Proteolysis of noncollagenous proteins in sea cucumber, Stichopus japonicus, body wall: Characterisation and the effects of cysteine protease inhibitors

Proteolysis of noncollagenous proteins in sea cucumber, Stichopus Japonicus, body wall (sjBW) was investigated. The proteins removed from sjBW by SDS and urea extraction were mainly noncollagenous proteins with molecular weights about 200 kDa (Band I) and 44 kDa (Band II), respectively. Band I and Band II were identified as major yolk protein (MYP) and actin, respectively, from holothurian species by liquid chromatography–mass spectrometry (LC–MS/MS) with significant scores. Based on TCA-soluble oligopeptide assay, the optimum proteolysis condition of noncollagenous proteins was at 46.3 °C and pH 6.1, by response surface methodology. The proteolysis of MYP, and actin, was partially inhibited by cysteine protease inhibitors, including Trans-epoxysuccinyl-l-leucyl-amido (4-guanidino) butane (E-64), iodoacetic acid, antipain and whey protein concentrate. These results suggest that cysteine proteases are partially involved in the proteolysis of noncollagenous proteins in body wall of sea cucumber, S. japonicus.     

Autolysis of goatfish (Mulloidichthysmartinicus) mince: Characterisation and effect of washing and skin inclusion

Autolysis of goatfish mince and washed mince incubated at different temperatures (30–70 °C) was investigated. The highest autolytic activity was generally observed in mince and washed mince at 60 °C as evidenced by the highest trichloroacetic acid (TCA) soluble peptide content and the greatest disappearance of myosin heavy chains (MHCs). Autolysis of both mince and washed mince was maximised at pH 4, and lower autolytic activity was observed at pH 7. trans-epoxysuccinyl-l-leucyl-amido (4-guanidino) butane (E-64) showed the greatest inhibition of autolysis at pH 4, showing that at least one cysteine protease was active in goatfish muscle. Nevertheless, soybean trypsin inhibitor effectively inhibited the autolysis at neutral pH (pH 7), suggesting that goatfish muscle also contained at least one serine protease. Generally, autolysis of mince was more pronounced than that of washed mince, indicating that washing could lower the autolytic activity of mince. In the presence of skin, a higher autolysis was obtained with the goatfish mince. Therefore, both sarcoplasmic and myofibril-associated proteases in muscle as well as the contamination of skin likely contributed to the degradation of muscle proteins of goatfish.     

鱿鱼肝脏蛋白酶的鉴定及组织蛋白酶L的分离纯化

鱿鱼肝脏含有丰富的蛋白酶,为利用其内源蛋白酶进行可控的酶解,本研究以鲤鱼肌原纤维蛋白为底物对鱿鱼肝脏内源蛋白酶的种类和性质进行了研究。反应体系中添加E-64、1,10-菲啰啉和苯甲基磺酰氟(phenylmethylsulfonyl?fluoride,PMSF)后,肌球蛋白重链(myosin?heavy?chain,MHC)的降解得到了显著抑制,确定了鱿鱼肝脏含有金属类、半胱氨酸类、丝氨酸类3类蛋白酶。半胱氨酸类蛋白酶热稳定性最好,在50℃以上仍然具有较大活性,可将肌原纤维蛋白酶解成小分子质量的降解产物。利用特异性底物对半胱氨酸蛋白酶种类进行鉴定发现,该酶只酶解Z-Phe-Arg-MCA,添加亮抑酶肽后相对酶活性为0%,添加E-64相对酶活性仅存0.6%,初步确定鱿鱼肝脏中的半胱氨酸蛋白酶主要为组织蛋白酶L。最后,通过硫酸铵沉淀、离子交换层析、凝胶过滤对组织蛋白酶L进行分离纯化,在电泳上得到了分子质量约为25?kD单一条带。     

Purification and characterization of cathepsin B from the gut of the sea cucumber (<Emphasis Type="Italic">Stichopus japonicas</Emphasis>)

Cathepsin B from the gut of sea cucumber (Stichopus japonicas) was purified 81-fold with a 3% recovery by ammonium sulfate fractionation and a series chromatography on DEAE Sepharose CL-6B, Sephadex G-75, and TSK-Gel 3000 SWxl. The purified protein appeared as a single band on Native-PAGE but showed 2 bands of 23 and 26 kDa on SDS-PAGE. The optimum activity was found at pH 5.5 and 45°C. The enzyme was stable at pH 4.5–6.0 and the thermal stability was up to 50oC. The enzyme was strongly inhibited by E-64, iodoacetic acid, and antipain, demonstrating it is a cysteine protease containing sulfhydryl groups. Cu²⁺, Ni²⁺, and Zn²⁺ could strongly inhibit the enzyme activity. The amino acid sequences of the purified enzyme were acquired by mass spectrometer, which did not show any homology with previously described cathepsins, suggesting it may be a novel member.     

Utilization of oryzacystatin for regulating the ripening of squid shiokara, a traditional Japanese salted and fermented seafood

Shiokara is a fermented seafood composed of sliced squid mantle muscle ripened with fresh squid liver. Preliminary sensory evaluation by using the ranking test revealed that the hardness of squid muscle in shiokara was reduced within 7 d of ripening. During the process of ripening, muscle proteins were digested by proteinases present in squid liver. The degradation of paramyosin and myosin heavy chain was observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The hardness of squid mantle muscle in shiokara was reduced with the degradation of paramyosin and myosin heavy chain. This degradation was mainly caused by E-64-sensitive cysteine proteinases. To control the hardness of shiokara, we used rice seed oryzacystatin, which suppresses proteolysis by papain-like cysteine proteinases. When oryzacystatin was added 4 d after the start of shiokara ripening, the muscle protein degradation stopped, without further muscle softening. These results show that oryzacystatin is useful to control the ripening of shiokara by regulating its hardness.     

刺参2 种天冬氨酸蛋白酶的酶学性质及其对自溶的影响

对刺参体内2?种天冬氨酸蛋白酶——组织蛋白酶D（cathepsin?D,Cat?D）和组织蛋白酶E（Cat?E）的酶学性质进行探讨,并考察两者可能在刺参自溶中的参与作用。先用Tris-HCl缓冲溶液提取刺参体壁中的粗酶,采用特异性荧光底物法测定Cat?D和Cat?E的酶学性质。结果表明,Cat?D和Cat?E的最适pH值分别为5.0和4.0,分别在60?℃和40?℃呈现最大酶活性,两者在20～40?℃活性均较为稳定。Zn2＋、Cu2＋、Fe2＋、Fe3＋、Mn2＋可抑制Cat?D的活性,抑制率分别为86%、76.3%、29.2%、56.5%和48.5%。Fe3＋、Fe2＋、Cu2＋可抑制Cat?E的活力,抑制率分别为99.1%、82.2%和28.6%。Pepstatin?A、Z-Leu-Leu-Leu-H、苯甲基磺酸氟、1,10-菲啰啉能够抑制两者活性,抑制率分别约为98%～99%、65%～78%、30%～35%、19%～23%。二硫苏糖醇、L-Cys和乙二胺四乙酸则可将两者活性分别提升30.4%～31.1%、7.58%～9.64%、6.6%～7.9%。结果表明,刺参Cat?D和Cat?E为2?种具有一定金属离子敏感性和依赖性的天冬氨酸蛋白酶,其活性中心有丝氨酸和半胱氨酸参与其活性调节,且两者很有可能参与刺参自溶过程中蛋白质的降解。     

Combination of NMR and MRI Techniques for Non-invasive Assessment of Sea Cucumber (<Emphasis Type="Italic">Stichopus japonicas</Emphasis>) Tenderization During Low-Temperature Heating Process

The purpose of this study was to develop and test the combination of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) method to assess the proton changes of sea cucumber body wall during low-temperature heating process. NMR relaxometry and MRI measurements indicated a significant proton change in the internal structure for sea cucumber body wall when the heating temperature increased from 45 to 55 °C. Differential scanning calorimetry (DSC) analysis revealed that the denaturation temperature of sea cucumber body wall was in the range of 45–55 °C with an endothermic peak at 51 °C, which is in accordance with the result observed in NMR and MRI. Rheological study showed similar trend to the DSC thermogram. The band change in amide I region of Fourier transform infrared (FTIR) spectra indicated the decrease in α-helix content and possible formation of other secondary structures. Scanning electron microscopy (SEM) further confirmed that the low-temperature heating did induce microstructure changes. The analysis of the Ringer?s soluble fraction (RSF), enzyme-labile fraction (ELF), and total unaltered fraction (TUF) for sea cucumber body wall during low-temperature heating provided more detailed information on the cause of structure change observed in NMR and MRI. The NMR parameters were highly correlated with the rheology storage modulus (G′), relative enzymatic assay parameters, RSF, ELF, and TUF. All these results demonstrated that it could be possible to use NMR and MRI to assess sea cucumber tenderization during low-temperature heating process.     

Inhibition of protease activity. Part 1. The effect on tenderness and indicators of proteolysis in ovine muscle

To examine the effect of particular enzyme groups on tenderness specific cysteine protease inhibitors were injected into muscle early post-mortem. The protease enzyme inhibitor E-64 was injected into the m. longissimus thoracis et lumborum (LTL) on the right side of 12 lamb carcasses within 15 min of death and in another 12 carcasses with the protease inhibitor Z-Phe-Ala-CHN(2). The left LTL (control) was injected with saline (0.25 M NaCl). To create variation in the rate of pH decline alternate carcasses were electrically stimulated (low voltage). The LTL was divided into cranial and caudal portions and aged for 1 or 2 days. Muscle samples at 1 day post-mortem were used for measurement of osmolality and sarcomere length (n=48), and others at 1 and 2 days post-mortem for shear force determination (n=96). The myofibrillar fragmentation index (MFI) was determined on samples taken at pH 6.2 and 1 and 2 days post-mortem (n=144). Other muscle samples were obtained at death, pH 6.2 and 6.0 and then at 1 and 2 days post-mortem (n=215). These samples were used for determination of protein solubility and the concentration of free amino acids. Stimulation caused a faster (P<0.05) decline in pH. There was no effect of stimulation (P>0.05) on shear force values, but injection of inhibitor and ageing both had effects (P<0.001). The inhibitor E-64 prevented any improvement in tenderness with ageing, whereas the inhibitor Z-Phe-Ala-CHN(2) and the control samples showed a similar ageing response. In the latter two treatments there was an average reduction of 1 kg in shear between 1 and 2 days post-mortem, whilst the inhibitor E-64 maintained shear force on average 2 kg higher than control samples. Injection and ageing had an effect on MFI (P<0.001) and there was an interaction (P<0.05) between stimulation and ageing for MFI, such that as stimulated muscle aged the rate of change of MFI was greater. There was an interaction between injection and ageing (P<0.05) for protein solubility such that samples treated with E-64 showed a minimal increase in protein solubility with ageing, whereas in samples treated with Z-Phe-Ala-CHN(2) and the control samples there was a significant increase. There was also an interaction between stimulation and ageing such that between sampling at pH 6.0 and 2 days post-mortem, stimulated muscle exhibited greater solubility (P<0.05). There were no effects (P>0.05) on the concentration of free amino acids. The evidence indicated that the cysteine proteases were responsible for post-mortem proteolysis and tenderisation, in particular the calpains, whereas the cathepsins (B and L) were unlikely to contribute to proteolysis and subsequent tenderisation in meat.     

Post mortemRelease of Fish White Muscle α-Actinin as a Marker of Disorganisation

α-Actinin release and its degradation from myofibrils Z-line were studied in post mortem white dorsal muscle from bass and sea trout stored at 4°C and 10°C. Using α-actinin specific antibodies, we show that this protein is rapidly released within the first 24 h for the two species, and reaches a plateau within 4 days. Proteolysis take place very rapidly in bass muscle yielding 80 and 40 kDa fragments from α-actinin as major bands of proteolysis. Sea trout muscle is more resistant, and muscle stored at 4°C is not significantly α-actinin degraded even 10 days after death. In the case of sea trout muscle stored at 10°C, an increasing quantity of 80 and 40 kDa fragment can be observed after the third day. These results show that release and proteolysis of α-actinin are time- and temperature-dependent processes that take place at the early stages of fish storage. Furthermore, we observed that proteolysis of α-actinin seems to be dependent on fish species. In both species studied, the early release of α-actinin comes before the degradation of released molecules, and appears as a biphasic process throughout the disorganisation of post mortem muscle in fish cold-stored above 0°C.     

Proteolysis and Its Control Using Protease Inhibitors in Fish and Fish Products: A Review

Texture is one of the food quality attributes affecting the consumer's acceptability and the market value. Fish and shellfish undergo weakening or softening of muscle, particularly during extended storage under inappropriate conditions. The phenomenon is governed by endogenous proteases, both digestive and muscle proteases. Proteases present in the gastrointestinal tract that leach out to muscle tissue can induce proteolysis of myofibrillar and collagenous proteins. Furthermore, the muscle proteins present in gels fabricated from fish or shellfish meat also encounter degradation during thermal processing. Endogenous heat‐activated proteases strongly bind to muscle proteins and are activated during heating, thereby degrading myofibrillar proteins, which are abundant in muscle tissue. This deterioration of the proteins directly leads to a weakened gel with poor water‐holding capacity. Both cysteine and serine proteases are responsible for the degradation of myofibrillar proteins in several aquatic animals. Effective pretreatment of fish and shellfish, as well as the use of food‐grade protease inhibitors (PIs), have been implemented to inactivate endogenous muscle and digestive proteases. For this review, proteolysis of muscle proteins and its control by food‐grade PIs are revisited. Improved and effective lowering of proteolysis should be gained, thereby maintaining the quality of fish and their products.     

Heat-activated proteolysis in lizardfish (Saurida tumbil) muscle

Autolysis of lizardfish mince and washed mince during heating at elevated temperatures was studied. Higher degradation of myosin heavy chain (MHC) was generally observed in mince, compared to washed mince. The highest autolysis was observed at 65 and 60 °C for mince and washed mince, respectively. Autolysis was extended as the incubation time increased by the result of the decrease in MHC band intensity on SDS-PAGE and the increase in TCA-soluble peptides. Autolysis of washed mince was markedly inhibited by E-64 and soybean trypsin inhibitor, suggesting that myofibril-associated proteinases were both cysteine and serine proteinases. Sarcoplasmic proteinase was characterized to be heat-activated alkaline proteinase, which had the optimal pH and temperature of 8.0 and 65 °C, respectively. The preteinase was inhibited by E-64 and activated by reducing agents, which was one of the characteristics of cysteine proteinase. Therefore, endogenous sarcoplasmic and myofibril-associated proteinases play an important role in degradation of myofibrillar proteins of lizardfish during heat-induced gelation, which results in gel weakening.     

Synergistic interaction of <Emphasis Type="Italic">Auricularia auricula</Emphasis>-<Emphasis Type="Italic">judae</Emphasis> polysaccharide with yam starch: effects on physicochemical properties and in vitro starch digestibility

Thermal stable polysaccharides from Auricularia auricula-judae (AP) have unique molecularstructures and multiple bioactivities. The effects of AP on the physicochemical properties and in vitro starch digestibility of yam starch (YS) were studied. The addition of AP induced a significant increase in the swelling power, solubility, mean volume diameter and adhesiveness as well as a dramatic decrease in the hardness and gumminess (p?<?0.05). AP showed a strong suppressive effect on in vitro starch digestibility. Higher modulus (G′, G″) and stiffness parameters (A_α), and lower order of relaxation function (α), were observed in oscillatory rheological measurements, indicating that the gels were more elastic-like and had higher pseudoplasticity in the presence of AP. Furthermore, AP remarkably decreased the syneresis and storage modulus (G′), and also retarded the retrogradation process of YS gel at 4°C, revealing a synergistic interaction between AP and YS, which could also be demonstrated by scanning electron microscopy.     

Identifying the geographical origin of protected sea cucumbers (<Emphasis Type="Italic">Apostichopus japonicus</Emphasis>) in China using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR)

Dalian sea cucumber, Yantai sea cucumber, and Weihai sea cucumber, which belong to Apostichopus japonicus, are protected as geographical indications in China based on their high nutritional values and medical propertys. The 26 samples, including Dalian sea cucumbers (9 samples) in Liaoning province, Yantai sea cucumbers (9 samples), and Weihai sea cucumbers (8 samples) in Shandong province, were individually collected from the designated geographical sea areas and the genetic relationships and DNA polymorphisms were evaluated by random amplified polymorphic DNA technology and gene segments sequencing. The RAPD dendrogram showed that the genetic diversity of the three types of sea cucumbers was rich. The neighbor-joining tree shows that the genetic relationship of the samples from the adjacent sea areas is closer. It demonstrates that the gene characteristics of sea cucumbers from different sea areas were obvious and the genetic diversity analysis by RAPD-PCR can be used as a rapid method for geographical discrimination.     

Characterisation of proteolytic enzymes from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii)

BACKGROUND: Fresh water prawn in Thailand is widely consumed due to its delicacy. During postmortem handling and storage, prawn meat becomes soft and mushy, probably as a result of indigenous proteases. Therefore, an understanding of prawn proteases associated with the degradation of muscle proteins from fresh water prawn could pave the way for prevention of such a phenomenon during extended storage. RESULTS: Proteolytic enzymes in the crude extract (CE) from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) were characterised. CE from muscle exhibited the highest hydrolytic activities towards haemoglobin at pH 5 and 50 °C, while that from hepatopancreas had the highest activity on casein at pH 7 and 60 °C. Based on inhibitor study, cysteine protease and serine protease were dominant in CE from muscle and hepatopancreas, respectively. CE from muscle rarely hydrolysed natural actomyosin (NAM), but could not degrade pepsin‐soluble collagen (PSC). Conversely, NAM and PSC were susceptible to hydrolysis by CE from hepatopancreas as evidenced by the marked decreases in band intensity. Activity staining using haemoglobin, casein and gelatin as substrates revealed that no proteolytic or gelatinolytic activity was observed in CE from prawn muscle, while CE from hepatopancreas exhibited pronounced hydrolytic activities towards all substrates. CE from muscle showed calpain and cathepsin L activities but CE from hepatopancreas mainly exhibited tryptic and chymotryptic activities. CONCLUSION: Serine proteases, mainly trypsin‐like or chymotrypsin‐like, from hepatopancreas were probably responsible for the softening of prawn meat during postmortem storage via the degradation of both muscle and connective tissues. Copyright © 2010 Society of Chemical Industry     

Post-mortem degradation of myosin heavy chain in intact fish muscle: Effects of pH and enzyme inhibitors

Fish muscle is rapidly degraded during post-mortem storage, due to proteolytic enzymes acting probably both on muscle cells and connective tissue. In this work we have developed a model system which may be used to study the enzymatic degradation occurring in intact post-mortem fish muscle. Degradation of myosin heavy chain (MHC) was monitored in muscle with pH adjusted to 6.05, 6.3 and 6.9 and in the presence of the enzyme inhibitors PMSF, EDTA, phenanthroline, pepstatin A, antipain, E-64 and the cysteine proteinase activator dithiothreithol (DTT). After storage, myofibrillar proteins were isolated and MHC-specific antibodies used to study the degradation in the different samples. MHC from muscle with pH 6.05 and 6.3 was degraded, while no severe degradation was observed at pH 6.9. Introduction of enzyme inhibitors into the muscle tissue clearly showed that mainly cysteine and aspartic proteinases are responsible for the in situ MHC degradation. This is supported by the severe breakdown of MHC in the muscle samples containing DTT.     

Effect of <Emphasis Type="Italic">Monascus</Emphasis> sp. as an adjunct starter on physicochemical properties and proteolysis in semi-hard cheeses during ripening

Two kinds of semi-hard cheeses, with Monascus purpureus and without M. purpureus, were manufactured, and effects of M. purpureus on physicochemical properties and proteolysis were evaluated during 36 days of ripening. Addition of M. purpureus changed the microbial survival and showed no significant effect on physicochemical properties of the cheeses, including dry matter and pH. Regardless on the rind or in the core, the indices of proteolysis had no significant difference (p>0.05), whereas there were significant differences of total free amino acid (FAA) and individual FAA between cheeses; this indicated that M. purpureus had no significant effect on the primary proteolysis, but affected the content and ratio of individual FAAs during maturation. Electrophoretic analysis showed strong degradation of α_s1-casein in the core and on the rind of cheeses, while β-casein was highly degraded on the rind but less in the core. Thus, Monascus spp. might have a potential application in the manufacture of cheeses.     

Effect of matrix metalloproteinase on autolysis of sea cucumber Stichopus japonicus

To investigate the relationship between matrix metalloproteinase (MMPs) and autolysis of sea cucumber Stichopus japonicus, the dermis homogenate was incubated at 25°C to induce autolysis. EDTA Na₂ and 1,10-phenanthroline were used to verify the effect of MMPs on autolysis, which was measured by soluble protein and protein pattern. Soluble protein level increased during a 6-h autolysis process. SDS-PAGE demonstrated obvious protein degradation with the concomitant occurrence of degradation products. The above two indicators could be inhibited significantly by EDTA Na₂ and 1,10-phenanthroline, indicating that MMPs might play a significant role in autolysis of sea cucumber.     

刺参体壁胰/类胰丝氨酸蛋白酶的性质及其在自溶中的作用

以刺参体壁中丝氨酸蛋白酶为研究对象,对其部分酶学性质及其与刺参自溶的关系进行研究。采用Tris-HCl缓冲溶液提取、硫酸铵盐析、透析及超滤获得刺参体壁粗酶液。结果显示,以Boc-Phe-Ser-Arg-MCA为底物时,粗酶液的丝氨酸蛋白酶活力最高;以其为底物,测得该类蛋白酶在pH值为6.2和8.5时呈现较强酶活力峰值,两者最适温度范围均为50～55?℃;Cu2＋、Fe3＋、Pb2＋、Zn2＋强烈抑制该酶的活性,Ca2＋可提高该酶活力;邻菲咯啉、乙二胺四乙酸以及半胱氨酸修饰剂均能够部分抑制该酶活力。4-(2-氨乙基)苯磺酰氟盐酸盐、苯甲基磺酰氟、Na-对甲苯磺酰-L-苯丙氨酸氯甲基酮、(3S)-7-氨基-1-氯-3-磺酰氨基-2-庚酮盐酸盐、大豆胰蛋白酶抑制剂能够显著抑制蛋白酶的活力以及自溶过程中可溶性蛋白、三氯乙酸可溶性多肽的生成。上述结果表明,刺参体壁中存在至少2?种具有一定的金属离子依赖性的胰/类胰丝氨酸蛋白酶,其活性中心或底物识别位点可能有半胱氨酸的参与,该类蛋白酶很可能参与刺参自溶过程中蛋白质的降解。     

Biochemisch-technologische Studien über die Naßverarbeitung von Mais. 6. Mitteilung. Untersuchung des proteolytischen und lipolytischen Enzymsystems des Maises

Biochemical-Technological Studies on Wet-Processing of Maize. Part 6. Examination of the Proteolytic and the Lipolytic Enzyme System of Maize. 1. Maize lipase shows the following optima: pH-optimum about 8,0, temperature optimum about 40°C. 2. The efficiency of the proteolytic enzymes covers a broad pH-range (2,0–9,0). Efficiency reaches a distinct maximum between pH 3,5 and 4,5 and a weaker maximum at pH 8. Enzymes show high stability (45 °C). For proteolysis of the maize protein temperatures around 40 °C are the optimum. 3. Maize proteases are inactivated by 2 · 10⁻³ M potassium persulfate and 6 · 10⁻⁴ M potassium bromate; 6,5 · 10⁻³ M cysteine doubles activity. 4. SO₂-contents up to 0,1% cause an increase of proteolytic degradation with a maximum at 0,03%.     

蓝圆鲹肌肉组织蛋白酶B的纯化与性质分析

在鱼糜制品生产过程中,凝胶劣化现象是引起鱼糜品质下降的重要原因。研究表明,溶酶体中的内源性组织蛋白酶B会促进肌原纤维蛋白的降解,进而导致鱼糜凝胶劣化。迄今为止,多种鱼体肌肉中的组织蛋白酶B已有研究,但海水经济低值鱼蓝圆鲹中该酶的情况却尚未报道。本研究采用硫酸铵沉淀和柱层析相结合的方法,从蓝圆鲹肌肉中分离纯化得到分子量约为27ku的组织蛋白酶B。酶学性质结果显示,该酶最适温度和最适pH分别为55℃和5.5,半胱氨酸蛋白酶抑制剂E-64能有效抑制其活性。对肌原纤维蛋白的降解实验表明,在最适条件下,蓝圆鲹组织蛋白酶B对肌原纤维蛋白有一定的降解作用。因此,组织蛋白酶B参与肌原纤维蛋白的降解,更可能参与在低pH条件下鱼糜凝胶劣化。