The ATP CYCLE and Cell Bioenergetic

Transkripsi

1 The ATP CYCLE and Cell Bioenergetic The chemical basis for the large freeenergy changes that accompany hydrolysis of ATP and other high-energy phosphate compounds

2 ATP adl bentuk energi yang menghubungkan proses katabolisme dan anabolisme Sel heterotrop memperoleh energi bebas dari katabolisme nutrisi dan menggunakannya untuk membuat ATP dari ADP dan Pi

3 ATP: the energy currency that links catabolism and anabolism. H 2 O CO 2 ATP *ATP, ADP, dan P terdapat di dalam semua sel hidup *Berperan sebagai pemindah energi Catabolism O 2 Fuels ADP + Pi 1. Biosynthesis 2. Contraction and motility 3. Active transport 4. Transfer of genetic information

4 Gibbs free energy, G expresses the amount of energy capable of doing work during a reaction at constant temperature and pressure. When a reaction proceeds with the release of free energy (that is, when the system changes so as to possess less free energy), the free-energy change, G, has a negative value and the reaction is said to be exergonic. In endergonic reactions, the system gains free energy and G is positive.

5 Hidrolisis ATP menghasilkan energi bebas yang besar dan negatif (ΔG kj/mol); Yaitu ketika ATP dihidrolisis menjadi adenosine diphosphate (ADP) dan orthophosphate (Pi); Atau dihidrolisis menjadi adenosine monophosphate (AMP) dan pyrophosphate (PPi).

6 Structures of ATP, ADP, and AMP. These adenylates consist of adenine (blue), a ribose (black), and a tri-, di-, or monophosphate unit (red). The innermost phosphorus atom of ATP is designated Pα, the middle one Pβ, and the outermost one Pγ

7 Energi bebas yang tinggi juga dihasilkan dari hidrolisis senyawa terfosforilasi dan thioester High Phosphoryl Transfer Potential Compounds. These compounds have a higher phosphoryl transfer potential than that of ATP and can be used to phosphorylate ADP to form ATP

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11 The phosphate compounds found in living organisms can be divided into two groups Based on their standard free energies of hydrolysis: High-energy compounds have a ΔG of hydrolysis more negative than 25 kj/mol; low-energy compounds have a less negative G. Based on this criterion, ATP, with a ΔG of hydrolysis of 30.5 kj/mol (7.3 kcal/mol), is a high-energy compound; glucose 6-phosphate, with a Δ G of hydrolysis of 13.8 kj/mol (3.3 kcal/mol), is a low-energy compound.

12 FIGURE 13 9 Ranking of biological phosphate The flow of phosphoryl groups, represented by P, from highenergy phosphoryl donors via ATP to acceptor molecules (such as glucose and glycerol) to form their lowenergy phosphate derivatives.

13 Ranking of biological phosphate compounds by standard free energies of hydrolysis. The flow of phosphoryl groups, represented by P, from high-energy phosphoryl donors via ATP to acceptor molecules (such as glucose and glycerol) to form their low-energy phosphate derivatives. This flow of phosphoryl groups, catalyzed by enzymes called kinases, proceeds with an overall loss of free energy under intracellular conditions. Hydrolysis of low energy phosphate compounds releases Pi, which has an even lower phosphoryl group transfer potential.

14 ATP Provides Energy by Group Transfers, Not by Simple Hydrolysis FIGURE 13 8 ATP hydrolysis in two steps. (a) The contribution of ATP to a reaction is often shown as a single step, but is almost always a twostep process. (b)shown here is the reaction catalyzed by ATPdependent glutamine synthetase. (1) A phosphoryl group is transferred from ATP to glutamate, then (2) the phosphoryl group is displaced by NH3 and released as Pi.

15 Fosfat berenergi tinggi dihasilkan dari pemecahan glukosa menjadi laktat 2 donor gugus P ke ADP: a. 3-phosphoglyceroyl phosphate b. phosphoenol pyruvate Ke-2 senyawa tsb dihasilkan dari degradasi glukosa menjadi laktat (proses GLIKOLISIS)

16 Glukosa 3-phosphoglyceroyl phosphate ATP Phosphoenol pyruvate ATP Laktat