Proteins papain

Proteins papain/cathepsin-L protease fonily (Mar spicules of Tethya aurantia, Porif. from California Shimizu 1998 Land kidney of Mamm. and tropical fruits of Ang. MI). 

Papayas contain papain, an enzyme that is similar to the digestive juice pepsin. Because this enzyme breaks down protein, papain extract from papayas is marketed as a meat... 

Pennisetuin glaucum (pearl millet) (Poaceae) [seed] Pennisetum Cysteine PI (24 kDa 3 Cys antifungal protein) Papain [182]... 

Industrial Uses. Papain is used in the leather industry to prepare the sides for tanning. Its proteolytic action removes some of the undesirable proteins which adhere to the hide and thus facilitates the subsequent tanning process. In the textile industry, the treatment of wool fibers with papain has been found to reduce the shrinkage from laundering. This appears to be caused by the abihty of the enzyme to destroy the elastic properties of wool protein. Because of its digestive action on protein, papain is used as a spot remover in the laundry and dry cleaning business. 

Procedure 3 papain, leucine aminopeptidase, prolidase This early procedure for enzymic hydrolysis of proteins was reported by Hill and Schmidt (1962) to be successful for hydrolysis of several proteins. Papain was found to be superior to subtilisin or a combination of trypsin and chymotrypsin for the initial hydrolysis. The method might be improved if aminopeptidase M (discovered after the method was developed) is used in place of the leucine aminopeptidase, but to our knowledge this has not been tested. The problem with diketo-piperazine formation from X-Pro dipeptides in aminopeptidase M hydrolysates of peptides (see above) may make this substitution less desirable than it would seem at first. 

Pish protein concentrate and soy protein concentrate have been used to prepare a low phenylalanine, high tyrosine peptide for use with phenylketonuria patients (150). The process includes pepsin hydrolysis at pH 1.5 ptonase hydrolysis at pH 6.5 to Hberate aromatic amino acids gel filtration on Sephadex G-15 to remove aromatic amino acids incubation with papain and ethyl esters of L-tyrosine and L-tryptophan, ie, plastein synthesis and ultrafiltration (qv). The plastein has a bland taste and odor and does not contain free amino acids. Yields of 69.3 and 60.9% from PPG and soy protein concentrate, respectively, have been attained. 

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. 

Different enzymes have different specificities. Some, such as amylase, are specific for a single substrate, but others operate on a range of substrates. Papain, for instance, a globular protein of 212 amino acids isolated from papaya fruit, catalyzes the hydrolysis of many kinds of peptide bonds. In fact, it s this ability to hydrolyze peptide bonds that makes papain useful as a meat tenderizer and a cleaner for contact lenses. 

Next we evaluate the PDLD + EVB surface for the enzymatic reaction using eq. (5.17). The resulting surface is shown in Fig. 5.6. As seen from the ligure, the protein can reduce Aby stabilizing the ionic state more than water. In fact, in the specific case of papain the protein inverts the stabilization of the covalent and ionic states relative to their order in solution. 

Page, M. I., and Jencks, W. P., entropic hypothesis of enzyme catalysis, 224-225 Papain, Cys-His proton transfer in, 140-143 Pauling, Linus, view of enzyme catalysis, 208 PDLD model, see Protein dipoles-Langevin dipoles model (PDLD)... 

Heavy meromyosin (HMM molecular mass about 340 kDa) is a soluble protein that has both a fibrous portion and a globular portion (Figure 49-4). It exhibits ATPase activity and binds to F-actin. Digestion of HMM with papain generates two subfragments, S-1 and S-2. The S-2 fragment is fibrous in character, has no ATPase activity, and does not bind to F-actin. 

Because of their very complex chemical structures and heterogeneity, melanins are difficult to extract, separate, and characterize from tissues. Eumelanins are insoluble in water and organic solvents. They can be extracted from tissues with strong chemicals that are capable of removing lipids, proteins, and other tissue components but also lead to the formation of degradation products. Enzymatic procedures were developed for the isolation of eumelanins from mammalian hair and irises. The first step is sequential digestion with protease, proteinase K, and papaine in the presence... 

Adams, G.E. and Redpath, J.L. (1974). Selective free-radical reactions with proteins and enzymes pulse radiolysis and inactivation studies on papain. Int. J. Badiat. Biol. 25, 129-136. 

Soya Proteins. Early attempts to make albumen substitutes from soya protein also ran into problems. A bean flavour tended to appear in the finished product. A solution to these problems has been found. Whipping agents based on enzyme modified soy proteins are now available. The advantage of enzymatic modification is that by appropriate choice of enzymes the protein can be modified in a very controlled way. Chemical treatment would be far less specific. In making these materials the manufacturer has control of the substrate and the enzyme, allowing the final product to be almost made to order. The substrates used are oil-free soy flakes or flour or soy protein concentrate or isolate. The enzymes to use are chosen from a combination of pepsin, papain, ficin, trypsin or bacterial proteases. The substrate will be treated with one or more enzymes under carefully controlled conditions. The finished product is then spray dried. 

Refinement takes place by adjusting the model to find closer agreement between the calculated and observed structure factors. For proteins the refinements can yield R-factors in the range of 10-20%. An example taken from reference 10 is instructive. In a refinement of a papain crystal at 1.65-A resolution, 25,000 independent X-ray reflections were measured. Parameters to be refined were the positional parameters (x, y, and z) and one isotropic temperature factor parameter... 

N-Nitrosamines have been shown to be inhibitors of cysteine-containing enzymes. For example, dephostatin and other N-methyl-N-nitrosoanilines (1) were found to be inhibitors of the protein tyrosin phosphatases, papain and caspase [90,91]. Inhibition results from the S-nitrosation of the critical cysteine residues in the active sites of the enzymes by the nitrosamines. Compounds 6 and 7 have been found to inhibit thrombus formation in arterioles and venules of rats [92], while N-nitrosamide 9 exhibited vasodilation and mutagenicity as a result of NO release [93]. 

A family of 100 hybridoma antibodies can typically provide 20 tight binders and these need to be assayed for catalysis. At this stage in the production of an abzyme, the benefit of a sensitive, direct screen for product formation comes into its own. Following identification of a successful catalyst, the antibody is usually recloned to ensure purity and stabilization of the clone, then protein is produced in larger amount (—10 mg) and used for determination of the kinetics and mechanism of the catalysed process by classical biochemistry. Digestion of such protein with trypsin or papain provides fragment antibodies, Fabs, that contain only the attenuated upper limbs of the intact IgG (Fig. 1). It is these components that have been crystallized, in some... 

Among multitryptophan proteins emitting light around 330 nm, we have observed the largest red-edge effect (estimated from the difference between the maxima of the fluorescence spectra obtained at 290- and 305-nm excitation) for papain in the active and inactive forms (13 and 10 nm, respectively). Large shifts were also observed for rabbit muscle asparagyl- and valyl-RNA synthetases (8 nm). For rabbit aldolase A, the observed shift was 6 nm, for skeletal muscle myosin, 4.5 nm, for chymotrypsin, 2.5 nm, and for carbonic... 

During the last ten years, it has become apparent that calcium-dependent papain-like peptidases called calpains (EC 3.4.22.17) represent an important intracellular nonlysosomal enzyme system [35][36], These enzymes show limited proteolytic activity at neutral pH and are present in virtually every eukaryotic cell type. They have been found to function in specific proteolytic events that alter intracellular metabolism and structure, rather than in general turnover of intracellular proteins. Calpains are composed of two nonidentical subunits, each of which contains functional calcium-binding sites. Two types of calpains, i.e., /i-calpain and m-calpain (formerly calpain I and calpain II, respectively), have been identified that differ in their Ca2+ requirement for activation. The activity of calpains is regulated by intracellular Ca2+ levels. At elevated cytoplasmic calcium concentrations, the precursor procal-pain associates with the inner surface of the cell membrane. This interaction seems to trigger autoproteolysis of procalpain, and active calpain is released into the cytoplasm [37]. 

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