Covalent modification Volume

Wood modification can improve the dimensional stabilization of wood by two mechanisms. Where the cell wall is filled in some way by the reagent (whether covalently bound or not), the cell wall is swollen. When the dimensional stability of the modified wood is subsequently determined, the wood can then only swell by an additional amount, which is dependent upon the bulking of the cell wall due to the volume occupied by the modifying agent. This is illustrated in Figures 2.8 and 2.9b. 

These results indicate that there is no competition between NjPjAZg and EtdBr and suggest that NjPjAz does not interact with DNA through an intercalation process but through covalent binding. This is supported by the fact that there is no modification of the fluorescence decrease after 10 dialyses against 200 volumes of 10 M NaClO. Furthermore, it is possible to separate on a gel column (Sepharose 6B) the NjPjA which has reacted with DNA from the free compound and in that way to follow the kinetics of the complexation (data available on demand). 

Tanaka and his coworkers have used Flory s formula with several modifications to understand a discrete phase transition in ionic gels. First, the term Vo IV in Eq. 3 was replaced by the term

volume fraction of the network on condition that the constituent polymer chains have random-walk configurations [5]. Flory assumed that the dry gel (in other words, the network formed by cross-linking of the unswollen polymer at volume V0) satisfies the condition of no polymer interactions i.e., covalently cross-linked PAAm gels in an acetone-water mixture therefore he claimed that the elastic term is generally not a function simply of V0/V (=[Pg.594]

It was shown that the polyribosomal form of mRNP complexes is actively translated, whereas the free form is not. One mi t expect that a covalent chemical modification of some of the mRNA proteins, such as ADP-ribosylation, will render the mRNA available for translation. We characterized the mRNA-associated ADP-iibosyl transferase in plasmac) oma, in Krebs II, ascite tumor cells, and in liver. Several auto(ADP-ribosylated) proteins could be obtained when mRNP particles were incubated with NAD. It is unlikely that we are dealing with a contamination of chromatin since in plasmocytoma the enzymatic activity in mRNP represent 34% of the total cellular activity, while the maximum DNA contamination is only 4%. Moreover, after DNAse hydrolysis the enzymatic activity remains unchanged and addition of DNA is without effect [31]. More information on these mRNP particles will be given by Thomassin et al. (this volume). 

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