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Pepsin enzymatic hydrolysis

Enzymatic hydrolysis Increased the soluble protein, compared to the respective controls (Figure 13). Approximate threefold Increases were noted after pepsin digestion, fourfold after bromelain, and twofold after trypsin. These levels of protein solubility were evident after only 10 min of enzyme treatment. Further digestion times did not significantly Increase the amount of soluble protein. [Pg.24]

Many workers have studied the influence of enzymatic hydrolysis on the functional properties of various food proteins, and much of this work has recently been reviewed by Richardson (2). However, there seem to be very few reports which quantitatively relate functionality to parameters which characterize the protein hydrolysates per se (e.g. molecular weight). Ricks et al. (3 ) examined the solubility and taste of a number of pure proteins (denatured pepsin, lactoblobulin, a-Sj -, K-, and 8-casein) hydrolysed with... [Pg.125]

One of the earliest suggestions that total enzymatic hydrolysis was possible came from the studies of Frankel (1916), who showed that over 90 % of the bonds in several proteins could be broken when proteolysis with pepsin, trypsin, and chymotrypsin was followed by prolonged hydrolysis with the erepsin preparation of Cohnheim (1901). The recognition in later years of several peptidases in intestinal exti acts which will specifically act upon bonds that are not susceptible to the endopoptidases (Bcrg-mann, 1942) probably accounts for these obseiwations. The specific peptidases such as prolidase, iminodipeptidase (prolinase), glycylglycine dipeptidase, tripeptidase, and leucine aminopeptidase, whi( h are present in mucosa, attack many of the bonds that resist the action of endopoptidases. [Pg.90]

Table XVI gives a partial list of native proteins that have been hydrolyzed with proteolytic enzymes. A discussion of the interpretation of each example listed is beyond the scope of this review, but a few comments concerning certain features of proteolysis are ivarranted. The mechanism of enzymatic hydrolysis of native proteins was studied in detail by Tiselius and Eriksson-Quensel (1939), who examined the action of pepsin on ovalbumin. Two mechanisms of proteolysis were considered by these workers. In the first mechanism the enzyme hydrolyzes all susceptible peptide bonds in one substrate molecule before hydrolysis of a second molecule begins. This type of mechanism has been described by Lmderstrpm-Lang (1952) as the all or none type. In the second mechanism, the enzyme hydrolyzes the single, most susceptible bond in all substrate molecules before hydrolysis of other bonds occurs. This mechanism is called the zipper type. Hydrolysis of a protein can proceed by either of the two mechanisms or by a mechanism which has features of both types. General aspects of the problem have been reviewed and theoretical equations which describe the kinetics of ea( h mechanism have been derived (Linderstr0m-Lang, 1952, 1953). Table XVI gives a partial list of native proteins that have been hydrolyzed with proteolytic enzymes. A discussion of the interpretation of each example listed is beyond the scope of this review, but a few comments concerning certain features of proteolysis are ivarranted. The mechanism of enzymatic hydrolysis of native proteins was studied in detail by Tiselius and Eriksson-Quensel (1939), who examined the action of pepsin on ovalbumin. Two mechanisms of proteolysis were considered by these workers. In the first mechanism the enzyme hydrolyzes all susceptible peptide bonds in one substrate molecule before hydrolysis of a second molecule begins. This type of mechanism has been described by Lmderstrpm-Lang (1952) as the all or none type. In the second mechanism, the enzyme hydrolyzes the single, most susceptible bond in all substrate molecules before hydrolysis of other bonds occurs. This mechanism is called the zipper type. Hydrolysis of a protein can proceed by either of the two mechanisms or by a mechanism which has features of both types. General aspects of the problem have been reviewed and theoretical equations which describe the kinetics of ea( h mechanism have been derived (Linderstr0m-Lang, 1952, 1953).
Furthermore, enzymatic hydrolysis of model isopeptides N -oligo(L-methionyl)-l-lysine from Bio-beads13031 by pepsin, chymotrypsin, cathepsin C (dipeptidyl peptidase IV) and intestinal aminopeptidase N was investigated using high-performance liquid chromatography to identify and quantify the hydrolysis products 3041. [Pg.1399]

One of the current approaches to the improvement of the functional properties of proteins is enzymatic hydrolysis [148], The emulsifying ability of soy protein isolate can be increased by treatment with neutral fungal protease however, this treatment decreases emulsion stability [163], Partial hydrolysis of fish protein concentrate improves both emulsification and stability [164]. On the other hand, treatment of whey protein concentrate with pepsin, pronase, and pro-lase leads to a decrease in emulsification ability, suggesting that there... [Pg.27]

It is not always possible to apply enzymatic hydrolysis directly to proteins as they are in the native form. Native, globular proteins (e.g., from soy, corn, almond) or fibrous insoluble proteins (e.g., collagen, keratins, elastin) are generally resistant to proteolysis this is generally explained by the compact tertiary structure of the protein that protects most of the peptide bonds. In the denatured, unfolded form the peptide bonds are exposed and available for enzymatic cleavage. As native proteins in aqueous solution are in dynamic equilibrium with a number of more or less distorted forms, part of which can be considered denatured and thereby accessible to enzyme attack, the initial break of a few peptide bonds can destabilize the protein molecule and cause irreversible unfolding in some cases (e.g., hydrolysis of egg albumin by pepsin) this mechanism allows the protease to perform the hydrolysis to a remarkable extent. More frequently, especially when covalent bonds (disulfide bonds) stabilize the native form of the protein, a preliminary partial or extended denaturation is needed to make enzymatic hydrolysis possible this is normally achieved by heating or chemical attack, or a combination of the two. [Pg.423]

The effect of the side chains of substrate residues not directly adjacent to the sensitive bond has been demonstrated in the following experiments. It was shown that, in the substrate AIa-Phe(N02)-Ala-APM, the bond Phe(N02)-Ala was only very slowly hydrolyzed by pepsin however, when the tripeptide Z-Leu-Ala-Ser-OH, which is not susceptible to enzymatic hydrolysis, was included in the hydrolysis solution, the rate of the substrate hydrolysis increased sharply (k t =0.48 min. 86 mM). Now, only the bond Ala-Phe(N02) was hydrolyzed. [Pg.182]

The synthesis of peptides by enzymatic hydrolysis of proteins was carried out with gas-vortex gradientless bioreactor of type BIOK-022. As enzymes were used pepsin and trypsin. Initial concentration of the protein substrates was 20% on weight. Temperature of the synthesis was 36-40 C. Synthesis was carried out during 1 h. Received peptides molecular weight was 800-1100 g/mol of titration method with formalin [2],... [Pg.28]

On-line hydrolysis of proteins catalyzed by trypsin or pepsin immobilized on monolithic silica beds was described by Kato et al. [86,195], whereas pepsin was encapsnlated into the silica-gel matrix (75 pm capillary column), without loss in enzymatic activity [195]. [Pg.36]

Enzymatic gelation of partially heat-denatured whey proteins by trypsin, papain, pronase, pepsin, and a preparation of Streptomyces griseus has been studied (Sato et al., 1995). Only peptic hydrolysate did not form a gel. The strength of the gel depended on the enzyme used and increased with increasing DH. Hydrolysis of whey protein concentrate with a glutamic acid specific protease from Bacillus licheniformis at pH 8 and 8% protein concentration has been shown to produce plastein aggregates (Budtz and Nielsen, 1992). The viscosity of the solution increased dramatically during hydrolysis and reached a maximum at 6% DH. Incubation of sodium caseinate with pepsin or papain resulted in a 55-77% reduction in the apparent viscosity (Hooker et al., 1982). [Pg.40]

The improvement of the whipping properties of enzymatically modified soy proteins and casein has already been of use in the baking industry. For example, Gunther (25) has patented a method for producing these products by pepsin hydrolysis. [Pg.138]

Molecular and enzymatic properties of serine carboxypeptidase (EC.3.4.1.6.1, CPase Top), isolated and refined from the common squid (Todarodes pacificus) liver, were studied. It was found that this enzyme reacts well at the C-terminal position of peptides having hydrophobic amino acids. Because of this property, it was anticipated that this enzyme would have the effect of eliminating bitterness of some peptides. This enzyme was used on bitter peptides prepared by hydrolysis of proteins with pepsin and trypsin. It was found that this CPase Top can eliminate bitter peptides prepared from soy protein and com gluten. [Pg.167]

At the beginning of this century, Sawyalow gave the name plastein to the insoluble material which appeared upon the incubation of a soluble mixture of enzymatic digestion products of fibrin with rennin (a pepsin-like enzyme from calf-stomach). This reaction, later observed also with enzymes different from rennin was studied more intensively in the 1920s by Wasteneys and Borsook [29] who showed that the products of peptic hydrolysis of egg albumin at pH 1.6 gradually formed a precipitate when the concentrated solution was incubated with pepsin at pH 4. [Pg.57]


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See also in sourсe #XX -- [ Pg.96 ]




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