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Pepsin stability

Rodriguez et al. [68] studied the stability of niclosamide in artificial gastric and intestinal juices. The gastric juice contained sodium chloride and hydrochloric acid with or without pepsin. The intestinal juice contained sodium phosphate with or without pancreatin. Niclosamide was incubated with the juices at 37°C for 6 h. The remaining intact drug and its degradation products (2-chloro-4-nitroaniline, 5-chlorosalicylic acid) were extracted with chloroform/methanol (5 1) and determined by TLC and HPLC. The drug was stable in these media for at least for 6 h. [Pg.92]

Saaby S, Knudsen KR, Ladlow M, Ley SV (2005) The Use of a Continuous Flow-Reactor Employing a Mixed Flydrogen-Liquid Flow Stream for the Efficient Reduction of Imines to Amines. Chem Commun 23 2909-2911 Seebach D, Overhand M, Kilhnle FNM, Martinoni D, Oberer L, Hommel U, Widmer H (1996) Beta-Peptides Synthesis by Arndt-Eistert Homologation with Concomitant Peptide Coupling. Structure Determination by NMR and CD Spectroscopy and by X-ray Crystallography. Helical Secondary Structure of a Beta-Hexapeptide in Solution and its Stability Towards Pepsin. Helv Chim Acta 79 913-941... [Pg.20]

Tian SF, Toda S, Higashimo H and Matsumara S (1996) Glycation decreases the stability of the triple-helical strands of fibrous collagen against proteolytic degradation by pepsin in a specific temperature range. J Biochem 120, 1153-1162. [Pg.55]

We have approached this problem by studying the interactions between pepsin and ketones with structures based on that of pepstatin. Our strategy was to design ketones which would serve as pseudosubstrates, that is, be subject to the catalytic action of the enzyme, but only to the point of formation of a tetrahedral intermediate which, because of the increased stability of a C-C vs a C-N bond, would not break down to products. Such a stable tetrahedral intermediate would then, in principle, be amenable to study by the appropriate physical methods. appeared to be an ideal method since changes... [Pg.232]

Foaming Capacity and Stability. Pepsin digestion of soy protein has been proposed as a method for making a whipping protein for egg albumen replacement (42, 45) and for extenders for albumen in bakery and confectionery formulations (46). Puski... [Pg.289]

Pepsin and papain hydrolysates of rapeseed protein concentrate increased foam volumes and decreased drainage compared to the untreated control (36). Foaming properties could be further enhanced by adding a stabilizer such as carboxymethylcellulose. [Pg.289]

Pepsin is secreted as the inactive pepsinogen, which is activated by H+ ions at a pH below 5. Determination of its crystal structure revealed that in the proenzyme the N-terminal 44-residue peptide segment lies across the active site, blocking it.384 At low pH the salt bridges that stabilize the proenzyme are disrupted and the active site is opened up to substrates. [Pg.625]

Enzymes are protein catalysts of remarkable efficiency and specificity. Lipid, carbohydrate, nucleotide, or metal-containing prosthetic groups may be attached to these enzymes and serve as essential components of their catalyses by enhancing specificity and/or stability (8—13). Each enzyme has a specific temperature and pH range where it functions to its optimal capacity the optima for these proteins usually He between 37—47°C, and pH optima range from acidic, ie, 1.0 in the case of gastric pepsin, to alkaline, ie, 10.5 in the case of alkaline phosphatase. However, enzymes from extremely thermotolerant bacteria have become available these can function at or near the boiling point of water, and therapeutic use of these ultrastable proteins can be anticipated. [Pg.307]

Deglycosylation had no marked effect on the stability of the acid carboxypeptidase. Both native and deglycosylated enzymes were stable up to 50°C and active in the presence of 4 M urea after 24 h. The molecular structures of both enzymes were not impaired by pepsin at pH 2.5 (Figure 25). These two enzymes had similarly great resistance to peptic digestion after 24h. [Pg.225]

Fig. 5. Schematic representation of the collagen IV molecule, which consists of two al(IV) chains and one a2(IV) chain. The non-triple-helical interruptions of the triple helix are indicated by black bars. The cysteine residues (C) and lysine or hydroxylysine (K) residues putatively involved in intra- or intermolecular bonds are shown. CHO designates a N-giycosidically bound oligosaccharide chain. The subscript numerals indicate the number of residues in a distinct region, summarized for all three a-chains. P designates a main pepsin cleavage site. In interruption 13, the a2(IV) chain forms a 21-residue-long loop, stabilized by an interchain disulfide bridge. NCI, Noncollagenous domain 1 TH, triple-helical domain 7 S, carboxyl-terminal domain. Fig. 5. Schematic representation of the collagen IV molecule, which consists of two al(IV) chains and one a2(IV) chain. The non-triple-helical interruptions of the triple helix are indicated by black bars. The cysteine residues (C) and lysine or hydroxylysine (K) residues putatively involved in intra- or intermolecular bonds are shown. CHO designates a N-giycosidically bound oligosaccharide chain. The subscript numerals indicate the number of residues in a distinct region, summarized for all three a-chains. P designates a main pepsin cleavage site. In interruption 13, the a2(IV) chain forms a 21-residue-long loop, stabilized by an interchain disulfide bridge. NCI, Noncollagenous domain 1 TH, triple-helical domain 7 S, carboxyl-terminal domain.
Thermal Stability. The temperature optimum for arctic cod pepsin is approximately 32°C see Table III) and the enzyme is unstable when incubated at temperatures above 37°C see Figure 4) in contrast to porcine pepsin which has a temperature optimum of approximately 47°C and is unstable at temperatures above 50°C see Figure 4). Accordingly, there is a difference in thermal stability of approximately 13°C for the two enzymes. Similar differences in temperature optima were observed when Greenland cod and American smelt were compared with PP see Table III). These data are consistent with previous reports for intracellular enzymes and for crude preparations of pyloric caeca enzymes from other low-temperature-adapted organisms (42). [Pg.231]


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