Hydrolysis curves

The rotations were measured in chloroform solution, a fact which is not stated in the original article. The hydrolysis curves for aqueous solution of difructose anhydride III indicate that the rotation in water of the resulting trimethyl-D-fructose is also within this range. 

Typical hydrolysis curves for a variety of celluloses are shown in Fig. 2. As has been noted by various investigators,9i20,21 the curves indicate rapid initial hydrolysis followed by a slower hydrolysis and are... 

The data show that the extent of the hydrolysis of starch by the amylase of Aspergillus oryzae depends within wide limits upon the concentration of amylase used. Like those for pancreatic amylase already discussed (Figure 2), these hydrolysis curves show a change from a rapid to a slow phase of the reaction and tend to flatten at higher values as the concentration of amylase is increased. Again, with different concentrations of the amylase of Aspergillus oryzae there is no evidence of a common limit such as is observed with different concentrations of beta amylase (Figure 1). 

Tables XI and XII summarize data obtained by Myrback86 for the hydrolysis of amylose by purified maltase-free malted barley alpha amylase. The hydrolysis curve with this linear substrate is much the same as those obtained with unfractionated starches, and also is similar to the curves representing the hydrolysis of amylose by pancreatic amylase.41 The flattening of the hydrolysis curves during the later stages (86) K. H. Meyer and P. Bernfeld, Helv. Chim. Acta, 24, 359E (1941).

The hydrolysis curves for the three alpha amylases considered in this review are all similar in shape. They show a rapid hydrolysis in the early stages with a slow secondary stage of hydrolysis which cannot be explained as due either to inactivation of the enzymes or to the influence of products formed during the hydrolysis. The extent of the hydrolysis and the position of the break in the hydrolysis curve depend upon the concentration of enzyme the break in the hydrolysis curve does not appear to be a fixed point characteristic of any one enzyme. With each of the alpha amylases discussed here the slowing down of the hydrolysis appears to be due largely to the replacement of the original substrate by products for which the amylase has relatively low affinity. 

Hydrolysis Curves. Figure 1 shows the two hydrolysis curves obtained by hydrolysis of Purina 500 E with Alcalase and Neutrase, respectively. The difference in kinetics between the two enzymes is apparent from the difference in shape of the two curves. The hydrolysis curves also serve to indicate the hydrolysis time needed to reach a desired DH-value. 

Figure 1. Hydrolysis curves for soy protein isolate hydrolyzed with alcalase and...

Modification of Ultrafiltered versus Acid Precipitated Soy Protein. When the retentate obtained from the ultrafiltration of soybean extract is subjected to an enzymatic hydrolysis as described earlier (2) for acid precipitated protein, a hydrolysis curve (DH versus time) may be drawn. A comparison of such hydrolysis curves is shown in Fig. 2 for acid precipitated soy protein isolate and ultrafiltered soy protein isolate. The curves are drawn on the basis of the same hydrolysis parameters. The enzyme used is the microbial alkaline protease subtilisin Carlsberg (ALCALASE ). 

Basis for the kinetic model is a standard batch hydrolysis experiment ( ). Fig. lA shows the standard hydrolysis curve for soy protein isolate - Alcalase. The reaction constant (pseudo first order rate constant) is calculated from the standard curve by fitting the inverse curve in a small DH-range 1 3 ) to a se-... 

Figure 15, The reaction constant, k(DH), from the standard hydrolysis curve...

In batch hydrolysis experiments we have generally not distinguished between S and P, but have assumed S = P for the standard hydrolysis curve. However, the distinction between S and P is crucial in the present case where inert protein (Nx6.25) accumulates. P denotes the protein concentration in the beginning of the experiment. 

Figure 3 shows that beyond 750 rev/min for the hydrolysis (curve A) and beyond S(X)rev/min for oxidation the speed (curve B) had no effect on conversion and hence on the rates of reaction, thereby indicating absence of liquid-to-membrane surface mass transfer resistance both inside and outside the capsules. The reaction could be taken as kinetically controlled and governed by eq.(5) beyond the said speeds in each case. This was further confirmed by studying the effect of temperature and the values of activation energies, which will be discussed later. Since the capsules were well dispersed in the agitated outer phase the bulk concentration of benzyl chloride within a capsule would be uniform. Further experiments were conducted beyond these speeds which were safe to maintain the fidelity of the capsules. 

It has already been emphasized (p. 14) that the best stage of hydrolysis at which to attempt the fractionation of peptides is at the point where enzyme action will proceed no farther or when there is a very sharp break in the hydrolysis curve. The disadvantage of a long incubation period is of course that the danger of rearrangements increases (see Linder-str0m-Lang and Ottesen, 1949). 

GD dissolves in water but the rate of hydrolysis under neutral conditions is slow (Yang et al. 1992). Qualitatively, the hydrolysis of GD is similar to that of GA however, the reaction rate is fivefold slower than that of GA, and GD has an estimated half-life of about 60 hr at pH 6 and 25 °C (Hambrook et al. 1971). The reaction is both acid- and base catalyzed, resulting in a hydrolysis curve similar to that of GA (Clark 1989). The primary hydrolysis product of GD is pinacolyl methylphosphonic acid, which slowly hydrolyzes, with the release of pinacolyl alcohol, to methyl phosphonic acid (Fig. 6) (Clark 1989 Kingery and Allen 1995). At pH >10, hydrolysis to pinacolyl methylphosphonic acid occurs within a few minutes (Yang et al. 1992). Because an acid is produced, the pH will decrease, lessening the rate of hydrolysis. GD stored at pH 6 for 8 wk had a pinacolyl methylphosphonic acid/methyl phosphonic acid ratio of 250 (Hambrook et al. 1971), which Kingery and Allen (1995) extrapolated to a half-life of 27 yr. The C-P bond is very resistant to hydrolysis. Hydrolysis products are listed in Table 37. 

Also shown in Figure 3 is TP hydrolysis of PAM in aqueous solution as measured by the titration method. The data shown were obtained via three separate aging experiments. For comparison with the aqueous hydrolysis curve determined by ammonia analysis, a similarly complex curve has been drawn through the composite data for the three titration experiments. Such a curve appears to give a reasonable fit to the data, but is admittedly arbitrary. Without benefit of the ammonia analyses (curve b), one would probably be inclined to represent the titration data as a smooth curve. A similar comment applies to curve a of Figure 3. 

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