Proteolytic hydrolysis

Since FPIAs are conducted as homogeneous immunoassays, they are susceptible to effects from endogenous fluorophores and from intersample variations. Such problems and others due to the sample matrix are largely avoided by sample dilutions of several hundredfold. Low-affinity, nonspecific binding of tracers to sample proteins, when present in sufficiently high concentrations, can result in a falsely elevated polarization signal. Interference from sample proteins can be eliminated when warranted, by proteolytic hydrolysis with pepsin.(46)... 

For the SAXS studies a CBH II sample was prepared by affinity chromatography from r. reesei QM 9414 to give the enzyme in a homogeneous form 27. In SDS-PAGE the protein had a size of 58 kDa and the isoelectric point was 4.9. Glycosy-lation was estimated as 8 to 18 % 36. The molar absorptivity at 280 nm was 75 000 M xm To obtain the core protein partial proteolytic hydrolysis with papain was per-... 

Enfuvirtide is a synthetic 36 -amino -acid peptide fusion inhibitor that blocks entry into the cell (Figure 49-4). Enfuvirtide, binds to the gp41 subunit of the viral envelope glycoprotein, preventing the conformational changes required for the fusion of the viral and cellular membranes. It has no activity against HIV-2. Enfuvirtide must be administered by subcutaneous injection. Metabolism appears to be by proteolytic hydrolysis without involvement of the CYP450 system. Elimination half-life is 3.8 hours. 

MS is the most important tool to study post-translational modifications including partial proteolytic hydrolysis, glycosylation, acylation, phosphorylation, cross-linking through disulfide bridges, etc of the proteins (Jonsson 2001). These modifications usually result in the functional complexity of proteins. 

The Lifetimes of Proteins Differ Abnormal Proteins Are Selectively Degraded Proteolytic Hydrolysis Occurs in Mammalian Lysosomes... 

Application and Principle This procedure is used to determine the proteolytic activity of papain, ficin, and bromelain. The assay is based on a 60-min proteolytic hydrolysis of a casein substrate at pH 6.0 and 40°. Unhydrolyzed substrate is precipitated with trichloroacetic acid and removed by filtration solubilized casein is then measured spectrophotometri-cally. 

Application and Principle This procedure is used to determine protease activity, expressed as PC units, of preparations derived from Bacillus subtilis var. and Bacillus licheniformis var. The assay is based on a 30-min proteolytic hydrolysis of casein at 37° and pH 7.0. Unhydrolyzed casein is removed by filtration, and the solubilized casein is determined spectro-photometrically. 

Product of proteolytic hydrolysis or digestion of proteins, also by acid hydrolysis. 

Hydrolyzed vegetable protein (HVP) is one of the earliest known forms of thermal reaction or process flavors (7,2). HVPs can been produced by acid (HCl) or enzyme (proteolytic) hydrolysis of a protein source (usually of plant origin) to form principally amino acids (7,5-5), which, themselves, can impart taste (e.g. monosodium glutamate) or participate in subsequent thermal reactions, e.g. Maillard reaction, to form aroma compounds (6,7). Among the numerous process parameters involved in the production of HVP, the substrate or protein source material may have a great in5)act on the resulting amino acid profile and flavor characteristics of the final product (7,5). 

Proteolytic hydrolysis, ion-exchange HPLC coupled to ICP-MS detection... 

Proteolytic hydrolysis of peptide bonds results in fragmentation of the protein chain. It is well established that in dilute acids, aspartic acid (Asp) residues in proteins are hydrolyzed at a rate at least 100-fold faster than that of other peptide bonds because of the mechanism of the reaction. An additional hydrolysis reaction is the deamidation of the neutral residue of asparagine (Asn) and glutamine (Gin) side-chain linkages, forming the ionizable carboxylic acid residues aspartic acid (Asp) and glutamic acid (Glu) (Fig. 6.26a). This conversion may be considered primary sequence isomerization. 

With regard to the fate of the iodinated amino acids in the thyroid, the following concluraons have been reached. Monoiodotyrosine and diiodotyrosine do not leave the thyroid gland after proteolytic hydrolysis of thyroglobulin, but are enzymically deiodinated with the formation of iodide this iodide is available for re-utilization in hormone synthesis. Thyroxine and triiodothyronine are released into the circulation. 

It has already been shown that the conjugate is stable in the presence of plasma pro-teinases and cytocidal towards B-16 melanoma cells. During drug liberation two degradative processes proceed concurrently, proteolytic hydrolysis of the carrier and cleavage of the polymer-drug linkages. 

Lombard (Fr. Pat. 350,179, 1904) claims that acids act as stimulating agents in the enzymic hydrolysis of oils, and further that a simple method of obtaining the active product is to triturate oil cake with its own weight of water, allow the mixture to undergo spontaneous proteolytic hydrolysis at 40° C. for eight days, and then filter, the filtrate obtained being used in place of water in the enzymic process. 

Two preliminary operations are necessary (o) hydrolysis, and (5) extraction of amino acids freed by hydrolysis. Chemical treatments, still used in many laboratories, are to be avoided because they lead to deiodi-nation which can be quite extensive in some cases (40,62). Hydrolysis by proteolytic enzymes is actually the best method (40). Proteolytic hydrolysis involves small losses of iodinated amino acids because it is never complete, but it has the great advantage of avoiding formation of partially deiodinated substances. Inorganic acids cause deiodination which is much more extensive than that produced by alkaline reagents. 

Enzymes, like other cellular proteins, are completely degraded to their constituent amino acids via the proteolytic sequence. There is no evidence that peptides which might occur as breakdown products can be utilized for the synthesis of the same or different proteins—another way of stating that protein degradation and protein synthesis do not share any intermediates. However, this does not mean that proteolytic cleavage necessarily leads to loss of function, nor the converse that activity is always retained unless proteolytic hydrolysis has occurred. 

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