Calvinism

The student who is interested in details of the physical principles involved and of further applications of ion exchange should consult Ion Exchanges in Organic and Biochemistry by Calvin Calmon and T. R. E. Kressman. (Inter- cience Publication Inc., New York.)... 

Branch, G. E. K. Calvin, M. (194s). The Theory of Organic Chemistry. New York Prentice-Hall. 

First (Van Cleef Arpels 1977) White Linen (Lauder 1978) T Air du Temps (spig carnation) L Air du Temps (Ricci 1948) Paris (Yves Saint Laurent 1984) Eternity (Calvin Klein 1988)... 

Chamade (Guedain 1970) Chanel No. 19 (Chanel 1971) Calvin Kleiu (Kleiu 1978) Safari (Ralph Lauren 1990)... 

Lauren (Lauren 1978) Escape (Calvin Kleiu 1991) L eau D Issey (1992)... 

M. Calvin and J. A. Bassham, The Photosynthesis of Carbon Compounds, Benjamin, New York, 1962. 

Brunner, Calvin. Design of Sewage Sludge Incineration Systems. Noyes Data Corporation 1980. 

The reasonable extension of these ideas is to express o- as a sum of contributions from the inductive and resonance effects. Branch and Calvin suggested this, and much of the research on LFER of the past three decades has been concerned with... 

Branch, G.E.K. Calvin, M. "The Theory of Organic Chemistry Prentice-Hall New York, 1941 p417. 

The set of reactions that transforms 3-phosphoglycerate into hexose is named the Calvin-Benson cycle (often referred to simply as the Calvin cycle) for its discoverers. The reaction series is indeed cyclic because not only must carbohydrate appear as an end product, but the 5-carbon acceptor, RuBP, must be regenerated to provide for continual COg fixation. Balanced equations that schematically represent this situation are... 

Each number in parentheses represents the number of carbon atoms in a compound, and the number preceding the parentheses indicates the stoichiometry of the reaction. Thus, 6(1), or 6 COg, condense with 6(5) or 6 RuBP to give 12 3-phosphoglycerates. These 12(3)s are then rearranged in the Calvin cycle to form one hexose, 1 (6), and regenerate the six 5-carbon (RuBP) acceptors. 

The Calvin cycle enzymes serve three important ends ... 

Most of the enzymes mediating the reactions of the Calvin cycle also participate in either glycolysis (Chapter 19) or the pentose phosphate pathway (Chapter 23). The aim of the Calvin scheme is to account for hexose formation from 3-phosphoglycerate. In the course of this metabolic sequence, the NADPH and ATP produced in the light reactions are consumed, as indicated earlier in Equation (22.3). 

Balancing the Calvin Cycle Reactions To Account for Net Hexose Synthesis... 

FIGURE 22.23 The Calvin-Benson cycle of reactions. The number associated with the arrow at each step indicates the number of molecules reacting in a turn of the cycle that produces one molecule of glucose. Reactions are numbered as in Table 22.1. 

FIGURE 22.27 Light-induced pH changes in chloroplast compartments. Illumination of chloroplasts leads to proton pumping and pH changes in the chloroplast, such that the pH within the thylakoid space falls and the pH of the stroma rises. These pH changes modulate the activity of key Calvin cycle enzymes. 

Compartmentation of these reactions to prevent photorespiration involves the interaction of two cell types, mescrphyll cells and bundle sheath cells. The meso-phyll cells take up COg at the leaf surface, where Og is abundant, and use it to carboxylate phosphoenolpyruvate to yield OAA in a reaction catalyzed by PEP carboxylase (Figure 22.30). This four-carbon dicarboxylic acid is then either reduced to malate by an NADPH-specific malate dehydrogenase or transaminated to give aspartate in the mesophyll cells. The 4-C COg carrier (malate or aspartate) then is transported to the bundle sheath cells, where it is decarboxylated to yield COg and a 3-C product. The COg is then fixed into organic carbon by the Calvin cycle localized within the bundle sheath cells, and the 3-C product is returned to the mesophyll cells, where it is reconverted to PEP in preparation to accept another COg (Figure 22.30). Plants that use the C-4 pathway are termed C4 plants, in contrast to those plants with the conventional pathway of COg uptake (C3 plants). 

Eormadon of PEP by pyruvate Pi dikinase reini-dates the cycle. The CO9 liberated in the bundle slieadi cell is used to syndiesize hexose by die convendonal rubisco-Calvin cycle series of reacdons. 

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