Amylose reagent

Amylene, stabilizer for solvents 120 Amylose reagent 173 a-Amyrin 44,69 jS-Amyrin 69 a-Amyrin benzoate 63 Anabolics 303, 411, 430,432 Anacardol 288... 

Note The reagent can be employed on silica gel and cellulose layers. Starch can also be employed in place of amylose [2]. The blue coloration of the amylose complex turns brown after a short time. 

Amyl nitrite reagent lb 115 Amylose la 173 a-Amyrin la 44,63,69 P-Amyiin la 69... 

Of the methods available for potentiometrically estimating the amount of iodine bound by amylose, the differential method of Gilbert and Marriott36 is by far the most satisfactory for accurate work as it eliminates corrections for reagent blanks. In this method, the amylose solution and control solution form two half-cells connected by a salt-bridge, and the... 

Figure 14.7 Schematics depicting the assembly of QD-protein conjugates that engages in FRET near a surface. Step 1, the glass slide waveguide is coated with Avidin. Step 2, attach biotinylated MBP to Avidin on the surface as a linker. Step 3, self-assemble MBP-dye and avidin onto the QD surfaces. Step 4, purify the QD conjugate solution from 3 over amylose resin. Step 5, allows the QD assembly to attach to the MBP-Bt via its surface Avidin and wash away excess reagents. Adapted from reference 32.

An interesting observation is that an enzyme may exhibit different pH activity profiles for various neutral substrates. The explanation of this is that the enzyme binds or transforms such various substrates differently. For example. Taka amylase has different pH optima for long chain amyloses and for low molecular mass substrates. Some specific chemical modifications of the side chains of the enzyme may also alter the pH activity profiles. Kobayashi, Miura and Ichisima (1992) modified the lysine amino groups using bifimctional reagent o-phtalaldehyde, and observed a pronounced shift in the pH-dependence of ohgomaltoside hydrolysis. 

Jane, J. L., Xu, A., Radosavljevic, M., Seib, P. A. (1992). Location of amylose in normal starch granules. 1. Susceptibility of amylose and amylopectin to cross-linking reagents. Cereal Chem., 69,405 09. 

The great majority of experimental variants discussed for benzylation (see Sect. 2.1) has also been applied for the preparation of allyl ethers. Among them, the alkylation with allyl bromide and sodium hydride in a dipolar aprotic solvent is most frequently used for complete allylation. Reaction with the methylsulfinyl carbanion in DMSO to form an alkoxide, followed by the reaction with allyl bromide provides a convenient high-yield route to 2,3,6-tri-O-allyl-amylose [227], With the limited amount of reagent, 35% of methyl 2-0-allyl-3,6-dideoxy-a-D-xy/o-hexopyranoside was synthesized from the corresponding glycoside [228]. The 2-allyl ether was the major product (43 % yield) of the reaction of methyl 4,6-0-benzylidene-a-D-glucopyranoside with allyl bromide and 1.1 equiv. of sodium hydride in benzene [71]. 

Amylose is a polysaccharide. Its glycoside linkages are inert to Benedict s reagent, but the terminal glucose residues at the ends of the chain and its branches are hemiacetals in equilibrium with open-chain structures. A positive test is expected. 

Assay procedures there are three accepted methods in assaying branching enzyme (BE). One measures the decrease in absorbance of the glucan-I3 complex that results from the branching of amylose or amylopectin. The assay mixture containing amylose or amylopectin is incubated and aliquots are taken and iodine reagent is added.35,247 The decrease of absorbance is measured at 660 nm for amylose and at 530 nm for amylopectin. 

In favorable cases, a selective precipitant can be used. A classic example is the separation of amylose and amylopectin, by precipitation of the amylose by a variety of reagents. 

Acid conversions when starch is treated with an acid such as HCI or H2SO4 at 40-60°C (commonly a starch slurry with 35-40% solids is treated with 0.2-0.5 N HCI for a few hours). Following the acid conversion, the acid is neutralized. In this process, the DP value decreases (and several physical properties are modified). Although chemical studies show that the a-D-(1- 4) links are more sensitive to hydrolysis than a-D-(1->6) links, it was determined that due to starch crystallinity more a-D-(1->6) links are hydrolyzed [55]. This happens because the a-D-(1 6) links are in the amorphous regions and they are more accessible to the reagent (less hydrogen bonds). This explains why the DP of amylose is reduced less than that of the amylopectin component. 

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