP RESYNTHESIS

21. 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)

22. 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

23. 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

24. The exergonic hydrolysis of ATP is coupled with the endergonic dehydration process by transferring a phosphate group to another molecule. For example : ATP + H 2 O ADP +Pi glucose + Pi glucose-6-phosphate + H 2 O Overall reaction: glucose+ATP glucose-6-phosphate+ADP COUPLED REACTION - ATP

25. ATP AS A LINK BETWEEN CATABOLIC AND ANABOLIC PATHWAYS

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

27. 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

28. 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 IN SUMMARY

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

30. THANK YOU