Modification local chemical

Information about the putative folding of the H,K-ATPase catalytic subunit through the membrane has been obtained by the combined use of hydropathy analysis according to the criteria of Kyte and Doolittle [51], identification of sites sensitive to chemical modification [46,48,50,52-55], and localization of epitopes of monoclonal antibodies [56]. The model of the H,K-ATPase catalytic subunit (Fig. 1) which has emerged from these studies shows ten transmembrane segments and contains cytosolic N- and C-termini [53]. This secondary structure of the catalytic subunit is probably a common feature of the catalytic subunits of P-type ATPases, since evidence supporting a ten a-helical model with cytosolic N- and C-termini has also been published recently for both Ca-ATPase of the sarcoplasmic reticulum and Na,K-ATPase [57-59]. 

The chemical modification of nucleic acids at specific sites within individual nucleotides or within oligonucleotides allows various labels to be incorporated into DNA or RNA probes. This labeling process can produce conjugates having sensitive detection properties for the localization or quantification of oligo binding to a complementary strand using hybridization assays. 

Also, local changes in the structural and chemical variation of DNA may have important effects on the overall extent of chromatin folding. For instance, transitions from the B to the Z form of DNA will result in nucleosome dissolution (as discussed earlier) and this could affect the folding of the fiber. As well, chemical modifications of the bases such as methylation have been shown to increase the folding of the chromatin fiber when linker histones are present [250] although the mechanism involved in this later case remains to be elucidated. 

Yang P-Y, Liu K, Zhang C, Chen GYJ, Shen Y, Ngai MH, Lear MJ, Yao SY (2011) Chemical Modification and Organelle-Specific Localization of Orlistat-Like Natural-Product-Based Probes. Chem Asian J 6 2762-2775... 

As a native starch, lipids and protein residuals are significantly lower than they are in many other commercial starches. These properties of tapioca starch have been utilized in many industries and further enhanced by means of physical and/or chemical modifications which give close control of its properties to fit the needs of customers in process and product applications. However, tapioca starch is regarded as a specialty starch outside of its local production area. 

It should be stressed that proteins are more than just the sum of the amino acids that comprise them. Surprises abound when predicting the chemical modification behavior of a particular protein, largely because of the complex interplay between the individual functional groups and the local environments in which they reside. Nevertheless, the first step to understanding the chemical behavior of proteins is to characterize the reactive properties of the individual side chain groups. The following sections describe these aspects, with an emphasis on the chemical techniques that are commonly used to modify these residues for applications in chemical biology. 

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