Effects of molecular structure on two-dimensional phase diagram and thermodynamic quantities of mixed monolayers

Many kinds of two-component mixed monolayer systems were investigated to clarify the effect of molecular structures on the monolayer state. Two-dimensional phase diagrams and thermodynamic quantities were evaluated by correct thermodynamic analysis. The diagrams were classified into the following six types: (1) cigar type; (2) modified cigar type; (3) positive azeotropic type; (4) negative azeotropic type; (5) eutectic type; (6) complicated type. Phase diagram analysis and thermodynamic quantities, such as entropy, enthalpy and energy changes, were in good agreement with each other.     

Analysis of photosystem II using particle II preparation III. Roles of cytochrome b559 with different redox potentials and plastocyanin in the photosynthetic electron transport system

1. Using the P-II preparation (photosystem II preparation),the functional sites for Cyt-b₅₅₉ with different redox potentialsand for plastocyanin in the non-cyclic electron transport chainof chloroplasts were investigated. 2. In the absence of plastocyanin, the P-II preparation showedno light-induced absorption changes in Cyt-b₅₅₉. However, uponthe addition of a sufficient amount of plastocyanin, remarkablephotooxidation of this cytochrome was observed at room temperature. 3. Parallel measurements of the light-induced absorption changesin both Cyt-b₅₅₉ and plastocyanin revealed a close relationshipbetween them, and indicated that Cyt-b₅₅₉ and plastocyanin arelocated in series on the main path of the electron transportchain involving two photoreactions in PS-II. 4. Difference spectra and action spectra for the light-inducedabsorption changes in Cyt-b₅₅₉ and plastocyanin offered additionalevidence in support of the above conclusion. 5. Analysis of the relationship between the activity of ferricyanideHill reaction and the contents of Cyt-b₅₅₉ of different redoxpotentials showed that both forms of Cyt-b₅₅₉ (i.e. high- andlow-potential forms) play important roles under physiologicalconditions, being on the main pathway of the electron transportchain connecting PS-II and PS-I. 6. To these findings it is possible to give reasonable explanationsbased on our scheme presented previously, which suggested thatPS-II contains not one but two different photoreactions. Thisscheme is much more elaborately supported by this study whichshows the functional sites for Cyt-b₅₅₉ with two different potentials. ¹This work has been supported by a Grant from the Ministry ofEducation (Grant No. 844004), which we gratefully acknowledge.Part of this report has been presented at the Gordon ResearchConference on Regulatory Mechanisms in Photosynthesis, at Tilton,N.H., U.S.A., Aug. 13–17, 1973. (Received June 20, 1974; )