Just some correction Belum ditentukan caranya bekerja light didalam retina. Yg diketemukan adalah oxydative modification dari nitrotyrosine didalam protein dan mungkin perubahan ini mengakibatkn recognition of light didalam brain[saya tidak tahu bukan specialist dibidang ini]. Nitrotyrosine ini adalah identifier yg dapat dipakai utk menyelidikan macam2 penyakit dan bukan merupakan energy producer utk synthese. Mengenai deepsea bacteria, Saya tidak dapat mengerti similaritynya sebab untuk idantify protein sangat sulit dan theoretically apa yg ditulis dibawah adalah tidak mungkin. Yg mungkin bahwa sebagian characteristicnya sama. Binatang dideepsea cara mendapat energynya sangat lain - Kalau dibawah sinar matahari secara explain simple kita mendapat energy dari oxidasi seperti H2 + O2 jadi energy. Didalam deepsea cara mendapat chemical energie lain jaitu dari sufidication atau H2 + S2 jadi energy. Energy yg diciptakan oleh sulfidisatie ini oleh semacam chemical [saya lupa] dapat dirubah menjadi chemical energie - ADP/ATP etc.] Protein didalam ilmu biokimia adalah semacam katalisator untuk merendahkan energy dan limit point yg diperlukan utk melakukan reaksi kimia. Ini sangat berlainan dgn tanaman. Didalam photosynthese light biasannya yg 690nm [tergantung tanaman atau machluknya] ini bisa dirubah menjadi ADP atau ATP atau NADP yg didalam ilmu kimia biochemistry merupakan energy source yg dapat ditransport dan yg dapat dipakai untuk energy synthese kimia didalam tubuh. Jadi hanya tanaman dan beberapa chlorophyl bacteria [Chorella} yg sanggup merubah light kedalam energy. Kelebihan light itu harus diabsorbsi oleh tanaman - ini bisa 80-90 % dari cahaya yg diterima oleh tanaman. Untuk mengurangi danger ini mereka ada macam2 mechanisme antara lain secara kimia dan secara mechanic dgn pelindungan diri dgn bahan2 kering atai lilin atau penguapan air. .Memang warna2 bisa absorbsi energy dari sinar matahari tetapi ini limited dalam dia punya colour. - tetap masih banyak energy yg harus di buang. Kadang2 ada tanaman yg menerima dilain frequency tetapi yg dapat mereka merubah agar chlorophyl itu secara indirect dapat merubahnya jadi chemical energie tsb.Ini dapat kita ketemukan dihutan2 dimana cahaya yg masuk dibawah tidak cukup utk synthese di690nm, atau didalam bacteria diAlgae dilaut Ini hanya info diberikan agar kalian jangan misunderstanding atau mendapat misperception. Ini field masih open utk research tetapi masih merupakan basic study dan belum dapat dipakai sebagai applied science.
Andreas Dara Shayda <[EMAIL PROTECTED]> wrote: Salaam & Wow! This is amazing thanx for posting very important find. Did you know that the 2 proteins that absorb Red Green & Blue in our retina are the same proteins found in the bacteria found at the bottom of the ocean, I believe converting light to energy? These are important topics to think about. --DARA --- In [email protected], rahardjo mustadjab <[EMAIL PROTECTED]> wrote: > > > > January 20, 2005 news releases | receive our news > releases by email | science beat > > > Key Molecule in Plant Photo-Protection Identified > Contact: Lynn Yarris (510) 486-5375, [EMAIL PROTECTED] > > BERKELEY, CA � Another important piece to the > photosynthesis puzzle is now in place. Researchers > with the U.S. Department of Energy's Lawrence Berkeley > National Laboratory (Berkeley Lab) and the University > of California at Berkeley have identified one of the > key molecules that help protect plants from oxidation > damage as the result of absorbing too much light. > > The researchers determined that when chlorophyll > molecules in green plants take in more solar energy > than they are able to immediately use, molecules of > zeaxanthin, a member of the carotenoid family of > pigment molecules, carry away the excess energy. > > > > (teks foto) > From left, Graham Fleming, Nancy Holt and Kris Niyogi, > of Berkeley Lab's Physical Biosciences Division, have > identified a key molecule in the photo-protection > mechanism of green plants. > > This study was led by Graham Fleming, director of > Berkeley Lab's Physical Biosciences Division and a > chemistry professor with UC Berkeley, and Kris Niyogi, > who also holds joint appointments with Berkeley Lab > and UC Berkeley. Its results are reported in the > January 21, 2005 issue of the journal Science. > Co-authoring the paper with Fleming and Niyogi were > Nancy Holt, plus Donatas Zigmantas, Leonas Valkunas > and Xiao-Ping Li. > > Through photosynthesis, green plants are able to > harvest energy from sunlight and convert it to > chemical energy at an energy transfer efficiency rate > of approximately 97 percent. If scientists can create > artificial versions of photosynthesis, the dream of > solar power as a clean, efficient and sustainable > source of energy for humanity could be realized. > > A potential pitfall for any sunlight-harvesting system > is that if the system becomes overloaded with absorbed > energy, it will likely suffer some form of damage. > Plants solve this problem on a daily basis with a > photo-protective mechanism called feedback > de-excitation quenching. Excess energy, detected by > changes in pH levels (the feedback mechanism), is > safely dissipated from one molecular system to > another, where it can then be routed down relatively > harmless chemical reaction pathways. > > Said Fleming, "This defense mechanism is so sensitive > to changing light conditions, it will even respond to > the passing of clouds overhead. It is one of Nature's > supreme examples of nanoscale engineering." > > The light harvesting system of plants consists of two > protein complexes, Photosystem I and Photosystem II. > Each complex features antennae made up of chlorophyll > and carotenoid molecules that gain extra "excitation" > energy when they capture photons. This excitation > energy is funneled through a series of molecules into > a reaction center where it is converted to chemical > energy. Scientists have long suspected that the > photo-protective mechanism involved carotenoids in > Photosystem II, but, until now, the details were > unknown. > > Said Holt, "While it takes from 10 to 15 minutes for a > plant's feedback de-excitation quenching mechanism to > maximize, the individual steps in the quenching > process occur on picosecond and even femtosecond > time-scales (a femtosecond is one millionth of a > billionth of a second). To identify these steps, we > needed the ultrafast spectroscopic capabilities that > have only recently become available." > > The Berkeley researchers used femtosecond > spectroscopic techniques to follow the movement of > absorbed excitation energy in the thylakoid membranes > of spinach leaves, which are large and proficient at > quenching excess solar energy. They found that intense > exposure to light triggers the formation of zeaxanthin > molecules which are able to interact with the excited > chlorophyll molecules. During this interaction, energy > is dissipated via a charge exchange mechanism in which > the zeaxanthin gives up an electron to the > chlorophyll. The charge exchange brings the > chlorophyll's energy back down to its ground state and > turns the zeaxanthin into a radical cation which, > unlike an excited chlorophyll molecule, is a > non-oxidizing agent. > > > > > Green plants use photosynthesis to convert sunlight > to chemical energy, but too much sunlight can result > in oxidation damage. > > To confirm that zeaxanthin was indeed the key player > in the energy quenching, and not some other > intermediate, the Berkeley researchers conducted > similar tests on special mutant strains of Arabidopsis > thaliana, a weed that serves as a model organism for > plant studies. These mutant strains were genetically > engineered to either over express or not express at > all the gene, psbS, which codes for an eponymous > protein that is essential for the quenching process > (most likely by binding zeaxanthin to chlorophyll). > > "Our work with the mutant strains of Arabidopsis > thaliana clearly showed that formation of zeaxanthin > and its charge exchange with chlorophyll were > responsible for the energy quenching we measured," > said Niyogi. "We were surprised to find that the > mechanism behind this energy quenching was a charge > exchange, as earlier studies had indicated the > mechanism was an energy transfer." > > Fleming credits calculations performed on the > supercomputers at the National Energy Research > Scientific Computing Center (NERSC), under the > leadership of Martin Head-Gordon, as an important > factor in his group's determination that the mechanism > behind energy quenching was an electron charge > exchange. NERSC is a U.S. Department of Energy > national user facility hosted by Berkeley Lab. > Head-Gordon is a UC Berkeley faculty chemist with > Berkeley Lab's Chemical Sciences Division. > > "The success of this project depended on several > different areas of science, from the greenhouse to the > supercomputer," Fleming said. "It demonstrates that to > understand extremely complex chemical systems, like > photosynthesis, it is essential to combine > state-of-the-art expertise in multiple scientific > disciplines." > > There are still many pieces of the photosynthesis > puzzle that have yet to be placed for scientists to > have a clear picture of the process. Fleming likens > the on-going research effort to the popular board > game, Clue. > > "You have to figure out something like it was Colonel > Mustard in the library with the lead pipe," he says. > "When we began this project, we didn't know who did > it, how they did it, or where they did it. Now we know > who did it and how, but we don't know where. That's > next!" > > Berkeley Lab is a U.S. Department of Energy national > laboratory located in Berkeley, California. It > conducts unclassified scientific research and is > managed by the University of California. Visit our > Website at www.lbl.gov. > > Additional Information > For additional information visit the Website at > http://www.lbl.gov/pbd/photosynthesis/default.htm *************************************************************************** Berdikusi dg Santun & Elegan, dg Semangat Persahabatan. Menuju Indonesia yg Lebih Baik, in Commonality & Shared Destiny. www.ppi-india.uni.cc *************************************************************************** __________________________________________________________________________ Mohon Perhatian: 1. Harap tdk. memposting/reply yg menyinggung SARA (kecuali sbg otokritik) 2. Pesan yg akan direply harap dihapus, kecuali yg akan dikomentari. 3. 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