Enzymes ficin

Equation 4.24 has been experimentally tested using a carboxymethylcellulose stationary phase onto which the enzyme ficin (E.C.3.4.22.3) has been immobilized. Ficin catalyzes the hydrolysis of a variety of ester substrates, but the substrate N-benzoyl-L-arginine ethyl ester (BAEE) has been chosen for this series of experiments (Eq. 4.25) ... 

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. 

Plant Proteases. These include the well known proteases papain, bromelain and ficin. Most plant enzymes are available as comparatively unpurified powder extracts, although papain is notable for being available in a stabilized and purified liquid form. Prospects for increased supply of plant enzymes, in response to greater use in traditional applications or for new processes, depend on several factors. Tlie influence of cultivation conditions, growth cycle and climate requirements make new supplies long term projects. 

The greatest variety of industrial enzymes are presently derived from microbial sources, with a lesser diversity coming from plant and animal sources 34), Enzymes derived from plant sources and which are used extensively in the food industry include papain, bromelain, ficin, and amylases. Animal enzymes of economic importance include trypsins, lipases, and gastric proteases. 

In the course of investigations using 4-chloro-7-nitrobenzofurazan as a reactivity probe for identifying the active sites of a number of enzymes such as papain, ficin, and bromelain, the intermediacy of Meisenheimer adducts derived from direct attack of thiolate groups located in the protein has been assumed on the basis of the spectral changes accompanying the process of replacement of the chloro group.232,233... 

In enzymes, the most common nucleophilic groups that are functional in catalysis are the serine hydroxyl—which occurs in the serine proteases, cholinesterases, esterases, lipases, and alkaline phosphatases—and the cysteine thiol—which occurs in the thiol proteases (papain, ficin, and bromelain), in glyceraldehyde 3-phosphate dehydrogenase, etc. The imidazole of histidine usually functions as an acid-base catalyst and enhances the nucleophilicity of hydroxyl and thiol groups, but it sometimes acts as a nucleophile with the phos-phoryl group in phosphate transfer (Table 2.5). 

PROTEASE. A proteolytic enzyme that weakens or breaks the peptide linkages in proteins, They include some of the more widely known enzymes such as pepsin, trypsin, ficin, bromelm, papain, and rennin. Being water soluble they solubilize proteins and are commercially used for meat tendenzers, bread baking, and digestive aids. 

Enzyme Nomenclature. The number of enzymes known exceeds two thousand. A system of classification and nomenclature is required to identify them unambiguously. During the nineteenth century, it was the practice to identify enzymes by adding the suffix -in to the name of their source. Names such as papain, ficin, trypsin, pepsin, etc, are still in use. However, this system does not give any indication of the nature of the reaction catalyzed by the enzyme or the type of substrate involved. 

The iron complexes of both human serum transferrin and chicken ovo-transferrin were completely resistant to all proteolytic enzymes tested (7). The metal-free proteins, on the other hand, were rapidly hydrolyzed under similar conditions. Fig. 14 compares results with bovine a-chymo-trypsin. Other enzymes used with similar results were bovine trypsin, bacterial proteinase (Nagarse) and ficin (735). The weaker copper complex of chicken ovotransferrin was hydrolyzed, however, at a rate approx-... 

Source. Enzymes for food applications come from all three kingdoms plant, animal, and microbial. Traditionally used plant and animal enzymes are the plant proteases such as papain, ficin and bromelain, plant amylases from malt, and animal rennin which is used in cheese manufacture. Microbial cells are the usual and most promising future source of industrial enzymes. Estimates of the number of microorganisms in the world tested as potential sources of enzymes fall around 2% with only about 25 organisms, including a dozen or so fungi, currently used for industrial enzymes. 

Cysteine proteases are so called because of a critical cysteine involved (together with an adjacent histidine) in the catalytic mechanism. Cysteine proteases include papain-related proteases, calpain-related proteases and the caspases. Papain-like cysteine proteases include the plant enzymes actinidin, aleurain, bromelain, caricain, chymopapain, ficin and papain and the lysosomal cathepsins B, C, H, K, L and S. Cathepsin C is multimeric (MW -200,000), but the other papain-related proteases are monomeric with MWs of about 20,000-35,000. While cathepsin C is a dipeptidyl aminopeptidase, the other enzymes are endopeptidases. Cathepsin B is an endopeptidase and a dipeptidyl carboxypeptidase. Cathepsin H is an endopeptidase and an aminopeptidase. In higher animals, cathepsin B generates peptides from antigens for presentation to T cells by the major histocompatibility... 

It has already been remarked that most enzymes with elastolytic activity have proved to be proteinases with a wide peptide-bond specificity. Thus papain, bromelin, and ficin have a similarly broad hydrolytic action and are all active elastolytic enzymes. Sanger et al. (1955) found that the oxidized A chain of insulin was hydrolyzed in a variety of positions by either crude papain or activated mercuripapain. There were five major... 

Among the proteolytic enzymes, the plant proteases are the most widely used in the food industry. Most of the plant proteases which have been studied are characterized by a free sulfhydryl group which is essential for their activity. The most important of these so-called sulfhydryl or thiol proteases are papain, ficin, and bromelain. Since the literature on these enzymes has been the subject of several recent reviews (i, 2, 3, 4), major emphasis is placed in this presentation on the use of these enzymes in the food industry. Some of the more recent developments relating to the structure and function of the sulfhydryl proteases are discussed. 

Inhibition. Since papain, ficin, and bromelain are all enzymes whose activity depends on a free SH group, it is to be expected that all thiol reagents act as inhibitors. Thus, a-halogen acids or amides and N-ethyl-maleimide irreversibly inhibit the thiol proteases. Heavy metal ions and organic mercurial salts inhibit in a fashion that can be reversed by low molecular weight thiols, particularly in the presence of EDTA which... 

In recent years a number of authors have reported the specific enzymatic cleavage of the cross-links in collagen (Barkin and Oneson, 1961 High-berger, 1961b Kiihn et al., 1961 Nishihara, 1962 Schmitt, 1963 Kiihn et al., 1963a Rubin et al., 1963 Hafter and Hermann, 1963). The enzymes used include pepsin, ficin, trypsin, and unpurified pancreas extracts of these pepsin is the most effective. As pepsin has no esterase or other nonproteolytic activity it appears that the cross-links include, even if they are not entirely, sections of peptide chains. 

Structural details of various blood group substances were revealed by partial hydrolysis, chromatography, and results of periodate oxidation, treatment with various enzymes such as ficin (M50), and acetolysis (Mil, M12, M15-M17, M19-M21, Y4, Y5). They are well described in various reviews on carbohydrates (K16, S39) and blood group substances (Kl, M49, M50). 

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