Fragmentation-related phosphorylations

The P-aryl phosphanorbomenes (85 and 104) prepared by us served as excellent model compounds in photoinduced fragmentation-related phosphorylations. On the one hand, new //-phosphinates (105) were synthesized (Scheme 27), while on the other hand, our experiments indicating a high sensitivity towards the steric effects substantiated the AE mechanism involving a pentacoordinated pentavalent intermediate (106) (Scheme 28) [74, 75],... 

Scheme 29 The role of steric factors in the fragmentation-related phosphorylation...

Despite the aromatic character, the arylphospholes could also participate in Diels-Alder reactions to give new type of 7-phosphanorbomenes. These products together with phosphanorbomenes obtained by the regio- and stereospecific dimerization of arylphosphole oxides were useful model compounds in the UV light mediated fragmentation-related phosphorylation of alcohols. A novel mechanism was substantiated. 

The Diels-Alder reaction of 1,2-dihydrophosphinine oxides with dienophiles, such as acetylenic derivatives and maleic acid derivatives affords 2-phosphabicyclo [2.2.2]octadiene and 2-phosphabicyclo[2.2.2]octene 2-oxides that may be regarded as the precursors of low-coordinate, methylenephosphine oxides that are useful in the phosphorylation of 0- and N-nucleophiles. It was observed that the photo-chemically induced fragmentation-related phosphorylation may follow a novel addition-elimination mechanism instead of the classical elimination-addition protocol. 

As thermal examinations suggested, the phosphabicyclo[2.2.2]octadienes were used in thermo-induced fragmentation-related phosphorylations. It was possible to phosphinylate non-volatile phenol and naphthol derivatives by heating their sample with precursor 80 at 240 °C in the absence of any solvent. The esters (PhP(0)(OAr) Me) were obtained in 51-73% yield after chromatography [54] (Scheme 34). 

Diels-Alder Cycloadditions, Fragmentation-Related Phosphorylations, and Inverse Wittig-Type Reactions 563... 

DIELS-ALDER CYCLOADDITIONS, FRAGMENTATION-RELATED PHOSPHORYLATIONS, AND INVERSE WITTIG-TYPE REACTIONS... 

Staurosporine, a kinase inhibitor, also suppressed PAL transcription and enzymatic activation, which indicates that the phosphorylation of still unknown (transcription) factors happened in response to stimulation by pectic fragments. However, another staurosporine-insensitive but salicylic acid responding pathway led to the transcription of pathogenesis related (PR) genes [26]. 

APOE is fonnd in amyloid plaqnes and NFTs in AD brains. The accumulation of potentially pathogenic C-terminally truncated fragments of APOE depends on both the isoform and the cellular source of APOE. Neuron-specific proteolytic cleavage of APOE-A is associated with increased phosphorylation of tau and may play a key role in the development of AD-related neuronal deficits (514). Hippocampal APOfi levels correlate with NFT formation (Braak stages), especially in APOE-3/3 autopsy samples, but not in APOE-4 carriers (515). 

LC20 phosphorylation produces two pronounced effects it promotes the ability of myosin monomers to assemble into filaments, and it markedly increases (100-fold) the ATPase activity of myosin compared to un-phosphorylated filamentous myosin. How unphosphory-lated myosin filaments can remain stable is not certain, but may be related to binding to myosin of independently expressed MLCK fragments containing the myosin binding domain of MLCK. How LC20 phosphorylation increases the ATPase activity so dramatically is still unknown. 

CD is effective in inhibiting isometric force in Triton-permeabilized gizzard fibers (Szpacenko et al., 1985 Pfitzer et al., 1993). The actin-binding fragment of CD desensitizes the force-RLC phosphorylation relation, and the inhibitory effect is reversed by high concentrations of Ca +ZCaM (Pfitzer et al., 1993). In addition, CD peptides that act to displace CD from thin filaments are effective in enhancing force at fixed Ca + in isolated permeabilized smooth muscle cells (Katsuyama et al.,... 

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