MCB102-11 - MCBlOZ Fall 2008 Photosynthesis Carbon-Fixing...

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Unformatted text preview: MCBlOZ Fall 2008 Photosynthesis Carbon-Fixing Reactions Reading: pages 7 7 8—786. Omit the section on transport on pages 788 and 784. Outline 1. Three carbon dioxide molecules react with three 5-carbon phosphorylated sugars to make six three carbon compounds. 2. One out of six of these three carbon compounds goes into glycolysis or sugar synthesis. 3. Five out of six of these three carbon compounds are reduced and rearranged to regenerate the three 5-carbon phosphorylated sugars. 4. The enzyme that fixes carbon dioxide into two 3-carbon compounds (RUBISCO) is inefficient and non—specific. 5. Several of the enzymes responsible for fixing carbon dioxide into carbohydrate are inactivated when light is absent. About 200 years ago, Jean Senebier showed that plants use carbon dioxide during photosynthesis. For the first 150 years thereafter, no one knew the reaction in which C02 is taken up, because no one knew how to trace the carbon of carbon dioxide. Kamen and Ruben make 140 In 1940 Samuel Ruben and Martin Kamen at the Lawrence Berkeley Laboratory had made the short-lived radioisotope 11C (t 1/. : 20 min) and wondered whether they could make a longer-lived radioactive isotope of carbon. They bombarded graphite (120 with some 130) with deuterons (a neutron plus a proton) and got a tiny amount 140, derived from the 130, in a reaction in which a deuteron expels a proton (d, p). 14C has a half-life of about 5,000 years. Kamen and Ruben then noticed that a bottle of ammonium nitrate sitting near the cyclotron had become radioactive. It contained 140 methane. Kamen and Ruben then bombard ammonium nitrate with fast neutrons, and the 14N gave 140 in high yield in a reaction where a neutron replaces a proton (n,p). Kamen and Ruben realized that 14C could be used to trace the path of carbon dioxide into carbohydrate, and Willard Libby, another Berkeley Chemistry Professor, realized that 140 could be used to date organic materials. Kamen and Ruben were diverted to the Manhattan project to make the atomic bomb at Los Alamos National Laboratory. At Los Alamos, Ruben was given a defective vial containing phosgene (COClz)and died of phosgene poisoning. Kamen asked a colleague who ran the cyclotron machine to prepare radioactive sodium for an experiment. When Kamen opened the container of sodium, he was surprised that it was glowing purple, signifying a much more intensely radioactive batch than could be produced in the cyclotron of which he was aware. He deduced immediately that the sodium must have been irradiated in an atomic reactor elsewhere in the laboratory. Because of security, he had not been told of its existence. In his excitement, he blurted out his belief to colleagues. Shortly after, an investigation was launched to find out who had leaked the information to him. When he returned to his regular work at Berkeley, Kamen met two Russian officials at a party given by his close friend, the Violinist Isaac Stern. Kamen had toyed With a musical career, and accompanied Stern as a viola—player in social evenings of chamber music. One Russian asked how he might find help to get experimental radiation treatment for a colleague with leukemia. Kamen made inquiries, and in appreciation the official invited him for dinner at Bernstein's Fish Grotto in San Francisco. Since the Oak Ridge incident, FBI agents had kept Kamen under surveillance. They observed the dinner, and Kamen was sacked shortly thereafter. He got a job at Washington University in Saint Louis, Where he could work on mammalian metabolism, but not on photosynthesis. Later, he became a professor at U. C. San Diego. fiat: Figure 2. Samuel Ruben (left) and Zev Hassid (right); late 19303 or early 19403; photograph reproduced by courtesy of Dr George C. Ruben, Damnouth College. During the summer of 1947, the author (HG) visited Hassid in Berkeley to learn how to prepare 14 - - C—labeled radioactive glucose from plant leaves that had been exposed to 1“(:02 and light. Martin Kamen 1913-2002 MeIw'n Calvin carries on After the Second World War, the US. National Labs could supply 140 in the form of 14002. Melvin Calvin, a Chemistry professor at UC Berkeley, was affiliated with Lawrence Berkeley National Lab, and he got 14002 to use as a tracer. Calvin grew the alga Chlorella in the presence of light and administered radioactive carbon dioxide for 5 seconds. Then he lysed the algae and placed their low molecular weight contents on paper. He electrophoresed them, and then he chromatographed them in a second dimension (at right angles to the direction of electrophoresis), to separate the metabolites. Most of the label appeared in 0-1 of 3-phosphoglycerate. When he applied radioactive 002 to algae for several minutes, he found that the concentration of ribulose 1,5-bisphosphate increased. This led him to propose that CO2 was not added to a two carbon compound, but that a 5-carbon sugar was split, and at the same time (302 was added to the Z-carbon part. 9mg; 9‘. 1. Figure 20.2 Tracing the fate of carbon dioxide. Radioactivity from 14C0; is incorporated into 3~phosphoglycerate within 5 s in irradiated cultures of algae. After 60 s, the radioactivity appears in many compounds, the intermediates within the Calvin cycle. [Courtesy of Dr. J. A. Bassham.] 002 withdrawal 1 Reservoir size Time (min) FIGURE 2432 Algal 3BPG and RuBP levels on removal of C02. The time course of the levels of 3P6 (purple curve) and RUBP (great curve) in steadyetate I4(IOz—labeled, illuminated algae is shown during a period in which the C02 (orange curve) is abruptly withdrawn. In the absence of C02, the 3P0 concentration rapidly decreases because it is taken up by the reactions of the Calvin cycle but cannot be replenished by them Converselyg the RuBP concentration transiently increases as iii synthesized from the residual pool of Calvin cycle intermediates but, in the absence of C02, cannot be used for their regeneration. The carbon-fixing reaction is ribulose 1,5-bisphosphate + C02 -) 2 3«phosphog1ycerate page 3 The radioactive carbon of carbon dioxide goes to C-1 of 3-phosphoglycerate. The enzyme that catalyzes this reaction is called ribulose bisphosphate carboxylase/oxygenase, or "RUBISCO." The kcat of this enzyme is only 3/sec, which is even worse than chymotrypsin. Thus, in order to have enough activity, this enzyme must be abundant. It constitutes 50% of the protein in the stroma, Where its concentration is 250 mg/ml. It is the most plentiful enzyme on earth. Calvin’s proposed mechanism is the abstraction of hydrogen from 0—3 of ribulose 1,5-bisphosphate to give an enediolate intermediate, Which attacks carbon dioxide nucleophilically. The resulting [3- keto acid is then attacked by water to give the two identical three carbon products. Since Calvin’s time we have learned that RUBISCO must have a carbamoylated lysine in order to be active. We shall return to this matter later. The RUBISCO reaction releases a great deal of free energy: -52 kJ/mol, or almost as much as the hydrolysis of 2 ATP. Thus the reaction is thermodynamically very favorable, as well as kinetically very slow. O a (IIH20PO§“ cHzoPog‘ (I; (131.com? o==c ‘o—~ C/P‘J ll) H0-C-cc“ 2 Fnz-B‘rlifémOH g G H O I A HGUR H—~(I}-*OH H~?-—OH H-C “OH E 24-34 Probable reaction mechanism of the — ~ ~ I carboxylation reaction catalyzed by RuBP carboxylase. The CH20PO§ CH20PO§ CHZOPO? reaction proceeds via an enediolate intermediate that RuBP Enediolate B-Keto acid nucleophilically attacks CO; to form a B—keto acid. This H'_O\ intermediate reacts with water to yield two molecules of 3PG. H H‘r 3311201303” H+ fHZOPog‘ _ d z c 0P02' HO—?~COZ -——~7 Ho—c—co; 1H2 3 / HO -— C — CO" H + _...7z—-- no fire-2 3PG l .i H”~ C ~ OH O\ [/0 l (’3 CH20PO§ 3PG H—c-—0H CHEOPOE” In order to regenerate the ribulose 1,5-bisphosphate, it is necessary to start With three of these molecules, make 6 molecules of 3-phosphoglycerate, and then use 5 of them to regenerate 8 molecules of ribulose 1,5«bisphosphate. This leaves one molecule of 8-phosphoglycerate as the product that goes into sugar synthesis or glycolysis. It is customary to draw reactions that convert all six molecules of 3—phosphoglycerate into glyceraldehyde-3~phosphate. The first two regenerative reactions come from glycolysis: the 3-phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase are run in reverse, WW - NADPH u DPf o ‘ OCC/G Ute/0903’ 414* A ‘5“ i “750 {’03, PHoSFHov . t G “ASE H C UFO " GLYCEKRTE HLcoPog ’DEHYDKO E 2, 3 9‘? KINASE GAP I33 bnspbosrllo“ alvcem‘le The remainder of the pentose regeneration reactions can be summarized as follows: C3 +03 9 C6 C3 + C6 9 C4 + C5 CB + C4 9 C7 CB + C7 9 C5 + C5 5 C3 9 3 C5 Remember a C3 +03 9 C6 reaction from glycolysis? It's the aldolase reaction. In order to have the right substrates, one has to convert glyceraldehyde-B- phosphate to dihydroxyacetone phosphate in the triose phosphate isomerase reaction. When Calvin found fructose 1,6-bisphosphate labeled with 14C in carbons 3 and 4, he realized that the stroma of chloroplasts must have triose phosphate isomerase and’aldoloase, and this turned out to be true. 0: TKlOSE COH ‘ , 60.00.; - 0 $*‘ «Max PHATE “’1 HI; 3 H19-“ HcoH {SOMERASE .230 $5 “10 9'0 HLCO P0; W HLCOPO; Hose“ “0.9” H “A HooH F33 Pm “4° My _ MAP W s _ HGOH p.35 DH 00L HQ ' , w/AL l - H CO (303' r H (:0 903' 4 2- V 1, f; - With NADPH+ in place of NADH+. These reactions use up most of the NADPH and ATP generated in the light reactions. Paafl 5 If one removes the phosphate at carbon 1 of fructose 1,6-bisphosphate with a phophatase, as one does in gluconeOgenesis, then one gets fructosefi— phosphate, which is a substrate for transketolase. Transketolase transfers CZ units from ketoses to aldoses, and in this case it. transfers two carbons from fructose 6-phosphate to glyceraldehyde 3-phosphate to give xylulose-S— phosphate and erythrose-él-phosphate. HQoH o; H TRMS' 0“?“ 0:30 2920 iii“ KETOLASE Hm“ + 1403);; H09“ ‘ + I 2 M ' H i Hana M10903 m) “9° , H90“ , “€10” « 99.? 9,90%; Hélopoa' “£0903. Hum ((058 xvuuose FRucToSSPEWE 4. PH05 PHR TE 5‘ PHOSPHATE (r9140 Aldolase then condenses dihydroxyacetone phosphate with erythrose 4- phosphate to give sedoheptulose 1,7-bisphosphate, and the phosphate on carbon-1 is removed by sedoheptulose bisphosphatase to give sedoheptulose— 7-phosphate. - H H190 P03, H1990 9: 0 ngo HEPTuLoSE Hog; or?“ H190“ 35°0ng HogH BtSPHOSfHATASE : H Md H90“ + $=0 M—«a HpoH ,.~7_./-—) 3g“ $3203," “£0903 “90” H10 H‘gou L H . 1 Eamaose DHAP HHEZPO ; H2C°P°3 ‘tMosWfiTE 1” 3 SepoHEPTuwSE SE DOHEPTuLOSE 7, mos PHATE l, 7 65 PHOS 961W Transketolase then removes two carbons from sedoheptulose 7 -phosphate and transfers them to glyceraldehyde 3-phosphate, giving xylulose 5— phosphate and ribose 5-phosphate. Ll CO“ I 0. Lisa 0 mans— ‘EHH “.199 H Hoéu ‘9“ Know“ “9" 9:0 MM 4’ “0°” M “$0” + New ' €090 ’ “(PP HCOH ’ Wm H’” 3 H6090 '« Wm "CID" a M p {60583 “LCoP03 : Hiccf’os s PHoSpHATE XYLMLOS e senoHemwSE 5- PHosPH ATE 7. PHoSPHATE Both of these sugars are converted to ribulose 5-phosphate, one by an epimerase and one by an isomerase. Ribulose 5-phosphate kinase then acts on ribulose 5-phosphate and ATP to give ribulose 1,5-bisphosphate, which can start another round of the Calvin Cycle. All of the enzyme activities of this cycle are found in animal cells except for rubisco, an aldolase that can use a 7-carbon sugar, and the phosphatase for a 7-carbon sugar. HCOH RIBMLOSE “‘6014' 5-?H03PHRTE - 1 ISOMEKASE RIBMLOSE HaCoPog 5- PHOSPH A TE pause 7 An overview of the Calvin cycle is given below. In the diagram below three ribulose 1,5-bisphosphates and three carbon dioxides give six 8- phosphoglycerates and then six GAPS. One of these GAPS goes to hexose synthesis or perhaps glycolysis. We are left with 5 GAPS to regenerate 8 ribulose 1,5 bisphosphates. Two of these GAPS become DHAP. GAP + DHAP yields fructose 1,6- bisphosphate and then fructose 6-phosphate. The transketolase reaction with GAP gives xylulose 5-phosphate + erythrose 4- phosphate. Erythrose 4-phosphate + DHAP give sedoheptulose 1,7 bisphosphate in an aldolase reaction, and then sedoheptulose 7-phosphate. Sedoheptulose 7-phosphate and GAP give ribose 5-phosphate and another xylulose 5-phosphate in a transketolase reaction. One isomerization and two epimerizations give three ribulose 5-phosphates which are kinased to three ribulose 1,5 bisphosphates. Ribulose 5-phosphate 3 ATP 3 ADP Xylulose Ribose 5-phosphate 5-phosphate GAP Sedoheptulose 7-phosphate Ribulose 1,5-bisphosphate Pr H20 3-Phosphoglycerate Sedoheptulose 1,7-bisphosphate 6 ATP Figure 20.12 Calvin cycle. The xyluros e 6 ADP diagram shows the reactions necessary with the correct stoichiometry to convert three molecules of C02 into one molecule of dihydroxyacetone phosphate (DHAP) The cycle is not as simple as presented in Figure 20]; rather. it entails many reactions that lead ultimately to the synthesis of glucose and the regeneration of ribulose l.5—bisphosphate. [After J. R. Bowyer and R; C Leegood. “Photosynthesis,” in Plant Biochemistry P. M Be): and LB. Harbome. Eds. (Academic Press, 1997), p. 85.] DHAP Erythrose 4-phosphate 5-phosphate GAP Fructose 6~phosphate Fructose 1,6-bisphosphate A GAP Peta} g 1,3-Bisphosphoglycerate 6 NADPH 6 NADP‘“ Energy balance of the Calvin cycle To make 6 glyceraldehyde 3-phosphates initially, or one net GAP eventually, we need to fix 3 carbon dioxides with 3 ribulose 1,5 bisphosphates. This means that 6 ATPs will be needed in the phosphoglycerate kinase reaction. Six NADPHs will be needed in the GAP dehydrogenase reactions. Three ATPs will be needed in the ribulose 5-phosphate kinase reactions. Thus 6 + 3 = 9 ATP are needed and 6 NADPH are needed to make one glyceraldehyde 3- phosphate. This means 3 ATP and 2 NADPH per carbon dioxide. This may be why the textbook suggests that 3 ATP are made per 2 NADPH in photo- phorphorylation. One way to remember 2 NADPH per C02 is the following: reduction of carbon dioxide with one NADPH gives a theoretical formic acid, and reduction of formic acid with another NADPH gives formaldehyde, which has the oxidation state of carbohydrate. 5" .9 CO;L +2H-HCOH +5214 —> HCH +Hao Berkeley’s rewards for Calvin Calvin’s work was done in an old wooden building that has since been torn down. After his success he got his own Department of Chemical Biodynamics for himself and two other faculty members. This department had its own circular building, the Laboratory of Chemical Biodynamics, which still stands on the west side of Gayley Road, across from Kleeberger Field and Memorial Stadium. More bad news about RUBISCO: the oxygenase reaction You know already that RUBISCO has a low turnover number. RUBISCO also has difficulty distinguishing between carbon dioxide and oxygen. At the current atmospheric concentrations of oxygen and carbon dioxide, every third reaction uses oxygen instead of carbon dioxide: as follows: CHzO—® I Ribulose 1,5-bisphosphate HMCII—OH Enediol form I O Enzyme-bound intermediate 2-Phosphoglycolate 3-Phosphoglycerate FIGURE 20-20 Oxygenase activity of rubisco. Rubisco can incorpo~ rate 02 rather than C02 into ribulose 1,5-bisphosphate. The unstable intermediate thus formed splits into 2—phosphoglycolate (recycled as described in Fig 20421} and 3—phosphoglycerate, which can reenter the Calvin cycle. The 2-phosphoglycolate produced is metabolized into useful products by an expensive series of reactions that involve two oofactors that you have not seen yet, Therefore, we won‘t go through those expensive and complicated reactions. You textbook presents some philosophy that rationalizes the existence of the RUBISCO oxygenase reaction: when photosynthesis begana there was not much oxygen in the atmosphere} so the oxygenase reaction did not matter. 9432 10 The Calvin Cycle is turned off in the dark The reactions of the Calvin Cycle used to be called the “dark reactions,” because it was assumed that light was not necessary for them. It turns out that several enzymes of the Calvin Cycle require light to be activated. This makes sense, since there is no need to fix carbon dioxide into carbohydrate in the absence of energy. Here is one example of light activation of an enzyme of the Calvin Cycle: FIGURE 20—8 Role of rubisco activase in the carbamoylation of Lys2m of rubisco. When the substrate ribulose 1,5-bisphosphate is bound to Rubiscé, _ ,. _ ,, the active site, Lys2m is not accessible. Rubisco activase couples ATP ‘ V /0”® hydrolysis to expulsion of the bound sugar bisphosphate, exposing if CH2 » Lyszm; this Lys residue can now be carbamoylated with C02 in a re— H I OH RUNS“) With action that is apparently not enzyme—mediated. Mg2+ is attracted to H O uandified Py 5201 and binds to the negatively charged carbamoyl—Lys, and the enzyme 2 (I: H ilglbbioufid “Elise is thus activated. it; inagéivgsp a img ‘ O P rubisco activase ADP Ribulose 1,5—bisphosphate - A W a ATP-dependent if removal of fibulose Lysml ' 1,5 bisphosphate \ + uncovers e-amino NH3 group of Lyszm. 2 C02 /’N‘\\ 'Mg2*i \-,// {fry 5' 9951131110 group ei'Lysm1 is, carbanioylated thy (202; i Met-2“ bin \ Warbamoyi‘ Lye, activating hibisé’o. 53 “"i an RUBISCO require a carbamoylated lysine201 and a bound magnesium ion in order to function. The carbamoylation is not very stable. When the carbamoyl group is lost, RUBISCO binds ribulose the presence of light, an enzyme called 1,5-bisphosphate nonproductively. In RUBISCO activase cleaves ATP to ADP and phosphate and removes the ribulose 1,5-bisphosphate. This allows spontaneous carbamoylation and magnesium ion binding by RUBISCO, When then becomes active for a short time. Why is light required? In the presence of light, photosystem I reduces ferredoxin, which reduces a small protein called thioredoxin, which reduces and activates RUBISCO activase. When light is absent, oxygen oxidizes RUBISCO activase, and it becomes inactive again. Four other enzymes of the Calvin Cycle are reduced and activated by thioredoxin. Light Fdred V713 ferredoxina PhOtOSYStem I Lh iorodoxin reductase Fd0X ,-/ ‘7‘?” HS FIGURE 20-19 Light activation of several enzymes of the Calvin cycle. The light activation is mediated by thioredoxin, a small, (disulfide- containing protein. in the light, ihiorodoxin is reduced by electrons moving from photosystem l through ferredoxin (Fd) {blue arrows), then ihioredoxin reduces critical disulfide bonds in each of the enzymes puffie 11 {\Tliiqredoxin HS SH 4-- Enzyme \i (active) \\ _// 02 (in dark) / ,. Enzyme NR] i (inactiVei SWS H. sedoheptulose 1,7—bisphosphatase, fructose 1,6-bisphosphatase, ribu~ lose Esphosphate kinase, and glyceraldehyde 3-phosphate dehydroge— nase, activating these enzymes. In the dark, the —-SH groups undergo reoxidation to disulfides, inactivating the enzymes. Terms and concepts Calvin cycle Enzymes in order of use: Rubisco (ribulose bisphosphate carboxylase/oxygenase) Phosphoglycerate kinase GAP dehydrogenase Triose phosphate isomerase Aldolase Fructose bisphophatase Transketolase Aldolase Sedoheptulose bisphosphatase Transketolase Phosphopentose isomerase Phosphopentose epimerase Ribulose 5-phosphate kinase Light regulation of Calvin Cycle enzymes Structures to memorize Glyceraldehyde Glyceric acid Dihydroxyacetone Erythrose Ribose Ribulose Xylulose Fructose Sedoheptulose Page 13 Problems 1. Place the following sugar conversions in the correct order used to regenerate starting material for the Calvin cycle, and name the enzyme that catalyzes each reaction: a. Cv-ketose + Cg—aldose -) Cs-ketose + Cs-aldose b. Ce-ketose + Cg-aldose 9 C4-aldose + Cs-ketose c. C4-aldose + Cs—ketose -) C7-ketose 2. How many moles of ATP and NADPH are required to convert 6 moles of (302 to fructose 6-phosphate? 3. What is the first stable radioactive sugar intermediate seen when 14002 is added to algae? When the supply of 14C02 is cut off, what compound accumulates? What do these results suggest about the pathway of (302 incorporation into carbohydrates? 4. Outline the synthesis of fructose 6-phosphate from 3-phosphoglycerate. 5. Draw the reactants and products of the reaction that fixes carbon into carbohydrate in photosynthesis, and name the enzyme that catalyzes the reaction. An abbreviation of the name is sufficient. 6. Where in the ribulose 1,5-bisphosphate molecule is the C02 that is being “fixed” added? Answers 1. The correct order is b, c, a. Transketolase catalyzes reactions (a) and (b), whereas aldolase catalyzes reaction (0). 2. Eighteen moles of ATP and twelve moles of NADPH are required to fix six moles of 002. Here is the calculation, based on each mole of carbon dioxide fixed. Two moles of ATP are used by phosphoglycerate kinase to form two moles of 1,3-bisphosphoglycerate, and one mole of ATP is used by ribulose 5- phosphate kinase to form one mole of ribulose 1,5 bisphosphate per mole of C02 fixed. Two moles of NADPH are used by GAP dehydrogenase to form two moles of glyceraldehyde 3-phosphate per mole of 002 incorporated. Therefore three moles of ATP and two moles of NADPH are used for each mole of 002 fixed. 3. 3-phosphoglycerate is the first stable sugar that incorporates the 14002. This result by itself (in isolation) suggests that 14002 is added to a 2-carbon compound. Ribulose LES-bisphosphate levels increase after the removal of 14002, which instead suggests that ribulose 1,5-bisphosphate is the 14002 acceptor. 4. Phosphoglycerate kinase converts two molecules of 3-phosphoglycerate, the initial products of photosynthesis, to two molecules of the glycolytic intermediate 1,3-bisphosphog1ycerate, which are then converted to glyceraldehyde 3-phosphate by an NADPH-dependent glyceraldehyde 3- phosphate dehydrogenase. Triosephosphate isomerase converts one molecule of glyceraldehyde 3-phosphate into dihydroxyacetone phosphate, which aldolase condenses with the remaining glyceraldehyde 3-phosphate to form fructose 1,6-bisphosphate. The phosphate ester at 0-1 is hydrolyzed by fructose 1,6-bisphosphatase to give fructose 6-phosphate. The result of this pathway, which is functionally equivalent to the gluconeogenic pathway, is the conversion of the 002 fixed by photosynthesis into a hexose. 5. Ribulose-1, 5=bisphosphate + 002 9 2 3-phosphoglycerate H RUBISCO H 0.0 . ' . “‘9 l gill-0903‘ H.290 P03 8. The carbon dioxide that is fixed on ribulose 1,5—bisphosphate is attached to carbon-2. which had the keto group. Page I5 I. THVKE}; col REACT WT” [SENEBIER cor» 03 TAKEI; 5w suGRRS To MAKE I‘WO RUBENK KAMEN LBL SIX 3A COMPOUNDS. )GRAPHHEBE‘TDEUTERONS :2. ONE ouT 0F 31x OFWESE‘ A u, ,., THREE CARBON COMPOUNDS A AA ’ ,EOOOYERRS 9.0123 mm omomnxon N+NEMTR0NS~A C SMARSYNTHESIS, * HA3, LOS ALAMOS ~ 3. FIVE ouT OF- SIX OF THESE RABEN DIED OF PHOSGENE. MARBON COMPOUNDS ARE KAMEN ORDERED RADIOACTIVEM MODIFLE1>,.AAND RE ARRANGED [TFLuoREscgu HT: 3AA) “Tms T9 REGENERATE THE ORWLMASTAAVE BEEN MADE INA 3 5W5“ PHOSVHORYLATED REACTOR ELSEWHERE" HE WAS SHGARS- )PUT UNDER FBI SURVEILLANCE A. THE ENZYME TAAT FIXES HAD DINNER UITHRHSSMNS CoaANTo 2 3—CAKBON [POST WK » COMPOUNDS(RUBISCO) *IS -. A K I _ NATlONAL LABS MAKE CO SPECIFIC, 59 SEVERAL OF TH£ ENZYAASEw (“(10.1 5 SECONDS RESPONSIBLE FOR FIXWE TEAM; mm- (0; INTO CARBOHYDRATE REQUle LIGHT FOR ACTIVATION. Tr!“ + TOTEM!) . 1 .1 I4 .. 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MCB102-11 - MCBlOZ Fall 2008 Photosynthesis Carbon-Fixing...

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