Hydrolysis experiments

Somatostatin is a tetradecapeptide of the hypothalamus that inhibits the release of pituitary growth hormone. Its amino acid sequence has been determined by a combination of Edman degradations and enzymic hydrolysis experiments. On the basis of the following data, deduce the primary structure of somatostatin ... 

Remember that, by convention, the NH2 group of each amino acid is written at the left the COOH group is at the right Other reagents split the chain at different points. By correlating the results of different hydrolysis experiments, it is possible to deduce the primary structure of the protein (or polypeptide). Example 23.10 shows how this is done in a particularly simple case. 

Cellulase and all chemicals used in this work were obtained from Sigma. Hydrolysis experiments were conducted by adding a fixed amount of 2 x 2 mm oflSce paper to flasks containing cellulase in 0.05 M acetate buffer (pH = 4.8). The flasks were placed in an incubator-shaker maintained at 50 °C and 100 rpm. A Box-Behnken design was used to assess the influence of four factors on the extent of sugar production. The four factors examined were (i) reaction time (h), (ii) enzyme to paper mass ratio (%), (iii) amount of surfactant added (Tween 80, g/L), and (iv) paper pretreatment condition (phosphoric add concentration, g/L), as shown in Table 1. Each factor is coded according to the equation... 

Conditions for hydrolysis experiments were selected to simulate harsh reservoir environments. Moderately alkaline (pH 8.5) solutions, high temperatures, and long reaction times up to 120 days were used. The pH of the solutions remained at 8.5 or slightly higher, ensuring that all anionic groups were fully ionized. 

This behavior provides evidence that in each of the compounds, radon is in the +2 oxidation state When higher-valent xenon compounds, such as XeF and XeF, are hydrolyzed, water-soluble xenon species (XeO and XeO ) are produced (Malm and Appelman, 1969). We have observed no radon species corresponding to these xenon species in hydrolysis experiments. 

Barsha and Hibbert16 also demonstrated by meins of methylation, acetylation, acetolysis and hydrolysis experiments that the membranes synthesized by the action of A. xylinum on D-fructose and on glycerol were chemically identical with cotton cellulose. 

In a similar fashion, the cationic polymerization of 2-oxazolines has been extensively studied and was found to provide the first verified entry to linear-poly(alkyleneimine) architectures. These acylated polymers were first recognized as precursors to linear poly(ethyleneimines) in the early 1960s [25]. Hydrolysis experiments demonstrated that deacylation of these products to linear PEI was possible. The original polymerization mechanism proposed by Tomalia et al. 

Although adsorption of many types of species could be considered, this discussion will focus on surface hydrolysis reactions, that is, adsorption of H+ and OH . Virtually all surface hydrolysis experiments are carried out in the presence of a "background electrolyte," many of which appear to exhibit weak specific chemical interactions (e.g., ion-pair formation) with the surface (10-12). While consideration of these interactions is essential to a complete understanding of the interfacial chemistry, the topic is a subject in itself, and will not be considered in detail here. Treatment of these interactions is readily incorporated within the framework that is presented here. 

Stability and Performance of Bound En me. The stability of the IME was determined by two methods. One measurement of bound activity was obtained using traditional cellulose hydrolysis experiments (described below). In the other method, direct kinetic parameter measurements were obtained using a recirculating differential (RDR) reactor system following the method of Ford et al. (46). 

In order to study further the favorable aspects of in situ acid catalyzed hydrolysis, experiments were performed at different temperatures so as to evaluate the dependence of rate on temperature. Solutions of aldlcarb were passed through a jacketed column around which water at 30, 40, or 50°C was circulating. The ion exchange bed (5 cm x 0.70 cm) contained 2.0 g of Bio-Rad AG MP-50 strong acid cation exchange resin (iT ", 100-200 mesh), and the solution flow rate was approximately 1.0 ml/mln. The percent of Initial aldlcarb remaining at the end of the column for each temperature decreased from 76% at 30 C to 56% at 40 C and 35% at 50°C. Future temperature studies will be done in order to evaluate the practicality of temperature control in a detoxification filter unit. 

As a result of these various pretreatments, the hydrolysis experiments were carried out on three different starting materials autohydrolysed aspen wood made either in batch or in continuous equipment and the cellulosic residue of the autohydro-lysis-caustic extraction process. 

Source of Enzymes. Culture filtrates of T. reesei strains VTT-D-79125 and Rut C-30 were used as starting material for purification of the individual enzymes and also as crude enzyme preparations in the hydrolysis experiments. Cultivations were carried out in a laboratory fermentor at 30°C for 4d on media containing Solka floe cellulose (James River Corp., New Hampshire, USA), or glucose and distiller s spent grain (Alko, Ltd., Koskenkorva, Finland). 

Hydrolysis Experiments. The substrate in the hydrolysis experiments included alkali-extracted beechwood 4-O-methylglucuronoxylan, DMSO-extracted acetylated beechwood 4-O-methylglucuronoxylan, alkali-extracted wheat straw arabinoxylan and acetylated or deacetylated xylo-oligomers from steaming of birchwood (24). Deacetylation was carried out by incubating the freeze-dried xylo-oligomers in ammonia vapor overnight. Substrate concentration was 10 gl— 1, temperature 45° and hydrolysis time 24... 

The first derivative of 1,2,3-triazine to be prepared, the triphenyl compound (2, R = Ph), was obtained in 1960 by thermolysis of 1,2,3-triphenylcyclopropenyl azide (1, R = Ph)." The physical and spectral (IR and UV) properties of 2 were consistent with the assigned structure, and the presence of three contiguous carbon atoms was demonstrated by hydrolysis experiments, which resulted in formation of 1,2,3-triphenyI-butane-l,3-dione. Photolysis of 2 gave a mixture of nitrogen, benzo-nitriie, and diphenylacetylene. 

Disappearance of absorption band at 1630 cm was found for the multimethacrylate homopolymer (II) and copolymer (IV) of these two different multimonomers. IR spectra, NMR spectra and hydrolysis experiments lead to the following structures ... 

Most of the results obtained from the hydrolysis experiments were analyzed and represented as a function of R0, a reaction ordinate, previously defined and used (18). It is defined as... 

Such resolution could be readily optimized by use of an appropriate acyl group which reacts efficiently with the enzyme employed [29]. For example, the acetate prepared from monofluorinated a-phenetyl alcohol was hydrolyzed with lipase MY at 34% conversion to afford the product only with 26% . Enhancement of optical purity to 73% was observed when the corresponding isobutyrate was hydrolyzed. The best results were obtained for hydrolysis of the isobutyrate by lipase PS, which afforded the product in 82% at 47% hydrolysis. Experience has shown (see Table 3) that one of the best combinations was hydrolysis of acetate with lipase MY or isobutyrate with lipase PS [30]. 

Other model compound hydrolysis experiments confirmed this generic behavior. The dependence of hydrolysis on chemical structure of the model compounds was observed between the 4-FA imide compounds of SDA and ODPA. Under the same hydrolysis conditions, the highly electron-withdrawing sulfone group induced much more reaction of both the imide and the amic acid species than the ODPA analogue, as shown in Figure 17.14. Also, amines that... 

The standard enthalpies of formation of the acetylacetonate complexes of Al, Ga, Cr111 and Mnm have been determined by solution reaction calorimetry40-43 and the enthalpies of combustion of the Al, Ga and In tris(chelates) reported.44 Such data are relatively scarce in inorganic chemistry and quite valuable. For example, from solution calorimetric hydrolysis experiments on (MeCOCHC-OMe)2Pt, the Pt—O bond energy was found to be 183.1 kJ mol-1.45... 

The effect of the presence of dialkyl phosphoric acid was moderate, with an increase of the malonamide degradation probably by hydrolysis, as has been observed in specific hydrolysis experiments (71). 

Exchange of hydrogen and methyl groups between TV-trimethylborazine and hexamethylborazine was found to occur in the same temperature region as for the 5-trichloro system however, equilibrium was not reached. Hydrolysis experiments of pentamethylborazine isomers (293) showed that in each of the independent pyrolyses of the pentamethylborazine isomers, redistribution products were formed as a result of interchange of substituents only among like skeletal atoms. 

We hydrolyzed ATP and ADP in 1 N and 0.1 N HC1 and in buffered solutions at pH 4j nd 8 in which the hydrolysis medium was variously enriched in °0 to either 10% or 20%. To assess the isotopic enrichment of each such solution for use in the nucleotide hydrolysis experiments, we hydrolyzed PCI, in the solution, esterified the resultant phosphoric acid/inorganic phosphate (P.) by reaction with diazomethane, and determined the isotopic distribution of the trimethyl phosphate (TMPO) by mass spectrometry. The 1 N and 0.1 N HC1 hydrolyses were allowed to proceed for 45 min and 10 hr, respectively, at 70, insuring complete conversion of ATP into AMP + 2P. The pH 8 hydrolyses were allowed to proceed for 36 hr at 70 to a point (20-25% completion) at which the ratio of ADP to AMP established that 96% and 4%, respectively, of the P. released had arisen by the primary and secondary hydrolysis steps, namely, ATP ADP + P. and ADP " AMP + P. 0The pH 4 hydrolyses were allowed to proceed for 24 hr, also at 70, to 40% completion. 

To be able to study cellulose (Solka-floc) degradation without microbial conversion of the sugars formed, separate hydrolysis experiments were carried out in stirred flasks without cells. The conditions in these experiments were the same as during the corresponding fermentation... 

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