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Chapter 4-1. ATP Synthase

Higher category: 【Biology】 Chapter 4. Cell and Energy Metabolism 

1. ATP synthase

2. Mechanism for ATP synthase

1. ATP synthase: F₀F₁ complex

⑴ F₀ complex: Distributed in the inner membrane of mitochondria and slightly extruding into the substrate.

⑵ F₁ complex: Involved in chemical osmotic phosphorylation as it is located in the substrate and contains ATP synthase.

⑶ CF₀CF₁ complex is observed during ATP synthase in photosynthesis, but is almost similar to F₀F₁ complex.

Figure 1. The structure of CF₀CF₁ complex

2. Mechanism for ATP synthase

⑴ 1^st. A circular plate divided by 3 parts (loose site, tight site, open site) by 120 degree and there is an asymmetric protein on the center of the circular plate. 

⑵ 2^nd. On loose site adhere ADP and P_i.

⑶ 3^rd. When a single H⁺ enters, the asymmetric protein rotates 120°, creating the effect of a 120° rotation of the site.

① Aspartic acid(negative charge amino acid) in ATP synthase holds proton.

② If ATP is added, ATP synthase rotates counter clockwise; if ATP is synthesized, ATP synthase rotates clockwise.

⑷ 4^th. If 2 substrates come into tight site, one is strongly tied to another producing ATP.

⑸ 5^th. If one H⁺ enters again, the asymmetric protein rotates 120° again.

⑹ 6^th. Coming into open site → ATP release

⑺ 7^th. In this mechanism, 3 H⁺ make 1 ATP. 

⑻ 8^th. Calculation of yield

① NADH yield = Total number of moving H⁺ ÷ (4 H⁺ / 1 ATP) = (4 × 2 + 2) ÷ 4 = 2.5

② FADH₂ yield = Total number of moving H⁺ ÷ (4 H⁺ / 1 ATP) = (4 × 1 + 2) ÷ 4 = 1.5

Input: 2019.03.14 13:33