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The β′-component, a major allergen found in fish roe, is synthesized in the liver of female fish as part of the precursor of the egg yolk protein vitellogenin (Vg). Vg is distributed through the bloodstream and contributes to ovary development. In the present study, β′-component, present in Vg fragments, was detected in the muscles and internal organs of mature female salmon, with concentrations exceeding the recommended labeling level under Japan's food allergy labeling system. Additionally, total protein extracted from tissues of female salmon reacted with immunoglobulin E antibody against the salmon roe β′-component. No β′-component was detected in the tissues of mature male fish in the absence of sex hormone stimulation from females nor in immature salmon without sexual differentiation, but excess stimulation of the female sex hormone induced Vg synthesis containing the β′-component in the male fish. These findings suggest that taking into account fish sex, maturity, and sexual isolation of mature male fish could improve the safety of salmon meat for individuals with salmon roe allergy. [ABSTRACT FROM AUTHOR]

Summary: Our previous study found that glycation with uronic acid‐type reducing sugar enhanced the anti‐inflammatory effect of fish myofibrillar protein (Mf) via the Maillard reaction, and the molecular mechanism of enhanced anti‐inflammatory effect was investigated in this study. Mf was glycated with various reducing sugars at 60 °C and 35% relative humidity. After pepsin‐trypsin digestion, the anti‐inflammatory effects were evaluated by assessing secretions of pro‐inflammatory cytokines and expressions of LPS‐stimulated signalling pathway‐related genes in RAW 264.7 macrophages. Mf glycated with uronic acid‐type reducing sugars: glucuronic acid, galacturonic acid and alginate oligosaccharide, suppressed expression of cd14 and further suppressed expressions of tlr4 and myd88 comparing with intact and glycated Mf with glucose and galactose. Furthermore, uronic acid‐glycated Mf significantly suppressed expressions and secretions of pro‐inflammatory cytokines. The results indicate that uronic acid‐type glycation enhances anti‐inflammatory effect of Mf by attenuating expression of cd14 and enhancing the Mf‐induced suppression in TLR4‐MyD88‐dependent inflammatory signalling pathway. [ABSTRACT FROM AUTHOR]

Purpose: Sturgeon notochord, a by-product in the sturgeon aquaculture industry, is a promising yet underutilized source of type II collagen. In this study, functionally enhanced collagen peptides (CPs) were developed from notochordal collagen using optimal glycation via the Maillard reaction, and the potential applications of the by-product and possible contributions to the valorization of the sturgeon aquaculture industry were determined. Methods: CP prepared by papain digestion was mixed with alginate oligosaccharide (AO), glucose (Glu), or glucuronic acid (GluA), lyophilized, and then glycation at 80 °C and 75% relative humidity for up to 8 h. Amino acid analysis was performed to evaluate the formation of glycated CP (CP–sugars). The health-beneficial functions, antioxidative and anti-inflammatory activities of CP–sugars were evaluated by the ABTS radical scavenging assay and by quantification of inflammatory compound (tumor necrosis factor-α and nitric oxide) production in LPS-stimulated macrophages, respectively. Results: During the glycation process, reducing sugars were reacted with lysine and arginine in CP. GluA had a higher reactivity to the reactive amino acids than that of Glu and AO. The antioxidant and anti-inflammatory functions of CP–sugars were increased with the glycation processes, and AO-glycation enhanced the health-beneficial functions of CP without a marked loss of reactive amino acids compared with the Glu- and GluA-glycations. Conclusion: The appropriate glycation via the Maillard reaction is an effective way to simultaneously enhance the antioxidant and anti-inflammatory functions of CP from sturgeon notochord to facilitate its application as a functional food material. [ABSTRACT FROM AUTHOR]

A separation process was established to sequentially fractionate and recover three anti-inflammatory components derived from sugars, phycobiliprotein, and chlorophyll from the hot-air-dried thalli of the red alga dulse (Palmaria palmata). The developed process consisted of three steps, without the use of organic solvents. In Step I, the sugars were separated by disrupting the cell wall of the dried thalli with a polysaccharide-degrading enzyme, and a sugar-rich extract (E1) was obtained by precipitating the other components, which were simultaneously eluted by acid precipitation. In Step II, the residue suspension from Step I was digested with thermolysin to obtain phycobiliprotein-derived peptides (PPs), and a PP-rich extract (E2) was obtained by separating the other extracts using acid precipitation. In Step III, solubilized chlorophyll was obtained by heating the residue, which was acid-precipitated, neutralized, and re-dissolved to concentrate the chlorophyll-related components (Chls)-rich extract (E3). These three extracts suppressed inflammatory-cytokine secretion by lipopolysaccharide (LPS)-stimulated macrophages, confirming that the sequential procedure had no negative effects on the activities of any of the extracts. The E1, E2, and E3 were rich in sugars, PPs, and Chls, respectively, indicating that the anti-inflammatory components were effectively fractionated and recovered through the separation protocol. [ABSTRACT FROM AUTHOR]

To evaluate the safety of Terasi (Indonesian fermented shrimp paste), the product characteristics and allergenicity of 20 types of Indonesian commercial Terasi (ICT) that meet the Indonesian National Standard were evaluated, with a focus on the major shrimp allergen tropomyosin (TM). Marked protein hydrolysis of shrimp muscle occurred in all ICT samples, and no protein fragments or specific reaction of anti-TM immunoglobulin (Ig)G were observed in SDS-PAGE or immunoblot assays. In a competitive enzyme-linked immunosorbent assay using shrimp allergenic patient sera, we observed a markedly diminished specific IgE reaction of ICT compared with that of shrimp muscle, whereas the IgE-binding ability remained in all ICT samples. No clear correlation was found between the degree of protein hydrolysis and IgE reactivity. These results indicate that ICT could be defined as a low–allergenic processed seafood, but has the possibility to be a causative food for shrimp allergy. Direct immunological evaluation is required establishing the food safety of ICT, because assessments of protein profiles and hydrolysis are not useful for determining the safety of Terasi. [ABSTRACT FROM AUTHOR]

In manufacturing industries that use seaweeds containing high moisture as raw materials, the volume reduction of seaweeds is a basic requirement for their efficient storage, transport, and processing. In this study, fresh red algae, dulse Palmaria palmata was hot air–dried at 30 and 60 °C with or without pre-freezing for 1 week, and anti-inflammatory components, phycobiliprotein (P) and chlorophyll a-related compounds (C) were extracted together using water from the dried thalli. The water extractability of each was diminished by pre-freezing and markedly impaired by hot-air drying of the raw dulse. In contrast, the anti-inflammatory activity of thermolysin digested P and C mixtures, which was evaluated using lipopolysaccharide-stimulated murine macrophages, persisted despite exposure of the raw materials to the freezing and hot-air-drying processes. In addition, the deterioration in the extractability of P caused by hot-air drying was recovered by the enzymatic degradation of the cell wall hardened by drying, and the water extract showed strong anti-inflammatory activity. These results indicated that hot-air–dried dulse can be used as an anti-inflammatory material by utilizing the appropriate physicochemical procedure for restoring the extractability of the anti-inflammatory components, and enzymatic algal cell degradation is one such practical countermeasure. [ABSTRACT FROM AUTHOR]

To improve the antioxidant activity of collagen molecules using Maillard-type glycation, the relation between antioxidant activity and progress indexes for the Maillard reaction must be understood. In this study, lyophilized tilapia scale collagen was mixed with a half weight of alginate oligosaccharide (AO) or glucose and incubated at 60 °C and 35% relative humidity for up to 18 h to produce the Maillard-type glycated collagen (C-AO and C-Glu, respectively). As glycation progressed, the amount of conjugated sugar coupled with UV-vis absorbance at 294 nm and 420 nm increased more rapidly in C-Glu than in C-AO, and the available lysine decreased rapidly in C-Glu compared with C-AO. The early-to-middle- and late-stage products of the Maillard reaction were involved in enhanced antioxidant activity of digested C-AO and digested C-Glu, respectively. Additionally, C-AO acquired the antioxidant activity without marked available lysine loss. The cytoprotective effect of collagen in H2O2-induced damage was enhanced by glycation, achieved by reducing malondialdehyde content and increasing superoxide dismutase and catalase activities. These results indicate that AO is an excellent reducing sugar that enhances the health benefits of collagen without excessive loss of lysine, which is a nutritional problem of the Maillard-type glycation. [ABSTRACT FROM AUTHOR]

Male 5-week-old F344 rats were fed four types of experimental diet with different Ca and protein sources for 30 days, and the effect of feeding retort-treated herring bone on Ca absorption and bone metabolism were examined. The experimental diets were as follows: AIN-93G (casein-based standard breeding diet) containing 0.5% Ca from CaCO3 (C); modified AIN-93G containing 0.25% Ca from CaCO3 (L); retorted herring meat with bone containing 0.25% Ca from edible bones (PHB); and retorted deboned herring meat containing 0.06% and 0.19% Ca from retorted bones and CaCO3 (PH). There was no difference in weight increase among the groups during the feeding period. The Ca absorption rate (CAR) in the PHB and PH groups after 4 weeks was slightly lower than that of L, whereas CAR did not differ between PHB and PH. Furthermore, the involvement of absorbed calcium in bone metabolism, as assessed using the bone turnover markers, did not differ between the PHB, PH, and L groups. In conclusion, fish bones rendered edible after retort treatment are a good source of Ca, the nutritional value of which is similar to that of CaCO3, indicating that retort treatment is a suitable cooking method for using fish as a Ca source. [ABSTRACT FROM AUTHOR]

Chum salmon myofibrillar protein (Mf) digested by pepsin-trypsin (dMf) was conjugated to alginate oligosaccharide (AO) through the Maillard reaction between the lysine residues in the dMf and the reducing end-groups of AO. The dMf-AO conjugate strongly suppressed the production of inflammatory cytokines, particularly tumor necrosis factor-α and interleukin-6, in lipopolysaccharide-stimulated murine macrophages. The anti-inflammatory effect was enhanced with increasing amounts of AO bound to dMf through the Maillard reaction, and the subsequent process of the Maillard reaction was involved in the enhancement of the anti-inflammatory activity. AO-conjugated peptides, the major anti-inflammatory components contained in the dMf-AO conjugate, were successfully recovered using isoelectric focusing without the use of carrier ampholytes (autofocusing); they were effectively concentrated in acidic peptide fractions, with the negative charge of the carboxyl groups of AO contributing to this separation. In conclusion, the combined use of AO conjugation and autofocusing is a useful method for producing novel anti-inflammatory peptides from fish Mf. [ABSTRACT FROM AUTHOR]

The major allergenic protein in grey mullet roe was immunologically characterized using rabbit IgG against the β′-component, which is a vitellogenin fragment and the major allergen in chum salmon roe, and the IgE cross-reactivity between salmon and mullet roe was examined using chum salmon roe-allergic patients' sera. Grey mullet β′-component was identified in the yolk protein and consisted of 16 and 30 kDa proteins that showed marked reaction with the anti-β′-component IgG and shared N-terminal amino acid sequence similarity with vitellogenin. The grey mullet β′-component consisted of six different isoforms generated from vitellogenin A and vitellogenin B, and they inhibited the IgE-binding reaction between chum salmon β′-component and a chum salmon roe-allergic patient's serum. Thus, grey mullet roe may be an allergenic seafood capable of introducing IgE cross-reactivity to chum salmon roe through the β′-component. [ABSTRACT FROM AUTHOR]

The efficacy of the controlled Maillard reaction with alginate oligosaccharide (AO) in a dry state was examined for development of an anti-inflammatory compound from fish myofibrillar protein (Mf). Lyophilized Mf from spawned-out chum salmon was mixed with AO (half of the total protein weight) and incubated at 60 °C and 35 % relative humidity for 0-6 h, followed by digestion with pepsin and trypsin. The anti-inflammatory activity of the digested peptide was improved with the progress of the AO conjugation, and dMSA4 (prepared from Mf-AO conjugate by reaction for 4 h, with 49.6 μg/mg protein of AO attached) was most effective in inhibiting secretions of inflammation-related compounds in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Likewise, dMSA4 suppressed the LPS-induced gene and protein expression of inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-6, and cyclooxygenase (COX)-2, while COX-1 expression was unaffected. Furthermore, oral administration of dMSA4 and the Mf-AO conjugate prior to proteolysis inhibited carrageenan-induced paw volume expansion in mice. These results indicate that AO conjugation using the controlled Maillard reaction in a dry state is a useful approach for enhancing the anti-inflammatory activity of salmon Mf as a nutraceutical food material. [ABSTRACT FROM AUTHOR]

Molecular characterization of a major allergen from salmon roeSalmon roe has a high allergic potency and often causes anaphylaxis in Japan. The major allergic protein of salmon roe is β′-component, which is a 35kDa vitellogenin fragment consisting of two subunits. To elucidate structural information and immunological characteristics, β′-component and the subunit components were purified from chum salmon (Onchorhincus keta) roe and vitellogenin-encoding mRNA was used to prepare β′-component subunit-encoding cDNA. This was PCR-amplified, cloned and sequenced and the deduced amino acid sequence compared with partial sequences of β′-component obtained by peptide mapping. The recombinant β′-component subunit was produced by bacterial expression in Escherichia coli and its IgE-binding ability was measured by ELISA using the sera of a patient allergic to salmon roe. This was then compared with that of the native β′-component with and without carboxymethylation. Following successful cloning of the cDNA encoding the β′-component subunit, 170 amino acid residues were deduced and matched with the amino acid sequences of 121 and 88 residues in the 16kDa and 18kDa subunits, respectively. The sequences of both β′-component subunits were almost identical, and the predicted secondary structure of the β′-component showed a high content of β-pleated sheets and no α-helices. There was no difference in IgE-binding ability between the native and recombinant β′-component subunits at the same protein concentration, regardless of carboxymethylation. In conclusion, β′-component is a homodimer protein composed of two isoform subunits having the same level of IgE-binding ability and, therefore, allergenic identity. [ABSTRACT FROM PUBLISHER]

Marine brown algae are rich in sulfated polysaccharides, which have the ability to form gels and viscous solution. Sulfated polysaccharides exhibit many biological activities; however, little is known whether the viscoelastic property in the polysaccharide extract is correlated with biological activities. We examined the immunomodulatory properties of highly viscous polysaccharide extract (HVPE) from Gagome Kjellmaniella crassifolia in a murine model, and the effects were compared with those of a less viscous polysaccharide extract (LVPE). HVPE or LVPE (10, 30, and 100 mg/kg/day) were orally administered to C57BL/6 mice for 14 days. Secretions of cytokine and IgA in Con A-stimulated spleen and Peyer's patch (PP) cells and phagocytic activity of peritoneal macrophages was determined. IFN-γ, IL-12, IL-6, and IgA secretions showed high levels in spleen cell cultures from mice administered HVPE, whereas these effects were diminished in the LVPE-administered mice. The phagocytic activity of peritoneal macrophages was enhanced by the continuous oral administration of HVPE, and these effects were higher than those of LVPE. Furthermore, an increase in IgA secretion by administration of HVPE was observed in Con A-stimulated PP cells. These results suggest that the polysaccharide extract from K. crassifolia has immunomodulatory activities, which depend on the viscosity. [ABSTRACT FROM AUTHOR]

ABSTRACT The potential use of trypsin inhibitors (TI) present in the viscera of Japanese common squid ( Todarodes pacificus) was examined for diabetes treatment. In a single-glucose tolerance test, the crude TI (C-TI) fraction significantly stimulated insulin secretion by normal Wistar rats and by diabetic GK rats. The highly purified TI (H-TI) fraction displayed the same effect on the glucose tolerance test with the GK rats. The TI activity of C-TI was not decreased by pepsin or chymotrypsin digestion in vitro, and the C-TI fraction did not have α-glucosidase inhibitory activity. These results indicate that the substance with the stimulating effect on insulin secretion in rats is the squid TI and that the hypoglycemic effect on glucose tolerance in GK rats is related to an improvement of insulin secretion due to the squid TI. PRACTICAL APPLICATIONS In previous study, the biochemical properties and hypoglycemic effects of squid trypsin inhibitor on diabetic GK rats were analyzed. Here, we showed its resistance to digestive enzyme such as chymotrypsin and pepsin. Further squid trypsin inhibitor stimulates the insulin secretion in GK rats. These results clearly suggests that squid TI retains its activity in duodenum and stimulates the secretion of cholecystokinin which induce the insulin secretion in pancreas. Therefore, squid visera trypsin inhibitor is a potent reagent for lowering blood glucose level. [ABSTRACT FROM AUTHOR]

Complementary DNA clones encoding trypsins were isolated from pyloric ceca of cold-adapted fish, walleye pollock ( Theragra chalcogramma) (WP-T) and Arctic cod ( Boreogadus saida) (AC-T). The isolated full-length cDNA clones of WP-T and AC-T were 852 and 860 bp, respectively, and both cDNAs were contained an open reading frame of 726 bp. WP-T and AC-T seemed to be synthesized as preproenzyme that contains a signal peptide, an activation peptide, and a mature trypsin. Although the amino acid sequence identities of WP-T and AC-T to that of bovine trypsin were 64 and 63%, respectively, they completely conserved the structural features for catalytic function of trypsin. On the other hand, WP-T and AC-T possessed the four Met residues (Met135, Met145, Met175 and Met242) in their molecules and the deletion of Tyr151 and substitution of Pro152 for Gly in their autolysis loops when aligned with the sequences of tropical-zone fish and bovine trypsins. In addition, the contents of charged amino acid residues at the N-terminal regions (positions 20-50) of WP-T and AC-T were extremely higher than those of other fish and bovine trypsins. Moreover, one amino acid (Asn72) and two amino acids (Asn72 and Val75) coordinating with Ca in bovine trypsin were exchanged for another amino acids in WP-T (His) and AC-T (His and Glu), respectively, and the contents of negative charged amino acids at their Ca-binding regions were lower than those of tropical-zone fish and bovine trypsins. Therefore, it was considered that these structural characteristics of WP-T and AC-T are closely related to their lower thermostability. [ABSTRACT FROM AUTHOR]

cDNA clone encoding trypsin (AG-T) was isolated from the pyloric ceca of cold-adapted fish, arabesque greenling ( Pleurogrammus azonus). The cDNA was composed of 892 bp with an open reading frame of 729 bp at nucleotide positions 25-753. Similar to all the known trypsin, the AG-T seemed to be synthesized as preproenzyme that contains a hydrophobic signal peptide, an activation pentapeptide and a mature trypsin of 222 amino acid residues. The AG-T also completely conserved the major structural features common to trypsin such as the catalytic triad (His57, Asp102, and Ser195), the obligatory Asp189 and twelve Cys residues. On the other hand, the AG-T possessed the deletion of Tyr151 and substitution of Pro152 for Gly in the autolysis loop when aligned with the sequence of tropical-zone fish and bovine trypsins. In addition, Val75 concerned in a combination with calcium ion was exchanged for Ala in the AG-T, and the content of positively charged amino acid residues at the calcium-binding site of the AG-T was three times higher than those of tropical-zone fish trypsins. Moreover, the ratio between charged and hydrophobic amino acid residues in the N-terminal region of the AG-T was also higher than those of temperate-zone fish and tropical-zone fish trypsins. Such structural properties of the AG-T would contribute to its low thermostability. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines the antioxidative ability of chicken myofibrillar protein. It states that chicken breast muscle was incubated in several concentrations of glucose or maltose to achieve glycosylated chicken protein. Meanwhile, the changes in the thermal stability and solubility during the experiment are also discussed.

Trypsin from the pyloric ceca of masu salmon ( Oncorhynchus masou) cultured in fresh water was purified by a series of chromatographies including Sephacryl S-200, Sephadex G-50 and diethylaminoethyl cellulose to obtain a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS–PAGE) and native PAGE. The molecular mass of the purified trypsin was estimated to be approximately 24,000 Da by SDS–PAGE. The enzyme activity was strongly inhibited by phenylmethylsulfonyl fluoride, soybean trypsin inhibitor, and N- p-tosyl- l-lysine chloromethyl ketone. Masu salmon trypsin was stabilized by calcium ion. The optimum pH of the masu salmon trypsin was around pH 8.5, and the trypsin was unstable below pH 5.0. The optimum temperature of the masu salmon trypsin was around 60°C, and the trypsin was stable below 50°C, like temperate-zone and tropical-zone fish trypsins. The N-terminal 20 amino acid sequence of the masu salmon trypsin was IVGGYECKAYSQPHQVSLNS, and its charged amino acid content was lower than those of trypsins from frigid-zone fish and similar to those of trypsins from temperate-zone and tropical-zone fish. In the phylogenetic tree, the masu salmon trypsin was classified into the group of the temperate-zone fish trypsin. [ABSTRACT FROM AUTHOR]

Trypsin inhibitor was purified from the viscera except for the hepatopancreas of Japanese common squid (Todarodes pacificus ) by gel filtration and anion-exchange chromatography. Final inhibitor preparation was homogeneous as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its molecular weight was estimated to be approximately 6,000 Da. The N -terminal amino acid sequence of the squid trypsin inhibitor was determined as ANEATXVYKGKTYKKGEGF. The purified inhibitor was heat stable up to 150 min at 80C at pH 8.0. The inhibitory activity was also retained at pH 2.0 and 37C for 180 min. The squid trypsin inhibitor was active against walleye pollock trypsin as well as porcine pancreatic trypsin. The squid trypsin inhibitor showed hypoglycemic effect on blood glucose levels of GK rats, a model of type 2 diabetes. PRACTICAL APPLICATIONS In this study, we purified a trypsin inhibitor from the viscera except for hepatopancreas of the Japanese common squid ( Todarodes pacificus). The squid trypsin inhibitor was acid and heat stable peptide. So, it was thought that the squid trypsin inhibitor is useful for biochemical regent and medicine of acute inflammation of human pancreas like soybean trypsin inhibitor and bovine aplotinin. Moreover, the squid trypsin inhibitor showed hypoglycemic effect on blood glucose levels of GK rats, a model of type 2 diabetes. Therefore, it may be useful for prevention of diabetes. [ABSTRACT FROM AUTHOR]

A highly viscous polysaccharide solution was extracted from Gagome Kjellmaniella crassifolia in 20°C water. The eluted sugar concentration was 0.16%, and the extracted carbohydrates consisted of fucoidan, laminaran, and alginate at an approximately ratio of 8.2:0.8:1.0. An increase in the extraction temperature resulted in a less viscous solution, even though the amount of eluted sugar was higher than that obtained at a lower temperature. The most viscous extraction solution was obtained at a neutral pH, with a more acidic or alkaline extraction solution being a less viscous. When the highly viscous polysaccharide solution was heated, the viscosity decreased markedly with increasing temperature. The viscosity of the polysaccharide solution increased after dialysis against water and decreased with the addition of either KCl or NaCl. However, the viscosity was recovered to previous levels by following re-dialysis against water. The removal of divalent cations by EDTA and the re-addition using CaCl2 or MgCl2 also caused reversible changes to the viscosity. These characterizations will be useful for widespread applications of viscous K. crassifolia polysaccharides. [ABSTRACT FROM AUTHOR]

A feasibility study was carried out to determine whether water-soluble salmon meat could be manufactured by conjugating a glycosyl unit using the Maillard reaction. Spawned out salmon meat was washed, mixed with alginate oligosaccharide (AO) and sorbitol, lyophilized, and then heated at 60°C and 5–95% relative humidity (RH) to introduce AO (the mean degree of polymerization was six) into the myofibrillar proteins through the Maillard reaction. The reaction progressed with an increase in the reaction humidity and the amount of AO bound to the protein reached >150 μg/mg at RH 65 and 90%. However, the protein glycosylation under high humidity impaired protein solubility and the meat protein became effectively water-soluble with the conjugation with AO at reaction conditions of 60°C and RH 35%. The improved characteristics of the meat protein were highly stable at room temperature. Further, the water-soluble protein can be prepared from the frozen salmon meat stored at −25°C for 60–90 days. These results indicate that protein glycosylation has strong potential for use with spawned out chum salmon. The suppression of protein denaturation during processing is important to obtain the high water-soluble meat protein. [ABSTRACT FROM AUTHOR]

Myosin rod regions prepared from carp Cyprinus carpio dorsal muscle and scallop Pecten yessoensis striated adductor muscle were non-enzymatically reacted with glucose (glycation), and the changes in the filament-forming ability and the size distribution of the rod filaments during glycation were examined to discuss the molecular mechanism of the water solubilization of myosin molecules under physiological conditions. Both myosin rods became solubilized in 0.1 M NaCl (pH 7.5), and their filament-forming ability was weakened with the progress of glycation. The size of the insoluble filaments of the myosin rods was diminished with an increase in the solubility under physiological conditions, and glycated myosin rods finally existed as monomers in 0.1 M NaCl (pH 7.5). These results supported the hypothesis that the water solubilization of myosin by glycation was caused by the loss of the filament-forming ability of myosin molecules. Water solubilization seemed to occur through the same molecular mechanism regardless of the species, whereas the scallop myosin rods required a much larger number of lysine residues reacted with glucose to collapse the insoluble filaments, in contrast to the carp myosin rods. [ABSTRACT FROM AUTHOR]

Carp myosin was conjugated with alginate oligosaccharide (AO) through the Maillard reaction under low relative humidity, and the functional properties of the myosin-AO conjugate were investigated to clarify the role of myosin in the functional improvement of fish myofibrillar proteins (Mf) by the glycosylation. The findings were as follows. First, myosin became highly solubilized at lower NaCl concentrations by conjugation with AO and NaCl-dependence of the solubility was lost when>12% of the available lysine residues were reacted with AO and 50 µg/mg of AO was attached to myosin. Second, the thermal stability of myosin was effectively improved by conjugation with AO. Heat-treatment at 50°C for 6 h has no effect on the solubility of the myosin-AO conjugate regardless of the NaCl concentration. Third, the improved functionalities of myosin conjugated with AO remained even at a nearly isoelectric point. The improving effect of AO-conjugation on the characteristics of myosin was almost the same as Mf reacted with AO. Therefore, it is apparent that that improved functionalities of the glycosylated Mf reflect the functional changes of myosin. [ABSTRACT FROM AUTHOR]

Carp and scallop myosin and their subfragments (S-1 and rod) were reacted with glucose to investigate the effect of non-enzymatic glycosylation on the functionality of myosin. The filament-forming ability of the myosin rod diminished with the progress of non-enzymatic glycosylation and myosin became soluble in 0.1 M NaCl. The inhibition of the self-assembly of myosin molecules occurred chemically as a result of the increase in negative charge repulsion among myosin molecules and, further, physically as a result of the introduction of the glycosyl units into the surface of the rod region. [Copyright &y& Elsevier]

Myofibrillar protein (Mf) of scallop muscle was reacted with various concentrations of glucose at 50°C and different relative humidities (RH 5–95%), and the change in solubility of Mf in low- and high-ionic-strength media was investigated. When the lyophilized Mf-glucose mixture (Mf : glucose = 1 : 18) was reacted at RH 5% and RH 35%, the solubility of Mf in 0.1 M NaCl increased markedly and almost equaled the solubility in 0.5 M NaCl. However, the improvement of the solubility in 0.1 M NaCl diminished at RH 65% and almost disappeared at RH 95%. The suppression of the solubility at RH 65% and RH 95% was mainly caused by the loss of the intrinsic salt-solubility of myosin, regardless of the degree of the Maillard reaction. The loss of the salt-solubility of myosin during the reaction with glucose was effectively suppressed by controlling the relative humidity at less than 35% and increasing the glucose concentration to more than 0.08 mol/g H2O. These results indicate that the improvement of the solubility of Mf in a low-ionic-strength medium by the Maillard reaction with glucose is closely related to the salt-solubility of myosin, and the relative humidity and the glucose concentration are important factors in suppressing myosin heat denaturation. [ABSTRACT FROM AUTHOR]

SUMMARY: Japanese common squid meat was heat-treated at 80°C for 1 min, cured with 1.0 M sorbitol solution (pH 7.0) at 4°C for 18 h, and dried further at 30°C (60% relative humidity) for 16 h. Osmotic dehydration during the sorbitol curing process and slow moisture vaporization at the initial drying period were observed regardless of the heat denaturation of muscle protein. Simultaneously, lowering the amount of moisture vaporized in the falling rate of the drying period caused a shortening of the total drying time. Furthermore, the shear force of the dried product from heat-treated meat was kept at a lower value by sorbitol curing, although the suppression effect of sorbitol on the hardening of dried meat was lost by protein denaturation. These results are useful for understanding the role of sorbitol in reducing drying time and in eliminating excess hardening of dried squid products. [ABSTRACT FROM AUTHOR]

Atka mackerel (Am) and Japanese common squid (Sq) meats were cured in 0.5-- 1.5 M sorbitol solutions (pH 7.0) and dried at 30C (relative humidity, 60%), and the effect of sorbitol on the moisture transportation and textural change during the curing and drying processes was inves-tigated. With an increase in sorbitol permeated through samples, the moisture contents decreased by 52% (Am) and 42% (Sq) by curing in 1.5 M sorbitol solution. When the cured meats were dried, slow moisture vaporization occurred at the initial drying period, and the critical moisture content sig-nificantly decreased with an increase in the sorbitol content of the cured meats. Further, the hard-ening of the dried products was effectively suppressed by sorbitol curing. These effects of sorbitol would contribute to the reduction of drying time and particularly the elimination of the excess hard-ening of dried fish products. [ABSTRACT FROM AUTHOR]

Presents a study describing the suppression of the breakdown of myosin heavy chain by the addition of cysteine protease inhibitors or bovine plasma powder when salted surimi paste of chum salmon was incubated at 20-60 degrees. Importance of gel forming ability for good quality surimi-based products; No evidence of suwari and no myosin heavy chain cross-linking.

The article discusses the results of a study on the characterization of fish myofibrillar protein by conjugation with alginate oligosaccharide prepared using recombinant alginate lyase. The researchers found that the production of alginate lyase using genetically modifies Escherischia coli was superior to the purification of alginate lyase from a culture medium if Pseudoalteromonas elyakovii on production efficiency.