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l h e relationships between electron transport and photosynthetic carbon metabolism were measured i n maize (Zea mays 1.) leaves following exposure to suboptimal temperatures. l h e quantum efficiency for electron transport i n unchilled leaves was similar to that previously observed in C, plants, although maize has two types of chloroplasts, mesophyll and bundle sheath, with PSll being largely absent from the latter. The index of noncyclic electron transport was proportional to the CO, assimilation rate. Chilled leaves showed decreased rates of CO, assimilation relative to unchilled leaves, but the integral relationships between the quantum efficiency for electron transport or the index of noncyclic electron transport and CO, fixation were unchanged and there was no photoinhibition. The maximum catalytic activities of the BensonCalvin cycle enzymes, fructose-1,6-bisphosphatase and ribulose-1,5-bisphosphate carboxylase, were decreased following chilling, but activation was unaffected. Measurements of thiol-regulated enzymes, particularly NADP-malate dehydrogenase, indicated that chilling induced changes in the stromal redox state so that reducing equivalents were more plentiful. We conclude that chilling produces a decrease in photosynthetic capacity without changing the interna1 operational, regulatory, or stoichiometric relationships between photosynthetic electron transport and carbon assimilation.l h e enzymes of carbon assimilation are particularly sensitive to chilling, but enhanced activation may compensate for decreases in maximal catalytic activity.

The Suzuki±Miyaura cross-coupling reaction using heterogeneous Pd/C has a homogeneous component. The soluble palladium concentration increases during the reaction reaching a maximum at ca. 90% conversion before falling to < 4 ppm.

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