Hydrolysed proteins

Plasteins ate formed from soy protein hydrolysates with a variety of microbial proteases (149). Preferred conditions for hydrolysis and synthesis ate obtained with an enzyme-to-substrate ratio of 1 100, and a temperature of 37°C for 24—72 h. A substrate concentration of 30 wt %, 80% hydrolyzed, gives an 80% net yield of plastein from the synthesis reaction. However, these results ate based on a 1% protein solution used in the hydrolysis step this would be too low for an economical process (see Microbial transformations). 

Pish silage prepared by autolysis of rainbow trout viscera waste was investigated as a substrate for the plastein reaction using pepsin (pH 5.0), papain (pH 6—7), and chymotrypsin (pH 8.0) at 37°C for 24 h (152). Precipitation with ethanol was the preferred recovery method. Concentration of the protein hydrolysate by open-pan evaporation at 60°C gave equivalent yields and color of the final plastein to those of the freeze-dried hydrolysate. 

The sulfur amino acid content of soy protein can be enhanced by preparing plasteins from soy protein hydrolysate and sources of methionine or cystine, such as ovalbumin hydrolysate (plastein AB), wool keratin hydrolysate (plastein AC), or L-methionine ethyl ester [3082-77-7] (alkaU saponified plastein) (153). Typical PER values for a 1 2 mixture of plastein AC and soybean, and a 1 3 mixture of alkah-saponified plastein and soybean protein, were 2.86 and 3.38, respectively, as compared with 1.28 for the soy protein hydrolysate and 2.40 for casein. 

Baits include mixtures of toxicant, usually at l ndash 5%, with a carrier especially attractive to the insect pest. Carriers include sugar for the houseflies, protein hydrolysates for fmit flies, bran for grasshoppers, and honey, chocolate, or peanut butter for ants. 

In traditional cooking of proteinaceous foods, the fundamental difference between Western and Oriental cultures is that the former cooks proteins with unseasoned fats and the latter cooks with many kinds of traditional seasonings that have tastes of amino acids. Western cultures have some traditional foods with amino acid taste such as cheese. Protein hydrolysates are popular as seasonings (225). 

In Parenteral and Enteral Nutrition. Amino acid transfusion has been widely used since early times to maintain basic nitrogen metaboHsm when proteinaceous food caimot be eaten. It was very difficult to prepare a pyrogen-free transfusion from protein hydrolysates. Since the advances in L-amino acid production, the crystalline L-amino acids have been used and the problem of pyrogen in transfusion has been solved. The formulation of amino acid transfusion has been extensively investigated, and a solution or mixture in which the ratio between essential and nonessential amino acid is 1 1, has been widespread clinically. Special amino acid mixtures (eg, branched chain amino acids-enriched solution) have been developed for the treatment of several diseases (93). 

Acylated Protein Hydrolysates. These surfactants are prepared by acylation of proteia hydrolysates with fatty acids or acid chlorides. The hydrolysates are variable ia composition, depending on the degree of hydrolysis. CoUagen from leather (qv) processiag is a common proteia source. Acylated proteia hydrolysates (Maypoa, by laotex Chemical Company) are mild surfactants recommended for personal-care products (see Cosmetics). 

Bone Cleaning. As an alternative to rendering, an en2ymatic process can be used to upgrade fresh bones to valuable products, eg, cleaned bone suitable for gelatin production and a meat protein hydrolysate for the food industry. This process is performed as a two-step en2yme process, ie, scrap meat recovery and bone cleaning. 

Amino acids protein hydrolysates, bacterial cultures, food, urine various... 

One method that combines the good chromatographic properties with improved limit of detection is the separation of isoindole derivatives of amino acids that may be detected fluorimetrically. This method may be applied to protein hydrolysates, and used in automated format in routine analyses [22]. 

The method described above is applicable to a wide range of samples for the determination of amino acids in different matrices. For example, the amino acid composition and distribution of single enantiomers has been determined in protein hydrolysates, orange juice (Fig. 7-11), yogurt and seawater [23]. 

Amino acids isolated from protein hydrolysates. 

One of the amino adds commonly found in protein hydrolysates is called cystine it has the following structure ... 

In analogy to the well-known condensation products of fatty acids with protein hydrolysates, a patent has also been initiated for the condensation products of ether carboxylic acids and protein hydrolysates [43]. They are made by converting the ether carboxylic acids with thionyl chloride (SOCl2) to the corresponding acid chlorides followed by the condensation with a protein hydrolysate. 

Nokihara K, Gerhardt J Development of an improved automated gas-chromatographic chiral analysis system application to non-natural amino acids and natural protein hydrolysates. Chirality 2001 13 431. 

Table 9.2 Derivatisation methods for the GC analysis of protein hydrolysates from paint samples...

Demmelmair, H. and Schmidt, H. L. (1993) Precise 813C determination in the range of natural abundance on amino acids from protein hydrolysates by gas chromatography isotope ratio mass spectrometry. Isotopenpraxis 29, 237 250. 

Infants treated before 1979 received protein hydrolysates containing high concentrations of phosphate which limited the concentration of calcium that could be used without causing precipitation. Beginning in 1979 crystalline amino acid solutions which contained less obligatory phosphate became available these allowed greater latitude in the concentrations of calcium and phosphate that could be achieved. The data in Table I suggest that the severity of demineralization and the incidence of fractures and rickets will decrease if more calcium is added to the parenteral alimentation solution. 

Two other reagents used in HPLC are 9-fluorenyl methoxycarbonyl chloride (FMOC) and phenylisothiocyanate (PITC). 9-fluorenyl methoxycarbonyl chloride is becoming increasingly popular in protein chemistry research because it reacts with secondary amines and also offers rapid analysis of protein hydrolysates. 

Despite the problems encountered in sample preparation, the chromatography of protein hydrolysate samples is straightforward and can give good resolution in a short time. 

The analysis time for protein hydrolysates is 85 min using standard columns. For extra high resolution a high-resolution lithium cation exchange column is recommended which achieves baseline separation of virtually all 40 amino acids (Fig. 1.3). 

In the development of the protein-fatty acid condensates it was possible to combine the renewable resources fatty acids (from vegetable oil) and protein, which can be obtained from both animal waste (leather) as well as from many plants, to construct a surfactant structure with a hydrophobic (fatty acid) and a hydrophilic (protein) part (Fig. 4.12). This was carried out by reacting protein hydrolysate with fatty acid chloride under Schotten-Baumann conditions using water as solvent. Products are obtained that have an excellent skin compatibility and, additionally, a good cleaning effect (particularly on the skin) and, in combination with other surfactants, lead to an increase in performance. For instance, even small additions of the acylated protein hydrolysate improve the skin compatibility. An... 

Example Mixture of amino acids obtained from protein hydrolysates are separated by this method and spots located by using Ninhydrin Reagent that forms a pink to purple product with amino acids. 

The complete identification of the amino acids which are essential in the diet is due to W.C. Rose (1938). His first attempts to replace casein with its constituents were unsuccessful because an essential amino acid component in the protein hydrolysate had been missed. After threonine had been isolated by him from casein and fibrin, and shown to be essential, Rose identified val, met, his, lys, phe, leu, ile, thr, and arg as... 

Although these experiments showed growth was possible using casein hydrolysate, Rose also demonstrated that when the amino acid mixture was used rather than the intact protein, additional calories had to be provided as fat plus carbohydrate, if nitrogen balance was to be maintained. It was later shown that the carbohydrate was needed to protect the free amino acids from oxidation in the intestinal epithelium in the course of absorption. Further, amino acids are poorly tolerated by mouth, causing vomiting and/or diarrhea. After World War II attempts to feed very emaciated prisoners in concentration camps with protein hydrolysates were unsuccessful. It was then recognized that osmotic effects from the amino acids were responsible for the unpleasant consequences. 

From 1951, Moore and Stein at the Rockefeller Institute refined the quantitative separation of amino acids on Dowex-50 which led to fully automated amino acid analyses. In early models two columns were needed one of 100 cm to separate most of the acidic and monobasic monocarboxylic acids between pH 3-11 and a short, 15 cm column for the basic amino acids which were eluted at pH <7. The columns operated above room temperature to give more rapid results, and the elution was monitored automatically by quantitative ninhydrin reactions. By the late 1950s a protein hydrolysate could be analyzed overnight. 

D. Duggan and S. Udenfriend, The spectrofluorometric determination of tryptophan in plasma and of tryptophan and tyrosine in protein hydrolysates, J. Biol. Chem. 223, 313-319 (1956). 

The development of chiral separation methods for dipeptides is of relevance for purity controls, for checking racemization processes in peptide syntheses, and for the investigation of peptide and protein hydrolysates. Since their introduction as chiral... 

Block, R. J. Amino acid analysis of protein hydrolysates, in A laboratory manual of analytical methods of protein chemistry". Vol. 2, 1 —57. Ed. P. Alexander u. R. J. Block, Pergamon Press, 1960. 

Tyrosine (Tyr or Y) (4-hydroxyphenylalanine ((5)-2-amino-3-(4-hydroxyphenyl)-propanoic acid)) is a polar, neutral, aromatic amino acid with the formula H00CCH(NH2)CH2C6H50H and is the precursor of thyroxin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and the pigment melanin. Being the precursor amino acid for the thyroid gland hormone thyroxin, a defect in this may result in hypothyroidism. Tyr is extremely soluble in water, a property that has proven useful in isolating this amino acid from protein hydrolysates. The occurrence of tyrosine- 0-sulfate as a constituent of human urine and fibrinogen has been reported. ... 

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