α;₂‐Macroglobulin Inhibition of Endogenous Proteases in Fish Muscle

Abstract

Fig. 1-Effects of ␣ 2 -macroglobulin on chymotrypsin and cathepsin C activities using the synthetic substrates, BTEE, and Glyphe-NA. Each assay system contained 400 µg inhibitor. Activity measured as change in absorbance/min. Mean of three separate experiments. ABSTRACTKINETIC PARAMETERS for ␣ 2 -macroglobulin inhibition of selected proteases (collagenase, cathepsin D, trypsin and chymotrypsin) were determined along with the extent of inhibition of the corresponding fish muscle proteases. Protease inhibition by ␣ 2 -macroglobulin occurred in the presence of large macromolecular substrates but not in the presence of synthetic substrates. The inhibitor remained active at refrigerated temperatures (4-7ЊC). The ␣ 2 -macroglobulin did not have any inhibitory effects on proteases in intact fish muscle tissue possibly due to lack of penetration of the tissues, but showed various levels of inhibition of proteases in tissue homogenates. Inhibitor concentration of 0.1% per weight of tissue homogenate resulted in about 17% loss of proteolytic activity while 0.4% inhibitor concentration caused complete loss of protease activity.

Broad‐spectrum inhibition of proteolytic enzymes by allicin and application in mitigating textural deterioration of ice‐stored grass carp (Ctenopharyngodon idella) fillets

“…As for inhibitory effect on collagenase, allicin at 100 m m inhibited this enzyme by 57%, which was slightly lower than that demonstrated by epigallocatechin gallate which has been found to be an efficient edible inhibitor for collagenase with inhibitory ratio of about 80% (Saito et al ., ). Also, inhibitory effect of allicin on cathepsin D was 32% at 100 m m which was comparable to that for macroglobulin against cathepsin D observed by Ashie & Simpson (). Therefore, the results revealed the effective inhibition of allicin on endogenous enzyme in ice‐stored grass carp fillets.…”

Effect of Hydration Time and Salt Addition on Gelation Properties of Major Protein Additives

“…Weerasinghe and others (1996a) suggested that BPP and DEW had the highest rate of cysteine and serine proteinase inhibition, respectively. Protease inhibition by BPP might be due to ␣-macroglobulin (Ashie and Simpson 1996). The highest shear strain of Pacific whiting surimi was obtained with WPC at 4% (Weerasinghe and others 1996b).…”

Control of Endogenous Enzyme Activity in Fish Muscle by Inhibitors and Hydrostatic Pressure using RSM

“…We had previously noted that increasing inhibitor concentration in the homogenized fish tissue from 0.1% to 0.2% resulted in 50% reduction of residual protease activity. Increasing inhibitor concentration from 0.2% to 0.3% further reduced residual protease activity by only 9% (Ashie and Simpson, 1996b). Thus during storage, any residual inhibitor in the homogenate would inhibit the proteases, thereby preventing any increased activity upon reactivation.…”

“…This was further shown by the low correlation (r ϭ 0.30) between proteolysis and viscosity as compared to the high correlation (r ϭ 0.89) between firmness/elasticity and protease activity when intact fish tissues were subjected to hydrostatic pressure alone . Application of the inhibitor in intact muscle tissues, however, may be limited by its lack of penetration into intact tissues (Ashie and Simpson, 1996b).…”