Enzymes from fish and aquatic invertebrates and their application in the food industry

Marine Fish Proteins and Peptides for Cosmeceuticals: A Review

Marine fish provide a rich source of bioactive compounds such as proteins and peptides. The bioactive proteins and peptides derived from marine fish have gained enormous interest in nutraceutical, pharmaceutical, and cosmeceutical industries due to their broad spectrum of bioactivities, including antioxidant, antimicrobial, and anti-aging activities. Recently, the development of cosmeceuticals using marine fish-derived proteins and peptides obtained from chemical or enzymatical hydrolysis of fish processing by-products has increased rapidly owing to their activities in antioxidation and tissue regeneration. Marine fish-derived collagen has been utilized for the development of cosmeceutical products due to its abilities in skin repair and tissue regeneration. Marine fish-derived peptides have also been utilized for various cosmeceutical applications due to their antioxidant, antimicrobial, and matrix metalloproteinase inhibitory activities. In addition, marine fish-derived proteins and hydrolysates demonstrated efficient anti-photoaging activity. The present review highlights and presents an overview of the current status of the isolation and applications of marine fish-derived proteins and peptides. This review also demonstrates that marine fish-derived proteins and peptides have high potential for biocompatible and effective cosmeceuticals.

Enzymatic Processes in Marine Biotechnology

In previous review articles the attention of the biocatalytically oriented scientific community towards the marine environment as a source of biocatalysts focused on the habitat-related properties of marine enzymes. Updates have already appeared in the literature, including marine examples of oxidoreductases, hydrolases, transferases, isomerases, ligases, and lyases ready for food and pharmaceutical applications. Here a new approach for searching the literature and presenting a more refined analysis is adopted with respect to previous surveys, centering the attention on the enzymatic process rather than on a single novel activity. Fields of applications are easily individuated: (i) the biorefinery value-chain, where the provision of biomass is one of the most important aspects, with aquaculture as the prominent sector; (ii) the food industry, where the interest in the marine domain is similarly developed to deal with the enzymatic procedures adopted in food manipulation; (iii) the selective and easy extraction/modification of structurally complex marine molecules, where enzymatic treatments are a recognized tool to improve efficiency and selectivity; and (iv) marine biomarkers and derived applications (bioremediation) in pollution monitoring are also included in that these studies could be of high significance for the appreciation of marine bioprocesses.

Biochemical characterization, cloning and molecular modeling of a digestive lipase from red seabream (Pagrus major): Structural explanation of the interaction deficiency with colipase and lipidic interface

Red seabream digestive lipase (RsDL) was purified from fresh pyloric caeca. Pure RsDL has an apparent molecular mass of 50 kDa. The RsDL is more active on short-chain triacylglycerols (TC₄), and enzymatic activity decreases when medium (TC₈) or long-chain (olive oil) triacylglycerols were used as substrates. The specific activities of RsDL are very weak as compared to those obtained with classical pancreatic lipases. No colipase was detected in the red seabream pyloric caeca. Furthermore, the RsDL was not activated by a mammal colipase. Similar results were reported for annular seabream lipase. In order to explain structurally the discrepancies between sparidae and mammal lipases, genes encoding mature RsDL and five other lipases from sparidae fish species were cloned and sequenced. Phylogenetic studies indicated the closest homology of sparidae lipases to bird pancreatic ones. Structural models were built for annular seabream and RsDL under their closed and open forms using mammal pancreatic lipases as templates. Several differences were noticed when analyzing the amino acids corresponding to those involved in HPL binding to colipase. This is likely to prevent interaction between the fish lipase and the mammalian colipase and may explain the fact that mammalian colipase is not effective in activating sparidae lipases. In addition, several hydrophobic residues, playing a key role in anchoring pancreatic lipase onto the lipid interface, are replaced by polar residues in fish lipases. This might explain the reason why the latter enzymes display weak activity levels when compared to mammalian pancreatic lipases.

Purification and characterization of trypsin from Luphiosilurus alexandri pyloric cecum

Trypsin from L. alexandri was purified using only two purification processes: ammonium sulfate precipitation and anion exchange liquid chromatography in DEAE-Sepharose. Trypsin mass was estimated as 24 kDa through SDS-PAGE, which showed only one band in silver staining. The purified enzyme showed an optimum temperature and pH of 50 °C and 9.0, respectively. Stability was well maintained, with high levels of activity at a pH of up to 11.0, including high stability at a temperature of up to 50 °C after 60 min of incubation. The inhibition test demonstrated strong inhibition by PMSF, a serine protease inhibitor, and Kinetic constants km and kcat for BAPNA were 0.517 mM and 5.0 S-1, respectively. The purified enzyme was also as active as casein, as analyzed by zymography. Therefore, we consider trypsin a promising enzyme for industrial processes, owing to its stability in a wide range of pH and temperature and activity even under immobilization.

Chymotrypsin isolation from jumbo squid (Dosidicus gigas) hepatopancreas: Partial characterization and effect on muscle collagen

Chymotrypsin was purified from jumbo squid hepatopancreas (HP) with 2.4-fold and yield 1.9%, and characterized with a molecular weight of 31 kDa, as estimated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE). Chymotrypsin effect over collagen extracted from the mantle, fins and arms of the jumbo squid was evaluated. The enzyme exhibited the maximum activity at pH 7 and 65°C using Suc-Ala-Ala-Pro-Phe-p-nitroanilide (SAAPNA) as a substrate and it was identified using the specific inhibitors N-tosyl-L-phenylalaninechloromethyl ketone (TPCK) and phenyl methyl sulfonyl fluoride (PMSF), showing residual activities of 6% and 0%, respectively. Furthermore, high activity was observed in the pH range of 4.0 to 8.0. Purified enzyme showed a moderate in vitro activity using muscle collagen as a substrate. Although further research is needed, the results suggest that the enzyme has a potential application where acidic or slightly alkaline conditions are needed.

Enzymes in Fish and Seafood Processing

Enzymes have been used for the production and processing of fish and seafood for several centuries in an empirical manner. In recent decades, a growing trend toward a rational and controlled application of enzymes for such goals has emerged. Underlying such pattern are, among others, the increasingly wider array of enzyme activities and enzyme sources, improved enzyme formulations, and enhanced requirements for cost-effective and environmentally friendly processes. The better use of enzyme action in fish- and seafood-related application has had a significant impact on fish-related industry. Thus, new products have surfaced, product quality has improved, more sustainable processes have been developed, and innovative and reliable analytical techniques have been implemented. Recent development in these fields are presented and discussed, and prospective developments are suggested.

Enzymes from Seafood Processing Waste and Their Applications in Seafood Processing

Commercial fishery processing results in discards up to 50% of the raw material, consisting of scales, shells, frames, backbones, viscera, head, liver, skin, belly flaps, dark muscle, roe, etc. Besides, fishing operations targeted at popular fish and shellfish species also result in landing of sizeable quantity of by-catch, which are not of commercial value because of their poor consumer appeal. Sensitivity to rapid putrefaction of fishery waste has serious adverse impact on the environment, which needs remedial measures. Secondary processing of the wastes has potential to generate a number of valuable by-products such as proteins, enzymes, carotenoids, fat, and minerals, besides addressing environmental hazards. Fishery wastes constitute good sources of enzymes such as proteases, lipases, chitinase, alkaline phosphatase, transglutaminase, hyaluronidase, acetyl glycosaminidase, among others. These enzymes can have diverse applications in the seafood industry, which encompass isolation and modification of proteins and marine oils, production of bioactive peptides, acceleration of traditional fermentation, peeling and deveining of shellfish, scaling of finfish, removal of membranes from fish roe, extraction of flavors, shelf life extension, texture modification, removal of off-odors, and for quality control either directly or as components of biosensors. Enzymes from fish and shellfish from cold habitats are particularly useful since they can function comparatively at lower temperatures thereby saving energy and protecting the food products. Potentials of these applications are briefly discussed.

Preparation, characterisation and use for antioxidant oligosaccharides of a cellulase from abalone (Haliotis discus hannai) viscera

BACKGROUND

In China, abalone (Haliotis discus hannai) production is growing annually. During industrial processing, the viscera, which are abundant of cellulase, are usually discarded or processed into low-value feedstuff. Thus, it is of interest to obtain cellulase from abalone viscera and investigate its application for preparation of functional oligosaccharides.

RESULTS

A cellulase was purified from the hepatopancreas of abalone by ammonium sulfate precipitation and two-steps column chromatography. The molecular weight of the cellulase was 45 kDa on SDS-PAGE. Peptide mass fingerprinting analysis yielded 103 amino acid residues, which were identical to cellulases from other species of abalone. Substrate specificity analysis indicated that the cellulase is an endo-1,4-β-glucanase. Hydrolysis of seaweed Porphyra haitanensis polysaccharides by the enzyme produced oligosaccharides with degree of polymerisation of two to four, whose monosaccharide composition was 58% galactose, 4% glucose and 38% xylose. The oligosaccharides revealed 2,2'-diphenyl-1-picrylhydrazyl free radical as well as hydrogen peroxide scavenging activity.

CONCLUSION

It is feasible and meaningful to utilise cellulase from the viscera of abalone for preparation of functional oligosaccharides. © 2015 Society of Chemical Industry.

Generation and identification of anti-inflammatory peptides from bovine β-casein using enzyme preparations from cod and hog

BACKGROUND

The aim of the present study was to generate and identify potential anti-inflammatory peptides from bovine β-casein with enzyme preparations from cod and hog. Furthermore, the potential of cod trypsin, derived from fishery by-products, to produce these bioactive peptides for replacement of non-food-grade tosyl phenylalanyl chloromethyl ketone (TPCK)-treated porcine trypsin enzyme preparation was evaluated.

RESULTS

Potential anti-inflammatory peptides were obtained by hydrolysis of β-casein with the tryptic enzyme preparations cod trypsin, porcine trypsin (TPCK-treated) and a porcine trypsin and chymotrypsin preparation (PTN 6.0 S). Proteolysates generated with enzyme preparations containing mainly chymotryptic activity (Cryotin, Cryotin F) did not exhibit any effect.

CONCLUSION

The more chymotryptic enzyme activity is present, the lower is the potential anti-inflammatory activity of the hydrolysates in HEK(nfκb-RE) cells. Comparable peptides were produced by application of porcine trypsin (TPCK) and cod trypsin. Therefore, the enzyme preparation cod trypsin can replace the non-food-grade porcine enzyme preparation trypsin (TPCK) for the generation of potential anti-inflammatory peptides from β-casein.

Microbial collagenases: challenges and prospects in production and potential applications in food and nutrition

Microbial collagenases are promising enzymes in view of their extensive industrial and biological applications.

Valorisation of fish by-products against waste management treatments--Comparison of environmental impacts

Reuse and valorisation of fish by-products is a key process for marine resources conservation. Usually, fishmeal and oil processing factories collect the by-products generated by fishing port and industry processing activities, producing an economical benefit to both parts. In the same way, different added-value products can be recovered by the valorisation industries whereas fishing companies save the costs associated with the management of those wastes. However, it is important to estimate the advantages of valorisation processes not only in terms of economic income, but also considering the environmental impacts. This would help to know if the valorisation of a residue provokes higher impact than other waste management options, which means that its advantages are probably not enough for guarantying a sustainable waste reuse. To that purpose, there are several methodologies to evaluate the environmental impacts of processes, including those of waste management, providing different indicators which give information on relevant environmental aspects. In the current study, a comparative environmental assessment between a valorisation process (fishmeal and oil production) and different waste management scenarios (composting, incineration and landfilling) was developed. This comparison is a necessary step for the development and industrial implementation of these processes as the best alternative treatment for fish by-products. The obtained results showed that both valorisation process and waste management treatments presented similar impacts. However, a significant benefit can be achieved through valorisation of fish by-products. Additionally, the implications of the possible presence of pollutants were discussed.

Marine-Based Nutraceuticals: An Innovative Trend in the Food and Supplement Industries

Recent trends in functional foods and supplements have demonstrated that bioactive molecules play a major therapeutic role in human disease. Nutritionists and biomedical and food scientists are working together to discover new bioactive molecules that have increased potency and therapeutic benefits. Marine life constitutes almost 80% of the world biota with thousands of bioactive compounds and secondary metabolites derived from marine invertebrates such as tunicates, sponges, molluscs, bryozoans, sea slugs and many other marine organisms. These bioactive molecules and secondary metabolites possess antibiotic, antiparasitic, antiviral, anti-inflammatory, antifibrotic and anticancer activities. They are also inhibitors or activators of critical enzymes and transcription factors, competitors of transporters and sequestrants that modulate various physiological pathways. The current review summaries the widely available marine-based nutraceuticals and recent research carried out for the purposes of isolation, identification and characterization of marine-derived bioactive compounds with various therapeutic potentials.

Digestive alkaline proteases from thornback ray (Raja clavata): Characteristics and applications

This study describes the characterization of a crude protease extract from thornback ray (Raja clavata) and its evaluation in liquid detergent and in deproteinizattion of shrimp waste. At least five clear caseinolytic proteases bands were observed in a zymogram. The crude protease showed optimum activity at pH 8.0 and 50 °C, and it was highly stable over pH range from 8.0 to 11.0. Proteolytic enzymes were very stable in non-ionic surfactants and in the presence of oxidizing agents, maintaining 70% of their activity after incubation for 1 h at 30 °C in the presence of 1% sodium perborate. In addition, they showed high stability and compatibility with various liquid laundry-detergents available in the Tunisian market. The crude extract retained 100% of its activity after preincubation for 60 min at 30 °C in the presence of Nadhif Perfect, Textil and Carrefour laundry detergents. Further, proteases from R. clavata viscera were used for shrimp waste deproteinization in the process of chitin preparation. The percent of protein removal after 3 h hydrolysis at 45 °C with an enzyme/substrate ratio of 30 U/mg of proteins was 74%. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process.

Characterization of digestive enzymes from de-oiled mackerel (Scomber japonicus) muscle obtained by supercritical carbon dioxide and n-hexane extraction as a comparative study

The oil in mackerel muscle was extracted using an environmental friendly solvent, supercritical carbon dioxide (SC-CO2) at a semi-batch flow extraction process and an n-hexane. The SC-CO2 was carried out at temperature 45 °C and pressures ranging from 15 to 25 MPa. The flow rate of CO2 (27 g/min) was constant at the entire extraction period of 2 h. The highest oil extracted residues after SC-CO2 extraction was used for activity measurement of digestive enzymes. Four digestive enzymes were found in water soluble extracts after n-hexane and SC-CO2 treated samples. Amylase, lipase and trypsin activities were higher in water soluble extracts after SC-CO2 treated samples except protease. Among the four digestive enzymes, the activity of amylase was highest and the value was 44.57 uM/min/mg of protein. The water soluble extracts of SC-CO2 and n-hexane treated mackerel samples showed same alkaline optimum pH and pH stability for each of the digestive enzymes. Optimum temperature of amylase, lipase, protease and trypsin was 40, 50, 60 and 30 °C, respectively of both extracts. More than 80 % temperature stability of amylase, lipase, protease and trypsin were retained at mentioned optimum temperature in water soluble extracts of both treated samples. Based on protein patterns, prominent protein band showed in water soluble extracts after SC-CO2 treated samples indicates no denaturation of protein than untreated and n-hexane.

Trypsin from the digestive system of carp Cirrhinus mrigala: purification, characterization and its potential application

Trypsin was purified 35.64-fold with 4.97% recovery from the viscera of carp Cirrhinus mrigala (mrigal) by ammonium sulfate precipitation, ion exchange and affinity chromatography. The purified enzyme was active at a wide range of pH (7.0-9.2) and temperature (10-50°C). The purified enzyme exhibited high thermal stability up to 50°C for 1h. The enzyme activity was stabilized by Ca(+2) (2mM) up to 7h at 40°C. The Km and kcat values of purified enzyme were 0.0672 mM and 92.09/s/mM, respectively. Soybean trypsin inhibitor and phenylmethylsulphonylflouride completely inhibited the enzyme activity. The specific inhibitor of trypsin, N-α-p-tosyl-L-lysine chloromethyl ketone inhibited 99.67% activity. Na(+), K(+) and Li(+) inhibited 20.99 ± 5.25%, 16.53 ± 4.80% and 18.99 ± 1.42% of enzyme activity, respectively. Divalent ions Mg(+2), Zn(+2), Co(+2), Hg(+2) and Cd(+2) inhibited 21.61 ± 2.22%, 31.62 ± 1.78%, 31.62 ± 1.96%, 85.68 ± 1.51% and 47.95 ± 2.13% enzyme activity, respectively. SDS-PAGE showed that the molecular mass of purified enzyme was 21.7 kDa. MALDI-TOF study showed a peptide sequence of AFCGGSLVNENKMHSAGHCYKSRIQV at the N-Terminal. This sequence recorded 76-84% identity with trypsin from Thunnus thynnus and other fish species. This confirmed that the purified protein was trypsin. The purified enzyme has potential applications in detergent and food industry because of its thermal stability and alkaline nature.

Angiotensin-I converting enzyme inhibitory peptides from antihypertensive skate (Okamejei kenojei) skin gelatin hydrolysate in spontaneously hypertensive rats

The aim of this study was to investigate antihypertensive effect of bioactive peptides from skate (Okamejei kenojei) skin gelatin. The Alcalase/protease gelatin hydrolysate below 1 kDa (SAP) exhibited the highest angiotensin-I converting enzyme (ACE) inhibition compared to other hydrolysates. SAP can decrease systolic blood pressure significantly in spontaneously hypertensive rats. SAP inhibited vasoconstriction via PPAR-γ expression, activation and phosphorylation of eNOS in lungs. Moreover, the expression levels of endothelin-1, RhoA, α-smooth muscle actin, cleaved caspase 3 and MAPK were decreased by SAP in lungs. Vascularity, muscularization and cellular proliferation in lungs were detected by immunohistochemical staining. Finally, two purified peptides (LGPLGHQ, 720Da and MVGSAPGVL, 829Da) showed potent ACE inhibition with IC50 values of 4.22 and 3.09 μM, respectively. These results indicate that bioactive peptides isolated from skate skin gelatin may serve as candidates against hypertension and could be used as functional food ingredients.

Trypsin isozymes in the lobster Panulirus argus (Latreille, 1804): from molecules to physiology

Trypsin enzymes have been studied in a wide variety of animal taxa due to their central role in protein digestion as well as in other important physiological and biotechnological processes. Crustacean trypsins exhibit a high number of isoforms. However, while differences in properties of isoenzymes are known to play important roles in regulating different physiological processes, there is little information on this aspect for decapod trypsins. The aim of this review is to integrate recent findings at the molecular level on trypsin enzymes of the spiny lobster Panulirus argus, into higher levels of organization (biochemical, organism) and to interpret those findings in relation to the feeding ecology of these crustaceans. Trypsin in lobster is a polymorphic enzyme, showing isoforms that differ in their biochemical features and catalytic efficiencies. Molecular studies suggest that polymorphism in lobster trypsins may be non-neutral. Trypsin isoenzymes are differentially regulated by dietary proteins, and it seems that some isoenzymes have undergone adaptive evolution coupled with a divergence in expression rate to increase fitness. This review highlights important but poorly studied issues in crustaceans in general, such as the relation among trypsin polymorphism, phenotypic (digestive) flexibility, digestion efficiency, and feeding ecology.

Anti-bactericidal properties of stingray Dasyatis pastinaca groups V, IIA, and IB phospholipases A2: a comparative study

Group IIA secreted phospholipase A2 (group IIA sPLA2) is known to display potent Gram-positive bactericidal activity in vitro and in vivo. We have analyzed the bactericidal activity of the full set of native stingray and dromedary groups V, IIA, and IB sPLA2s on several Gram-positive and Gram-negative strains. The rank order potency among both marine and mammal sPLA2s against Gram-positive bacteria is group IIA > V > IB, whereas Gram-negative bacteria exhibited a much higher resistance. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2.The bactericidal efficiency of groups V and IIA sPLA2s was shown to be dependent upon the presence of calcium ions and to a less extent Mg(2+) ions and then a correlation could be made to its hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray and dromedary groups V, IIA, and IB sPLA2s present no cytotoxicity after their incubation with MDA-MB-231cells. stingray groups V and IIA sPLA2s, like mammal ones, may be considered as future therapeutic agents against bacterial infections.

RNA-Seq reveals the dynamic and diverse features of digestive enzymes during early development of Pacific white shrimp Litopenaeus vannamei

The Pacific white shrimp (Litopenaeus vannamei), with high commercial value, has a typical metamorphosis pattern by going through embryo, nauplius, zoea, mysis and postlarvae during early development. Its diets change continually in this period, and a high mortality of larvae also occurs in this period. Since there is a close relationship between diets and digestive enzymes, a comprehensive investigation about the types and expression patterns of all digestive enzyme genes during early development of L. vannamei is of considerable significance for shrimp diets and larvae culture. Using RNA-Seq data, the types and expression characteristics of the digestive enzyme genes were analyzed during five different development stages (embryo, nauplius, zoea, mysis and postlarvae) in L. vannamei. Among the obtained 66,815 unigenes, 296 were annotated as 16 different digestive enzymes including five types of carbohydrase, seven types of peptidase and four types of lipase. Such a diverse suite of enzymes illustrated the capacity of L. vannamei to exploit varied diets to fit their nutritional requirements. The analysis of their dynamic expression patterns during development also indicated the importance of transcriptional regulation to adapt to the diet transition. Our study revealed the diverse and dynamic features of digestive enzymes during early development of L. vannamei. These results would provide support to better understand the physiological changes during diet transition.

Effect of ultrasound on the activity and conformation of α-amylase, papain and pepsin

The effect of ultrasound on the activity of α-amylase, papain and pepsin was investigated and the mechanism of the effect was explored by determining their conformational changes. With the irradiation of power ultrasound, the activity of α-amylase and papain was inhibited, while the activity of pepsin was activated. According to the analysis of circular dichroism, Fourier transform infrared and fluorescence spectroscopy, the πo → π(∗) amide transitions and secondary structural components, especially β-sheet, of these three enzymes were significantly influenced by ultrasound. The tryptophan fluorescence intensity of the three enzymes was also observed to be affected by sonication. Furthermore, it was found that the pepsin molecule might gradually be resistant to prolonged ultrasonic treatment and recover from the ultrasound-induced damage to its original structure. The results suggested that the activity of α-amylase, papain and pepsin could be modified by ultrasonic treatment mainly due to the variation of their secondary and tertiary structures.

Microbial successions and metabolite changes during fermentation of salted shrimp (saeu-jeot) with different salt concentrations

To investigate the effects of salt concentration on saeu-jeot (salted shrimp) fermentation, four sets of saeu-jeot samples with 20%, 24%, 28%, and 32% salt concentrations were prepared, and the pH, bacterial and archaeal abundances, bacterial communities, and metabolites were monitored during the entire fermentation period. Quantitative PCR showed that Bacteria were much more abundant than Archaea in all saeu-jeot samples, suggesting that bacterial populations play more important roles than archaeal populations even in highly salted samples. Community analysis indicated that Vibrio, Photobacterium, Psychrobacter, Pseudoalteromonas, and Enterovibrio were identified as the initially dominant genera, and the bacterial successions were significantly different depending on the salt concentration. During the early fermentation period, Salinivibrio predominated in the 20% salted samples, whereas Staphylococcus, Halomonas, and Salimicrobium predominated in the 24% salted samples; eventually, Halanaerobium predominated in the 20% and 24% salted samples. The initially dominant genera gradually decreased as the fermentation progressed in the 28% and 32% salted samples, and eventually Salimicrobium became predominant in the 28% salted samples. However, the initially dominant genera still remained until the end of fermentation in the 32% salted samples. Metabolite analysis showed that the amino acid profile and the initial glycerol increase were similar in all saeu-jeot samples regardless of the salt concentration. After 30–80 days of fermentation, the levels of acetate, butyrate, and methylamines in the 20% and 24% salted samples increased with the growth of Halanaerobium, even though the amino acid concentrations steadily increased until approximately 80–107 days of fermentation. This study suggests that a range of 24–28% salt concentration in saeu-jeot fermentation is appropriate for the production of safe and tasty saeu-jeot.

Immobilization of papain on nanoporous silica

Immobilization mode, microscopic structure and adsorption mechanism of papain on nanoporous silica surface.

Enzymatic properties of stingray Dasyatis pastinaca group V, IIA and IB phospholipases A(2): a comparative study

In the present study, we have purified the group V phospholipase from the heart of cartilaginous fish stingray Dasyatis pastinaca and compared its biochemical properties with group IIA (sPLA2-IIA) and IB (sPLA2-IB) phospholipases previously purified from pancreas and intestine, respectively. Group V phospholipase (sPLA2-V) was purified to homogeneity by heat treatment, ammonium sulphate precipitation and RP-HPLC. The N-terminal sequence of the purified sPLA2-V exhibits a high degree of homology with those of mammal. The enzyme was found to be monomeric with a molecular mass estimation of 14 kDa. The specific activity of the purified enzyme, measured at pH 8 and 37 °C was 52 U/mg. Like sPLA2-IB and sPLA2-IIA, the sPLA2-V is found to be stable between pH 3 and 11 after 30 min of incubation. The purified sPLA2-V retained 65% of its activity after 10 min of incubation at 70 °C and it absolutely requires Ca(2+) for enzymatic activity. In addition it displayed high tolerance to organic solvents. Kinetic parameters Kmapp, kcat and the deduced catalytic efficiency (kcat/Kmapp) of the purified group-V, -IB and -IIA PLA2s were determined using phosphatidylethanolamine (PE), phosphatidylcholine (PC) or phosphatidylserine (PS) as substrate. The three enzymes hydrolyze the zwiterionic PE and PC substrates more efficiently than anionic PS substrate.

Purification and characterization of chymotrypsin from viscera of vermiculated sailfin catfish, Pterygoplichthys disjunctivus, Weber, 1991

Pterygoplichthys disjunctivus viscera chymotrypsin was purified by fractionation with ammonium sulfate (30-70 % saturation), gel filtration, affinity, and ion exchange chromatography. Chymotrypsin molecular weight was approximately 29 kDa according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), shown a single band in zymogram. Electrofocusing study suggested being an anionic enzyme (pI ≈ 3.9), exhibiting maximal activity at pH 9 and 50 °C, using Suc-Ala-Ala-Pro-Phe-p-nitroanilide (SAAPNA) as substrate. Enzyme was effectively inhibited by phenyl methyl sulfonyl fluoride (PMSF) (99 %), and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) (94 %). Enzyme activity was affected by the following ions in decreasing order: Hg(2+), Fe(2+), Cu(2+), Li(1+), Mg(2+), K(1+), Mn(2+), while Ca(2+) had no effect. Chymotrypsin activity decreased continuously as NaCl concentration increased (from 0 to 30 %). K m and V max values were 0.72 ± 1.4 mM and 1.15 ± 0.06 μmol/min/mg of protein, respectively (SAAPNA as substrate). Results suggest the enzyme has a potential application where low processing temperatures are needed, such as in fish sauce production.

Potential of chicken by-products as sources of useful biological resources

By-products from different animal sources are currently being utilised for beneficial purposes. Chicken processing plants all over the world generate large amount of solid by-products in form of heads, legs, bones, viscera and feather. These wastes are often processed into livestock feed, fertilizers and pet foods or totally discarded. Inappropriate disposal of these wastes causes environmental pollution, diseases and loss of useful biological resources like protein, enzymes and lipids. Utilisation methods that make use of these biological components for producing value added products rather than the direct use of the actual waste material might be another viable option for dealing with these wastes. This line of thought has consequently led to researches on these wastes as sources of protein hydrolysates, enzymes and polyunsaturated fatty acids. Due to the multi-applications of protein hydrolysates in various branches of science and industry, and the large body of literature reporting the conversion of animal wastes to hydrolysates, a large section of this review was devoted to this subject. Thus, this review reports the known functional and bioactive properties of hydrolysates derived from chicken by-products as well their utilisation as source of peptone in microbiological media. Methods of producing these hydrolysates including their microbiological safety are discussed. Based on the few references available in the literature, the potential of some chicken by-product as sources of proteases and polyunsaturated fatty acids are pointed out along with some other future applications.

Potential use of Atlantic cod trypsin in biomedicine

Surface proteins of viruses and bacteria used for cell attachment and invasion are candidates for degradation by proteases. Trypsin from Atlantic cod (Gadus morhua) was previously demonstrated to have efficacy against influenza viruses in vitro and on skin. In this paper, cod trypsin is shown to be 3–12 times more effective in degrading large native proteins than its mesophilic analogue, bovine trypsin. This is in agreement with previous findings where cod trypsin was found to be the most active among twelve different proteases in cleaving various cytokines and pathological proteins. Furthermore, our results show that cod trypsin has high efficacy against herpes simplex virus type 1 (HSV-1) and the respiratory syncytial virus (RSV) in vitro. The results on the antipathogenic properties of cod trypsin are important because rhinovirus, RSV, and influenza are the most predominant pathogenic viruses in upper respiratory tract infections. Results from a clinical study presented in this paper show that a specific formulation containing cod trypsin was preferred for wound healing over other methods used in the study. Apparently, the high digestive ability of the cold-adapted cod trypsin towards large native proteins plays a role in its efficacy against pathogens and its positive effects on wounds.

Optimization and Immobilization of Purified Labeo rohita Visceral Protease by Entrapment Method

The purified fish visceral protease enzyme was immobilized by using various concentrations of sodium alginate and calcium chloride to optimize the best concentration for the formation of the beads. Then it was characterized by assaying the optimal pH, temperature, storage stability and reusability. The results on immobilization with sodium alginate and calcium chloride showed that a combination of 2% sodium alginate and 0.3 M calcium chloride weas found to be the optimum concentration for the formation of spherical and stable beads, this gave a maximal entrapped activity of 48.31%, and there was no change in the optimum pH 8.0 and temperature 40°C of protease before and after entrapment. The results on stability and reusability indicated that it was stable at 4°C retaining 100% residual activity after 5 days of storage and 67% loss of activity after ten days of storage and it retained 100% residual activity on the first reuse, 75% residual activity on the second reuse, 25% residual activity on the third use and complete loss in the activity on the fourth reuse.