Marine enzymes sources

With a-D-mannosidase preparations in a high state of purity, the addition of 0.01% of bovine albumin to the assay mixture may lead to a small increase in activity (not more than 10%), probably by lessening denaturation of the enzyme. a-D-Mannosidase from marine-molluscan sources is, to a considerable extent, activated in the assay by chloride ion, and, to some extent, by certain other anions. Maximum activity is displayed by the enzyme from the limpet, P. vulgata, when 0.1 M sodium chloride is included in the incubation mixture46 (see Section 11,5 p. 412). Chloride ion has no effect on the activity of jack-bean or rat-epididymal a-D-mannosidase. 

As antioxidant peptides are rarely present in marine invertebrates, they must be released from the parent protein by hydrolysis with enzymes. Various enzymes have been used to release peptides from muscle proteins. To date, different muscle proteins have been extracted, hydrolysed, and their antioxidant activities studied, which is among all invertebrate muscles the most similar to vertebrate skeletal muscle. Various studies have been conducted to investigate the antioxidant properties of hydrolysates or bioactive peptides from marine invertebrate sources like oysters... 

Nowadays, ACE inhibitory peptides have been isolated from meat, remaining muscle proteins, skin collagen and gelatin, bone, and internal organs of fishes such as Alaska pollack, bonito, tuna, salmon, shark, and sardine. Table 16.1 provides a partial summary of ACE inhibitory peptides derived from marine fish sources, their amino acid sequence, the enzyme used for hydrolysis, and IC50 values. The IC50 value is the concentration of peptide that inhibits 50% of ACE activity. 

TABLE 16.1 ACE inhibitory peptides derived from marine fish source, enzyme used for hydrolysis, amino acid sequence and IC50 value... 

Owing to its vast diversity of organisms and habitats, the marine world is a rich source of unique and valuable enzymes with potential applications in the food industry. Many marine-derived enzymes have physical, chemical, and/or catalytic properties unparalleled by their terrestrial counterparts. For example, most marine enzymes have cold-adapted properties that are useful in food and... 

Major sources of marine enzymes are by-products produced as a result of fish and shellfish processing such as the viscera, heads, skin, bones, exoskeletons, and shells. Specific sources for different marine enzymes are listed in Table I. Some novel sources of enzymes with unique properties include extremophiles and red algae. 

Fatty acids with odd numbers of carbon atoms are rare in mammals, but fairly common in plants and marine organisms. Humans and animals whose diets include these food sources metabolize odd-carbon fatty acids via the /3-oxida-tion pathway. The final product of /3-oxidation in this case is the 3-carbon pro-pionyl-CoA instead of acetyl-CoA. Three specialized enzymes then carry out the reactions that convert propionyl-CoA to succinyl-CoA, a TCA cycle intermediate. (Because propionyl-CoA is a degradation product of methionine, valine, and isoleucine, this sequence of reactions is also important in amino acid catabolism, as we shall see in Chapter 26.) The pathway involves an initial carboxylation at the a-carbon of propionyl-CoA to produce D-methylmalonyl-CoA (Figure 24.19). The reaction is catalyzed by a biotin-dependent enzyme, propionyl-CoA carboxylase. The mechanism involves ATP-driven carboxylation of biotin at Nj, followed by nucleophilic attack by the a-carbanion of propi-onyl-CoA in a stereo-specific manner. 

As already noted, MT has several sources such as lyase enzymes for L-methionine and S -methyl-L-cysteine. There are complex relationships between DMS, MT, and other VOSCs in the atmosphere, and in marine and terrestrial environments. The previously cited reviews should be consulted. 

Mollusks along with the crustaceans are also widely sought to participate in the world s consumption of marine food. Fermented marine food sauces such as blue mussel sauce and oyster sauce possess bioactive peptides which play a major role as Angiotensin I converting enzyme inhibitors that indirectly suppress hypertension (Wijesekara and Kim, 2010). Hence, the mollusk-derived proteins and other macromolecules are highly valuable to indicate these organisms as medicinally valuable food sources. 

Marine fishes are rich sources of structurally diverse bioactive compounds including polyunsaturated fatty acids, polysaccharides, minerals, vitamins, antioxidants, enzymes, and bioactive peptides (Kim et ah, 2008). Marine fish-derived ACE inhibitory peptides have been purified from enzymatic digestion of various fish materials from Alaska pollack (Nakajima et ah, 2009), bonito (Fujita et ah, 2000 Hideaki et ah, 1993 Yokoyama et ah,... 

Additional information <1, 3, 6, 18, 20, 21, 24> (<1, 3, 6> comparison of various enzymes of variou.s sources [37] <18, 20, 21> enzymes from marine fishes are less thermostable than that of carp, the latter being more labile than the rabbit enzyme [42] <24> shark muscle isozyme marginally more resistant to temperature inactivation than brain isozyme [46]) [37, 42, 46]... 

Marine organisms are a well-established source of unique and biologically active peptides. Complex cyclic peptides and depsipeptides have emerged as an important new class of metabolites present in extracts of marine organisms. Many of these peptides have been found to be extremely potent cytotoxic and /or enzyme inhibitors. 

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