Acyl hydrolyzed protein

Two further compounds are briefly discussed here. Tetrachloroethylene administered to animals yielded 2,2,2-trichloroacetic acid (10.95, Fig. 10.23) as the only chlorinated metabolite [13]. These findings provided the first evidence that tetrachloroethylene is oxidized by cytochrome P450 to its epoxide (10.94), which rearranges by Cl migration to 2,2,2-trichloroacetyl chloride (Fig. 10.23). The latter hydrolyzes to 2,2,2-trichloroacetic acid (10.95), but also acylates tissue proteins, a reaction of unclear toxicological significance. In vitro investigations of tetrachloroethylene oxide (2,2,3,3-tetrachlo-rooxirane, 10.94) further showed that it hydrolyzes to the vicinal diol (10.96... 

Chymotrypsin is not, as enzymes go, very specific in its action it hydrolyzes proteins, peptides, simple amides, and esters alike. There is one structural requirement, nevertheless a relatively non-polar group in the acyl moiety of the substrate,... 

The answer is e. (Murray, pp 230-267. Scriver, pp 2297-2326. Sack, pp 121-138. Wilson, pp 287-320.) The fatty acid synthase complex of mammals is composed of two identical subunits. Each of the subunits is a multienzyme complex of seven enzymes and the acyl carrier protein component. All the components are covalently linked together thus, all the components are on a single polypeptide chain, which functions in the presence of another identical polypeptide chain. Each cycle of fatty acid synthesis employs the acyl carrier protein and six enzymes acetyl transferase, malonyl transferase, p-ketoacyl synthase, p-ketoacyl reductase, dehydratase, and enoyl reductase. When the final fatty acid length is reached (usually C16), thioesterase hydrolyzes the fatty acid off of the synthase complex. 

Acylated Polypeptides (From partially hydrolyzed protein from scrap leather and other waste protein.) Used in hair preparations and shampoos, alkaline cleaning preparations, wax strippers. Good detergency and resistance to hard water. 

Although a large number of studies have been conducted on adsorption of native proteins at solid-liquid interfaces, the modified proteins have not been studied systematically to the best of our knowledge. However, there are several commercial products that are based on condensation reactions between acyl chloride and hydrolyzed proteins, which are used for cosmetic hair products [821 and are obviously based on the ability of the modified proteins to adsorb at the hair-water interface. These products are based on electrostatic adsorption, which leads to the presence of hydrophobic moieties on the hair fibers, and hence a conditioning effect is observed. 

Protein hydrolysate. See Hydrolyzed collagen Protein hydrolysates. See Hydrolyzed protein Protein hydrolysates, casein, coco acyl derive., potassium salts. See Potassium cocoyl hydrolyzed casein... 

Condensation of hydrolyzed proteins with fatty acid groups determines reduction of the skin and eye compatibility, resulting from the increase of their amphiphilic character the skin/eye tolerability of acylated proteins is reported to increase with the average length of the peptide moiety (127). Quaternized derivatives are generally less compatible than fatty acid condensates (128). The irritation potential of protein-surfactant complexes is intermediate between those of the parent protein and the pure tenside. 

Leek extracts possess at least two acyl-acyl carrier protein (ACP) thioesterase (acyl-ACP hydrolase) activities. One is the well characterized oleoyl-ACP thioesterase (OTE) and the other is a stearoyl-ACP thioesterase (STE) with high specificity for its substrate. The relative activities of these two thioesterases differed between mesophyll and epidermis, STE has been separated from OTE and purified to near homogeneity by a seven-step procedure that included an ACP-affinity column. The purified STE was found to primarily hydrolyze stearoyl-ACP. 

In contrast, with penicillins, cephalosporins, and monobactams where the substituents are cis to each other across the C3 - C4 bond, clockwise rotation can occur without conflict with protein side chains, and will leave the path open for the water molecule to attack and hydrolyze the ester group in B (Scheme 10). Thus, czs-substituted monobactam, as well as penicillins and cephalosporins are rapidly hydrolyzed by class C enzymes (Scheme 10). If this rotation could be prevented by a suitable structural modification, the access of the water molecule to the ester bond will be blocked, which would result in increased stability of the acyl-enzyme complex. 

This enzyme [EC 3.4.16.4], also known as serine-type D-alanyl-D-alanine carboxypeptidase, catalyzes the hydrolysis of D-alanyl-D-alanine to yield two D-alanine. This enzyme comprises a group of membrane-bound, bacterial enzymes of the peptidase family Sll. They are distinct from the zinc D-alanyl-D-alanine carboxypeptidase [EC 3.4.17.14]. The enzyme also hydrolyzes the D-alanyl-D-alanine peptide bond in the polypeptide of the cell wall. In addition, the enzyme will also catalyze the transpeptidation of peptidyl-alanyl moieties that are A-acetyl-substituents of D-alanine. The protein is inhibited by j8-lactam antibiotics, which acylate the active-site seryl residue. 

This endopeptidase [EC 3.4.22.2], a member of the Cl peptidase family hydrolyzes peptide bonds in proteins, exhibiting a broad specificity for those bonds. There is a preference for an amino acyl residue bearing a large hydrophobic side chain at the P2 position and the enzyme does not accept a valyl residue at Pi. 

Papain is a protein-hydrolyzing (proteolytic) enzyme with an -SH group and an imidazole group at the active site. Write a reasonable structure for a "tetrahedral intermediate" that would be expected to arise during formation of an acyl enzyme intermediate. 

The splicing mechanism, which is illustrated for this intein, is shown in the accompanying equations.1 1 Step a is an N —> S or N —> O acyl shift. This is followed by transesterification (step b) which involves either thioesters (as illustrated) or oxygen esters. Formation of a succinmide intermediate (step c) releases the intein and the spliced protein. The latter must undergo an S—> N or O—> N acyl shift (step d), and the succinimide in the extein must be hydrolyzed to complete the process. 

Maleic acid is a linear four-carbon molecule with carboxylate groups on both ends and a double bond between the central carbon atoms. The anhydride of maleic acid is a cyclic molecule containing five atoms. Although the reactivity of maleic anhydride is similar to that of other cyclic anhydrides, the products of maleylation are much more unstable toward hydrolysis, and the site of unsaturation lends itself to additional side reactions. Acylation products of amino groups with maleic anhydride are stable at neutral pH and above, but they readily hydrolyze at acid pH values around 3.5 (Buder et al., 1967). Maleylation of sulfhydryls and the phenolate of tyrosine are even more sensitive to hydrolysis. Thus, maleic anhydride is an excellent reversible blocker of amino groups to mask them temporarily from reactivity while another reaction is being done. For additional information and a protocol for the modification of proteins with this reagent, see Section 4.2. 

Chymotrypsin, a serine endopeptidase, most readily reacts at the carboxyl group of the aromatic amino acid residue of proteins and polypeptides (or N-acyl aromatic amino acid esters) to form first a tetrahedral intermediate which then collapses into an acyl-enzyme (7+ 8- I>). The acyl-enzyme is then hydrolyzed by water to furnish the M-acylated aromatic amino acid again through the formation of a tetrahedral intermediate (JO Jl -> J2) (1-4). 

Limiting essential amino acids covalently attached to proteins by using activated amino acid derivatives can improve the nutritional quality and change the functional properties of proteins. The best chemical methods for incorporating amino acids into water-soluble proteins involve using car-bodiimides, N-hydroxysuccinimide esters of acylated amino acids, or N-carboxy-a-amino acid anhydrides. The last two methods can give up to 75% incorporation of the amount of amino acid derivative used. With the anhydride method, as many as 50 residues of methionine have been linked to the 12 lysine residues of casein. The newly formed peptide and isopeptide bonds are hydrolyzed readily by intestinal aminopeptidase, making the added amino acids and the lysine from the protein available nutritionally. 

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