Enzyme papain

Figure 1S.6 Enzymatic cleavage of immunoglobulin IgG. The enzyme papain splits the molecule in the hinge region, yielding two Fab fragments and one Fc fragment.

As depicted in Figure 50-8, digestion of an immunoglobulin by the enzyme papain produces two antigen-binding fragments (Fab) and one crystallizable fragment (Fc), which is responsible for functions of im-... 

The first and most extensively examined system was the hydrolytic enzyme papain. A variety of isomeric a-bromoacetylisoalloxazines were used to selectively tether a flavin moiety to the active site cysteine residue. Different isomeric linkages were proposed to allow orientations of the flavin relative to the substrate binding site which would favor reactions with a bound substrate [65]. 

A coating bearing one enzyme (papain) is produced on the surface of a glass pH electrode by the method previously introduced (co-crosslinking). The papain reaction decreases the pH, and the pH-activity variation gives an autocatalytic effect for pH values greater than the optimum under zero-order kinetics for the substrate (benzoyl arginine ethyl ester) the pH inside the membrane is studied as a function of the pH in the bulk solution in which the electrode is immersed. A hysteresis effect is observed and the enzyme reaction rate depends not only on the metabolite concentrations, but also on the history of the system. 

Exercise 25-30 The proteolytic enzyme, papain, differs from chymotrypsin in having cysteine, or a labile derivative thereof, as part of its active site. The enzyme is deactivated by substances that form complexes with, or react with, —SH groups and the activity is restored by reactions expected to regenerate an —SH group. Work out a schematic mechanism for cleavage of a peptide chain with papain that involves acylation of the critical —SH group of papain. 

Cysteine proteases are a class of enzymes that have been widely studied over the years. The overall principles of substrate recognition, catalysis, and inhibition are now reasonably well documented. This enzyme class includes the plant proteases such as papain, actinidin, and bromelain, and several mammalian lysosomal cathe-psins. By far the majority of the literature reports dealing with cysteine proteases describe results obtained with the enzyme papain, because it is considered to be the archetype of this enzyme class. 

Figure 1. A simplified representation of the possible process for the papain-catalyzed hydrolysis and aminolysis E, enzyme (papain) S, substrate (protein) ES, Michaelis complex ES, peptidyl enzyme N, nucleophile (amino acid ester) P and P2, products formed from S by hydrolysis ...

Azaserine labeled enzyme Papain, pronase, aminopeptidase C -labeled azaserinepeptide Dawid ei al. (1963)... 

The flesh of the papaya fruit is orange-yellow and edible. Papaya fruits can be eaten fresh, boiled, preserved, or reduced to a juice. Other products can be created from the milky latex of the papaya including a base for chewing gum and an extract containing the enzyme papain. Papain is used to tenderize tough meats by predigesting some of their proteins. 

Treatment with cither of two enzymes, papain or pepsin. 

Milne, J. and Brand, S. (1975). Occupational asthma after inhalation of dust of the proteolytic enzyme papain. Br. J. Ind. Med. 32, 302-307. 

Saponins, glucosinate, polyketide, alkaloids, protelytic enzyme papain, chymopapain, flavonols. 

Amino acid residues within the hinge region of the heavy chains are accessible to proteolytic enzymes. Cleavage within this region by the enzyme papain results in the formation of three products one consists of the CH2 and... 

PINEAPPLE, Ananas comosm (L). Merr., Family Bromdiaceae and PAPAYA, Carica papaya, L., Family Carica-ceae are two plants which contain proteolytic enzymes bromelain in pineapple and papain in unripe papaya fruits. These two are proteases and can degrade protein in meat in cases where there is a deficiency of digestive enzymes. Papain is widely used as a meat tenderiser as are ficin from Ficus glabra and the bromelains. It is also used in more purified form (Chymopapain) in chemonucleolysis to shrink ruptured or slipped vertebral discs. 

However, the closely related amino acid 133 was not a substrate for either lipase (from pigs or Candida) but could be resolved with the proteolytic enzyme papain. This acted as an esterase, hydrolysing the methyl ester rather than the amide. Note that this kinetic resolution produces a single enantiomer of the carboxylic acid rather than the alcohol and that separation of 134 from 133 is very easy as the free acid can be extracted from organic solvents by aqueous base in which it is soluble as the anion. 

In 1937, Balls et al. [4] purified one of the proteolytic fractions and called their crystalline enzyme papain. This was an unfortunate choice, since the name papain is also used for the crude papaya latex containing multiple enzymes. In 1939, Lineweaver and Balls published a refinement of the isolation method, and they also reported the presence in the papaya latex of another proteinase with a higher ratio of milk-clotting to hemoglobin-digesting activity than papain [5], In 1941 Jansen and Balls presented a description of a second proteolytic enzyme [6]... 

Harrison MJ, Burton NA, Hillier IH. Catalytic mechanism of the enzyme papain predictions with a hybrid Quantum Mechanical/Molecular Mechanical potential. J Am Chem Soc 1997 119 12285-12291. 

Fig. 2.1 The antibody. An IgG antibody has a single constant region (white) with the Fc portion and the species-specific antigens. The variable region (gray) contains the Fab portion that binds the epitope portion of the antigen. The small protein, only in the variable region, is known as the light chain the large protein that is part of the constant and variable region is the heavy chain. The IgG can be digested by the protease enzyme, papain, into an Fc end (constant end) and a Fab end (variable end)...

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