Excitation energy distribution

Staehelin, L.A. and Amtzen, C.J. 1983. Regulation of chloroplast membrane function. J. Cell Biol., 97,1327-1337. Steinback, K.E., Bose, S. and Kyle, D.J. 1982. Phosphorylation of LHC regu-lates excitation energy distribution between PSII and PSI. Arch. Biochem. Biophys., 216. 356-361. 

Delta-P and Delta-E Matrices Prediction of Molecular Geometric Relaxation, and Excitation Energy Distribution... 

To take advantage of the simplicity of this mechanism, two types of recoil experiments are used. Studies at low (P/Z) provide a lower-bound result for the CF3 F excitation energy distribution. High-pressure experi-... 

Below 3.9 atm (see above) collisional deactivations of the excited intermediates in cascade sequence Equations 81-84, are effectively suppressed, so that the decomposition product yields mirror the imper-turbed excitation energy distribution (16,25,31,34,45,47). Each... 

The fractional product yields and decomposition threshold energies corresponding to the mechanism shown in Reactions 77-84 have been shown in Table XIII. On simple thermochemical grounds the detection of CClg F product shows that the nascent CFs F excitation energy distribution extends to at least 15 eV. 

Figure 3. Approximate lower-bound thermochemical excitation energy distribution for F-for-F activated CFs F (49)...

In Figure 3 the fractional product yields measured at 1.3 atm and corrected for statistical losses of F have been plotted against the decomposition threshold energies obtained from standard enthalpies of formation. This lower-bound model for the CFs F primary excitation energy distribution extends to 20 eV even without inclusion of corrections for C F dissociation or for the translational energy carried away by the dissociated F atoms. 

A final refinement, which is not described here in detail due to space limitations, involves the derivation of an approximate continuous representation of the CF3 F excitation energy distribution from the data hsted in Table XIII (47,48,49). This is possible based on accurate fractional decomposition yields as input data due to the serial nature of the cascade sequence shown in Reactions 81-84. The continuous distribution corresponding to Figure 3 is shown in Figure 5. 

Significance of Thermochemical Excitation Energy Distributions. Two fundamentally different approaches have been used for the elucidation of primary product excitation distributions for hot atom activated species. Many workers have utilized the RRKM unimolecular rate theory to invert pressure falloff data measured for the products from energetic H-for-H (19,64,65,74,83,84,85) or F-for-X (19,27) substitution reactions. More complete citations to the early literature are given elsewhere (57,58,59,77,80). This inversion procedure is computationally straightforward. However, it involves several a priori untested and... 

Figure 8. Approximate thermochemical excitation energy distributions for the F-for-k alkyl replacement channels in CHfiHF (28, 77)...

The search for a phenomenological alternative to RRKM inversion distribution mapping does not represent a novel idea. The first step in the RRKM modeling procedure for a chemically activated species involves the a priori characterization of its initial excitation energy distribution (70,89,90). For species produced from exoergic reactions this information is normally obtained from thermochemical data. A correspondingly simple direct method has not yet emerged for hot atom activation processes, because the associated dynamics are incompletely imderstood. 

The following input data are required (i) a quantitative description of the initial excitation energy distribution function [f(Ei)] (ii) a set... 

Several conclusions follows from the results presented here and in previous sections (i) the nascent products from F-for-X reactions possess broad, peaked excitation energy distributions (ii) the unimolecular fallofiF comparisons shown in Figures 16 and 17 are based on nonsensical theoretical assumptions (iii) both multiple and demonstrably invalid theoretical models apparently can be rationalized with (P/Z) fallofiF data for F-for-X activated species (iv) Figure 17 supports the utility, but not the validity, of the underlying theoretical model and (v) fallofiF data comparisons of this type for recoil F activated systems in which f(E ) is not known a priori suflFer from severe uniqueness limitations. 

As a consequence, it is postulated that LHCII protein phosphorylation regulates excitation energy distribution between PSI and PSII... 

LHC II) plays a major role in this regulation (1). The mechanism of regulation of the excitation energy distribution is based on a balance between phosphorylated and dephosphorylated LHC II, with the redox-state of the plasto-quinone as a modulator of kinase/phosphatase activity. 

Recent work has been aimed at elucidating the possible role of a protein phosphorylation event in the regulation of excitation energy distribution between PS2 and PS 1 analagous to that reported for higher plants. When crude membranes are incubated... 

EFFECTS OF LOW TEMPERATURE ON CHLOROPHYLL PROTEIN COMPLEXES AND REGULATION CAPACITY OF EXCITATION ENERGY DISTRIBUTION IN CHLOROPLAST MEMBRANE OF CUCUMBER... 

In this paper, we report that the Chi—protein complexes are disintegrated and the mechanisms of regulation of the excitation energy distribution can be perturbed in leaves of cucumber submitted to chilling stress conditions. 

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