Sequences of donor and acceptor

The following sequences of donor and acceptor strengths have been obtained ... 

In enzymatic aoss-acyloin condensations, four different chiral acyloins can be expected to be formed from the cross- and homo-acyloin condensations (Scheme 10.2). Product distribution (chemoselectivity) will depend on the properties of the ThDP-dependent carboligase, that is, the binding sequence of donor and acceptor to the active site, the substrates, and their stoichiometric ratio [14],... 

Fig. 6.21. Principle of detection of lipopolysaccharide (LPS) with the CD14-derived probe. It relies on the formation of a ground state complex between fluorescein and rhodamine in aqueous solution with quenching of donor and acceptor fluorescence. Spectrum A shows hypothetical fluorescence emission spectra of this complex. After LPS binding, the peptide sequence gets straightened prohibiting the close contact between the two fluorophores and leading to the recovery of red fluorescence (Spectra B).

As discussed above, the photosynthetic reaction center solves the problem of rapid charge recombination by spatially separating the electron and hole across the lipid bilayer. In order to achieve photoinitiated electron transfer across this large distance, the reaction center uses a multistep sequence of electron transfers through an ensemble of donor and acceptor moieties. The same strategy may be successfully employed in photosynthesis models, and has been since 1983 [42-45]. The basic idea may be illustrated by reference to a triad Dj-D2-A, where D2 represents a pigment whose excited state will act as an electron donor, Di is a secondary donor, and A is an electron acceptor. Excitation of D2 will lead to the following potential electron transfer events. 

Of 43 337 pairs of donor and acceptor splice sites (splice pairs) 22 489 were supported by EST sequences. 98.71% of those contain canonical dinucleotides GT and AG for donor and acceptor sites. 0.56% hold non-canonical GC-AG splice site pairs. The reminder 0.73% occurs in a lot of small groups (with maximum size of 0.05%). 53.6% of canonical and just 27.3% of non-canonical splice pairs were supported by ESTs. Based on these figures it was supposed that at least half of annotated non-canonical sites presents annotation errors, as was shown in some previous works [8, 17]. 

With the site-selective hole injection and the hole trapping device established, the efficiency of the hole transport between the hole donor and acceptor, especially with respect to the distance and sequence dependence, were examined. Our experiments showed that hole transport between two guanines was extremely inefficient when the intervening sequence consisted of more than 5 A-T base pairs [1]. Hole injection into the DNA n-stack using photoexcited dCNBPU was accompanied by the formation of dCNBPU anion radical. Therefore, hole transport would always compete with the back electron transfer (BET). To minimize the effect of BET, we opted for hole transport between G triplets, that are still lower in oxidation potential than G doublet. With this experimental system, we researched the effect of the bridging sequence between two G triplets on the efficiency of hole transport [2]. 

Yet another approach uses peptides as tethers for intramolecular glycosylations via prearranged glycosides (Scheme 5.113) [326,327]. The regio- and anomeric selectivity of the intramolecular glycosylation depends on the amino acid sequence of the peptide, which links glycosyl donor and acceptor. 

On the basis of Scheme 5, we recently realized label-free sequence-specific DNA detection with SNP selectivity with the aid of SI nuclease [59]. In this assay, IBr and TO are chosen as the energy donor and acceptor, respectively. 

Figure 11-4. Splicing of a eukaryotic RNA transcript. A hypothetical hnRNA with two exons (EI and E2) and a single, large intron (I) is shown. Splicing can be divided into two main reactions initial attack of ribose near an A residue within the intron on the splice donor followed by attack of the newly available 3 end of exon I (EI) on the 5 end of exon 2 (E2) with coincident release of the intron. Special sequences surround the splice donor and acceptor sites. All steps occur within the spliceosome complex.

Typical aromatic donors and acceptors undergo only minor geometry changes upon oxidation or reduction or upon population of the triplet state for these compounds, the reaction sequence ET followed by BET has no effect on the structure. If the triplet state or biradical belongs to a different stmcture type than radical ion and ground-state precursor, as is the case for cis- or fraui-1,2-diphenylcyclopropane (65) or norbornadiene (16) BET may occur with cleavage or for-mation of one or more C—C bonds. In such cases, the sequence ET-BET may... 

The signal sequences that determine the location of splicing are shown in Fig. 1.47. Decisive are sequences at the border between exon and intron, foimd as conserved sequences at the 5 (donor site) and 3 (acceptor site) of the splice site. The intron is removed in the form of a lasso. Donor and acceptor sites are then precisely joined together. 

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