ATP synthesis protein machine

The structure of ATP synthase machinery is unique and worthy of mention. It is a multi-protein complex with a molecular mass of 500,000 daltons (1 dalton is equal to the molecular weight of a hydrogen atom). This gigantic protein machine resembles a mushroom which consists of a head, rotor and stator. The head is 10 nm across, and 8 nm high (lnm equals 1 billionth of a meter). This size is actually so tiny that, although it is one of the biggest protein complexes known, billions of billions of these machines would be required to cover a pinhead. ATP synthase is held to the inner membrane by its stator. In the center of the complex, there is a cylindrical rotor which connects die lollipop-shaped head to the stator. The stator is also in direct contact with the head region via an elongated arm which attaches the stator firmly to the head region.

Must strikingly, there is a narrow channel inside the stalk which allows the desperate H' ions to return to their homeland. Yet, in one of the most amazing pieces of machinery that the science has witnessed so far, this channel only allows H⁺ ions (or protons) to pass along it. If you can imagine how tiny these ions are, you can estimate the width of this channel. Other plus-charged ions, for example Na⁺ or K⁺ are slightly bigger in size and hence, they are not able to pass. The design of this marvelous channel is still a mystery to scientists. Since energy is the only currency for the continuation of life and that currency is ATP in living organisms, one can say that the lives of all humans, animals, plants and other organisms require that protons pass through this tiny channel.

As each proton passes inside the channel to reach the matrix, it causes a 120-degree counterclockwise rotation of the rotor that is hundreds of thousands times heavier than itself. Therefore, the potential energy of the hydrogen ions is converted to mechanical energy by diis molecular machine. The way ATP synthase works bears a metaphorical resemblance to manmade hydraulic machines. For example, old water mills, as shown in Figure 2, use hydraulic potential energy to rotate the mill. In a molecular machine, the voltage and concentration gradient is used to rotate the enzyme. Similar mechanisms are used nowadays in turbines placed on water domes to convert the energy from water flow to produce electromagnetic energy via rotation. In ATP synthase, each subunit of the head region can bind to ADP and phosphate, which cannot readily come together to form ATP. The rotation of the stalk causes a structural change in the protein surface of the head region that specifically enables this reaction to form the energy molecule.

It is by this mechanism that cells can produce more than 90% of their energy. Three or four H⁺ ions are needed to pass through the channel to rotate the whole machine. A single ATP synthase turns at an amazing 24,000 rotations per minute (rpm). Assuming that the engines of highly developed automobiles can only rotate at up to 10,000 rpm, die speed of rotation of this machine is highly impressive. Remarkably, the human body breaks down 100 kilograms of ATP in a day that is roughly equal to 10²⁶ molecules in number. Hence, billions of billions of ATP synthases need to work nonstop to supply our body with the required energy. They consume Hydrogen ions of roughly 1 kilogram of sugars (or fats) to produce sufficient ATP, which is usually what an average person eats per day.

The complexity of energy production in living organisms and use of highly divergent enzymes reminds us of the fact that biological processes are interconnected with each other. In order to start a single vital process, the cell needs to produce energy. Energy is stored in a chemical form of ATP whose synthesis requires enzymes, mitochondria, oxygen and intake of organic molecules. These enzymes are encoded from the genetic code, DNA, by a multi-protein complex, ribosome. This in turn needs energy to make die enzymes out of genetic code. The cycling of all these processes requires the recurrence of all the vital genes for energy production, DNA transcription, translation, cell division, and so forth. In addition, the necessity for the presence of gases, amino acids and other such factors raise questions about how life could have started spontaneously on Earth. Since we already know that the most primitive living organisms, or bacteria, have 30,000 genes and are highly complex, life is highly demanding. The example of how die energy molecule is produced is just a tiny example of the necessities of life. It is impossible to imagine that life could have started on Earth by mere chance.

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Refreshing Tips To refresh yourself and continue working even after hours, try these exercises!		Ергономічні поради Аби покращити своє само-почуття і продовжити робо-ту, скористайтеся цими вправами
With your thumb against the side of your index finger, gently apply pressure above the eye-brows and at several points aro-und the eye.		Складіть разом вказівний та великий пальці й легенько потріть область обличчя над бровами та навколо очей.
Press gently with your thumb and forefinger on either side of the bridge of your nose, massaging up and down three times.		Притисніть складені разом великий та вказівний пальці до перенісся і зробіть три масажні рухи вздовж лінії носа.
Use both thumbs to press just below your eyebrows. Hold for three to five seconds.		Великі пальці обох рук при-тисніть до повік і потримайте 3-5 секунд.
Spread your fingers until you feel the stretch. Hold for five seconds, relax, then bend for five seconds.		Максимально розправте паль-ці й потримайте їх у такому напруженому стані 5 секунд, а потім знову зігніть на 5 секунд.
Clasp your hands behind your head, and pull your shoulder bla-des in until you feel the stretch. Hold for five to ten seconds, then relax.		Сплетіть пальці рук на поти-лиці і спробуйте дотягнутися до лопаток, поки не відчуєте повне напруження м'язів. По-тримайте руки таким чином 5-10 секунд, потім розслаб-теся.
Massage the base of your thumb using slight pressure and a slow, circular motion. The same can be done to relieve tension spots in your neck, shoulders and forearms.		Помасажуйте основу велико-го пальця повільними круго-вими рухами. Так само можна послабити напруженість у рі-зних точках шиї, плечей та рук нижче ліктів.
With your right arm straight in front of you and your fingers relaxed and poin-ting down, flex your wrist up and down five to ten seconds, then relax.		Витягніть перед собою праву руку з розпрямленими, але не напруженими пальцями і 5 10 секунд позгинайте зап'ясток униз-угору, потім розслабте руку.
Lean forward to touch your toes, hold for five to ten seconds, then slowly return to an upright position.		Нахиліться додолу на 5 се-кунд, торкнувшись кінчиків своїх черевиків, а потім повільно випростайтеся.
Hold your right leg just below the knee, and hug it to your chest. Hold for five to ten sec-onds. Switch legs and repeat.		Візьміться рукою за ногу під коліном і спробуйте підтяг-нути її до грудей. Потримайте так 10 секунд. Поміняйте ногу і повторіть вправу.
The above exercises are recommen-ded by the US based Ergonomics Consortium. Info: www.scdetails.com		Ці вправи рекомендовані Ергоно-мічним консорціумом (США). Інфо: www. scdetails.com

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