Hexokinase binds to ATP, the structural composition of ATP synthase

ATP synthase is mainly composed of F (a water-soluble part that extends outside the membrane) and FO (embedded in the membrane). The subunits and numbers of ATP synthase vary from species to species**. Taking bovine heart mitochondrial ATP synthase as an example, its F contains only 3, 3, , a total of 9 subunits, FO contains A, B2, C10, a total of 13 subunits, F and FO are linked by OSCP stalks, and there are inhibitory proteins.

In the process of synthesizing hydrolyzed ATP, the "rotor" rotates 100 times per minute under the impetus of the hydrogen ion flow through the FO, and interacts with the three subunits in turn to regulate the conformational change of the catalytic sites of the subunits. The "stator" connects 3, 3 with FO on one side.

ATP synthase is facing problems:

1. How to achieve efficient mechanical-chemical coupling between the chemical cycle on the "stator" and the step-by-step rotation of the "rotor".

2. The sequential reversible conformational transformation of the three catalytic sites: o l, l t and t o, and the close interaction relationship.

3. All three catalytic sites bind to nucleosides to promote the motor to rotate, or only two of them need to be combined.

4. Whether the binding and debinding of ADP and R to the catalytic site are sequential or random.

F1: Water-soluble globulin, protruding from the inner membrane in the matrix, composed of 9 subunits such as δ and 1, according to the resolution of X-ray crystal diffraction analysis, the 3 and 3 subunits are alternately arranged in an orange petal-like structure, and each subunit has enzymatic activity when binding. and subunits have nucleotide binding sites, and the binding sites of the subunits have catalytic activity for ATP synthesis or hydrolysis.

Animal mitochondrial F1 also has an inhibitor protein, which specifically inhibits the activity of F1-ATPase, which may deregulate the function of enzyme activity, but cannot inhibit ATP synthesis. It has a strong affinity with the subunit and combines to form a totor. Located at 3, 3, co-rotation to regulate the opening and closing of the three subunit catalytic sites.

The subunit has the function of inhibiting ATP hydrolase activity, and at the same time has the function of blocking hydrogen ion channels and reducing hydrogen ion leakage.

FO: A hydrophobic protein complex chimeric on the inner membrane, forming a transmembrane proton channel. Its type varies greatly in different species, in bacteria FO is composed of three subunits: A, B, C, ; In chloroplasts, there are four subunits; FO within mitochondria is more complex.

Electron microscopy showed that the multiple copies of the C subunit formed a ring-like structure, the dimers of the A and B subunits were arranged on the outer ring of the 12-mer C subunit, and the A, B and δ subunits together formed a "stator". One of the subunits in FO can be combined with oligomycin (which is also the ** of FO in O, many people mistakenly think it is 0, but it is actually a misreading), through which the flow of hydrogen ions through FO can be regulated, and when the proton dynamics are very small, it can prevent ATP hydrolysis; It can also play a role in protecting and resisting changes in the external environment.

Popular Science China Science Encyclopedia: ATP synthase.

ATP synthase: ATPase catalyzes the synthesis of the energy substance ATP in the cell.

The enzyme is inhibited by high concentrations of ATP, which will remove the binding curve of the enzyme to the substrate fructose-6-phosphateHyperbolaThe deformation becomes an S shape, andCitric acidIt is to inhibit the activity of phosphofructokinase by enhancing the inhibitory effect code of ATP, thereby slowing down the glycolysis process.

Phosphofructokinase, also known as 6-phosphofructokinase-1, is a class of kinases that can act on fructose-6-phosphate and neutralize hexokinase and pyruvate in glycolysis.

Kinases catalyze irreversible reactions, so all three enzymes regulate the glycolytic pathway.

fructose 2,6-bisphosphate is its strongest allosteric activator.

Glycolysis precautions.

1 molecule of PGAL is generated from 1 molecule of pyruvate under the action of enzymes. In this process, an oxidation reaction occurs to generate one molecule of NADH, and two substrate-level phosphoric acid limbs occur to generate two molecules of ATP. In this way, a glucose.

In the second stage of glycolysis, the molecule generates a total of 4 ATP, 2 NADH and 2 H+, and the product is 2 pyruvate.

In the first stage of glycolysis, 2 ATPs are consumed in the activation of 1 glucose molecule. Therefore, in the process of glycolysis, while 1 glucose produces 2 molecules of pyruvate, 2 molecules of ATP and 2 molecules of Nadh and H+ are obtained later, and Nadh and H+ enter the mitochondria through different shuttle pathways.

Participate in the respiratory chain.

Produces different amounts of ATP.

This is high school biology common sense, ATP is required for the synthesis of enzymes.

Reason: The essence of enzymes is protein or RNA, and the synthesis of enzymes that are essential for RNA is through RNA polymerase, and ATP is needed for this life activity.

2.Enzymes of proteins not only need energy for DNA transcription and translation, but also need ribosomes, endoplasmic reticulum, and Golgi apparatus for processing, and these are all life activities, and life activities need energy, and most of these energy comes directly from ATP.

3.The law of conservation of energy shows that energy is required for the synthesis of enzymes, and most of the energy required by organisms is provided by ATP.

4.All organelles of normal cells need to consume ATP because they all need to carry out vital activities, which in turn require energy.

5.Most of the enzymes are proteins, and the process of protein synthesis, gene transcription, tRNA transport, amino acids, translation, processing, etc., all involve energy consumption.

1 Pinyin 2 Annotations.

atp hé méi

ATP synthase is widely found in old mitochondria, chloroplasts, prokaryotic algae, heterotrophic bacteria and photosynthetic bacteria, and is a key enzyme for energy metabolism in living organisms. The enzyme is located on the thylakoid membrane, plasma membrane or inner mitochondrial membrane, respectively, and participates in oxidative phosphorylation and photosynthetic phosphorylation reactions, and catalyzes the energy "currency" of synthetic organisms under the impetus of the transmembrane proton kinetic potential - the F0 part of synthase is nearly half smaller than the diameter of the kinetic structure of flagella. The movement of flagella goes through hundreds of steps, whereas the movement of ATP synthase requires only a few steps.

ATP synthase with different ** basically has the same subunit composition and structure, consisting of two parts: F1 protruding outside the membrane and F0 embedded in the membrane (called CF1 and CF0 respectively in chloroplasts). The F1 part is composed of 5 subunits, namely , , and subunits of animal mitochondria F1, as well as oligomycin-sensitive protein (OSCP) subunits and inhibitors. F1 has 6 nucleotide binding sites, 3 of which are catalytic sites, catalyzing the synthesis or hydrolysis of ATP.

F0 is chimeric on the membrane and is a hydrophobic protein complex that forms a transmembrane proton channel. In bacteria, F0 is composed of 3 subunits, A, B, and C, and in blue-green algae, A, B, and B'and C subunits, which correspond to , and 4 subunits in chloroplasts, and the F0 of mitochondrial ATP synthase is more complex. The quasi-quantitative relationship between the prokaryotes and the chloroplast F1 subunits is 3 3 δ the total molecular volt rise is about 400, and the quasi-quantitative relationship of each subunit is only that of bacteria is accurately determined as ab2c10 12, and the minimum quasi-quantitative relationship of each subunit of chloroplast F0 is estimated to be 12, and the total molecular weight is about 160 kd.

F1 is the extramembranous part of the enzyme, with 3 subunits and 3 subunits alternately arranged to form a symmetrical orange petal-like structure. The F0 chitans number on the membrane, and the A and B subunit dimers are arranged on the outer side of the ring formed by the 12 C subunits. The two parts of the membrane and the extramembrane are connected by a neck structure composed of several small subunits such as , , and B2.

The neck structure that connects F0 and F1 can be divided into two parts: and the "rotor" composed of subunits located at the ** site of the enzyme, and the "stator" composed of subunits such as δ and B2. In the process of synthesizing or hydrolyzing ATP, the AND subunit rotates under the impetus of the proton flow through F0, and interacts with the three subunits in turn to regulate the conformational change of the catalytic site on the subunit. The "stator" δ and B subunits are much finer than the neck structure located at enzyme **, which connects 3 3 to F0 on one side.

Answer]: The most accepted model for ATP synthase to synthesize ATP is the binding change model. The model considers f1

The subunit acts as a rotating rod fixed at the center of rotation of the C subunit, which causes F1 when rotated

Complex subunit configuration changes. There are 3 different conformational states of the binding capacity of subunits to nucleotides, which have different binding abilities to ATP and ADP: idle state (type O), which hardly binds to ATP, ADP, and PI; In the loose binding state (L-type), the binding to ADP and PI is stronger; The tightly bonded state (T-type) is tightly bound to ADP and PI, and ATP can be generated and firmly bound to ATP.

When the subunit rotates and converts f1

The transformation of the complex subunit into the O-type releases synthetase, which is how the synthesis of ATP is promoted by air-by-breathing, which is thought to be carried out according to the pattern of "rotational catalysis": H+

When the flow is transported across the membrane, it drives the wheel-like structure of the ATP synthase base and the shaft connected to it to rotate, just as the water flow drives a water turbine. This rotation then causes a certain conformational change in the three blades (i.e., three subunits) connected to the shaft, and in the first step, with the emergence of conformational change, the loosely bound ADP and PI are converted into ATP; In the second step, the binding of ATP becomes more loose; The release of ATP may occur after the second step. Because the conformational changes are closely related, so that at any time, the three subunits are in different conformational states, and only one site is in the compact conformational state at a certain time, and the interchange of covalent bonds occurs in the compact state, and each system conformational change releases an ATP, and each subunit needs to undergo three conformational changes to form an ATP.

First, the nature is different.

1. Hexokinase: Hexokinase is a transferase with low specificity.

2. Glucokinase: Glucokinase is an inducible enzyme, and insulin can induce its synthesis.

Second, the characteristics are different.

1. Hexokinase: inhibited by glucose-6-phosphate and ADP, it has small KM and strong affinity, and can act on a variety of six-carbon sugars.

2. Glucokinase: plays a role in maintaining the constant blood sugar.

Hexose is a six-carbon sugar, so hexokinase can act on a variety of six-carbon sugars, while glucokinase is specific to glucose.

ATP is an allosteric inhibitor of fructose phosphokinase, reflex (coward).

a.The vertical hole is confirmed.

b.Mistake. Correct Answer: a

1. The synthesis and decomposition of ATP require the catalytic action of enzymes, such as ATP synthetase;

2. In the process of gene expression, the transcription process requires the joint participation of enzymes and ATP, and the same is true for the translation process, which means that the synthesis of enzymes (protein-type enzymes) needs ATP to provide energy;

3. The occurrence of enzymatic reactions often involves changes in energy, that is, it is closely related to the currency ATP.