Modifying group

A photoaffinity label is a molecule that forms a highly reactive excited state when illuminated with light of an appropriate wavelength. While in this excited state the photoaffinity label can covalently modify groups on the enzyme molecule that are in close proximity to the label. Hence one can mix the compound and enzyme... 

The hydroxylic content of the dextran sugar backbone makes the polymer very hydrophilic and easily modified for coupling to other molecules. Unlike PEG, discussed previously, which has modifiable groups only at the ends of each linear polymer, the hydroxyl functional groups of dextran are present on each monomer in the chain. The monomers contain at least 3 hydroxyls (4 on the terminal units) that may undergo derivatization reactions. This multivalent nature of dextran allows molecules to be attached at numerous sites along the polymer chain. 

Variations within the modifying group (e.g., oligosaccharide) create microheterogeneity... 

Figure 1.8 UV-visible spectra of ORMOSIL-embedded naphthopyrans with different modifying groups show that samples prepared with iBu and Ph groups lead to more significant shifts to the UV compared with samples prepared with the same relative amount of Me groups. (Reproduced from ref. 16,... 

Diol -(CH2)3 OCH2CH(OH)CH2(OH) Surface modifying groups for silica packings used in SEC... 

Effect of modifying groups on characteristics of modified lipase. The... 

Fig. 5 Effect of the fatty acid chain length and unsaturation degree of lipase modifying group on transesterification. Triolein (5mg) and linoleic acid (50mg) and modified lipase (1mg) reacted at 37°C In hexane (1mL). (Adapted from ref. 4.)...

In another important class of regulatory enzymes, activity is modulated by covalent modification of the enzyme molecule. Modifying groups include phosphoryl, adenylyl, uridylyl, methyl, and adenosine diphosphate ribosyl groups (Fig. 6-30). These groups are generally linked to and removed from the regulatory enzyme by separate enzymes. 

The maleimide functionality has also been utilized as a modifying group to obtain polymers crosslinkable by free radical chemistry. Thus, hydroxy-terminated poly(oxy-2,6-dimethyl-1,4-phenylene) (164) was treated with p-maleimidobenzoyl chloride (165) to obtain resin (166 Scheme 81) (72FRP2122181). Resin (166) melted at 155 °C and could be coated on to... 

Pyrazolines have also been incorporated as modifying groups by 1,3-addition of azomethine ylides to the carbon-carbon double bond of unsaturated poly(esters) (186 Scheme 89) (68MI11100). Poly(isoxazolines) were prepared in similar fashion by reaction of an unsaturated polymer with a nitrile oxide (75MI11106). 

Ma, P., and X. Zhao, Modified Group Contribution Method for Predicting the Entropy of Vaporization at the Normal Boiling Point. Ind. Eng. Chem. Res., 1993 32, 3180-3183. 

All amino groups can be trifluoroacetylated with ethyl thioltrifluoro-acetate (105). The product has no enzymic activity toward RNA. The modifying groups can be removed with 1 M piperidine at 0°. Interestingly, the resulting protein had little activity, was sensitive to trypsin, and had altered spectral properties. All of these properties were normalized after reduction and reoxidation of the disulfide bonds. 

When the vapor phase is generated at a solid interface rather than in the bulk of the liquid, the process is known as heterogeneous nucleation. Heterogeneous nucleation theories on smooth surfaces yield similar expression to Eq. 8.6-1 for J, with modified groupings A and B that account for the contribution of geometry and energy of the solid surface (22). 

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