Distribution of Cathepsin D Activity between Lysosomes and a Soluble Fraction of Marinating Brine

Abstract

This paper is the first ever to describe the phenomenon of bimodal distribution of cathepsin D in the lysosomal and soluble fractions of brine left after herring marinating. Up to 2 times higher cathepsin D activity was observed in the lysosome fraction. Activity of cathepsin D in brine increased according to the logarithmic function during low frequency-high power ultrasounds treatment or according to the linear function after multiple freezing-thawing of brine. Activity enhancement was achieved only in the brine devoid of lipids and suspension. Study results show also that measurement of lysosomal cathepsin D activity in the marinating brine requires also determining cathepsin E activity. Decreasing pore size of microfilter from 2.7 to 0.3 μm significantly reduced the lysosome content in the brine. The presence of lysosomes and the possibility of their separation as well as the likely release of cathepsins shall be considered during industrial application of the marinating brine, as new cathepsins preparations in fish and meat technology.

The reuse of brine to enhance the ripening of marine and freshwater fish resistant to marinating

“…Reused brine permeate contained non‐protein nitrogen (270 mg/100 mL), whereas activities of its aspartyl and cysteine proteases reached 0.55 and 0.82 U MCA , respectively. The microfiltration of brine was expected not only to reduce its microbiological contamination, but also to damage membranes of lysosomes and promote cathepsins activity (Szymczak, ). Results obtained with the reused brine are similar to these reported in our previous study (Szymczak et al ., ).…”

Recovery of cathepsins from marinating brine waste

“…The use of 100-kDa filter allowed recovery of 73% aspartyl cathepsins and 77% cysteine cathepsins from the crude brine. In turn, the recovery of over 100% of the proteolytic activity results from damage membrane of lysosomal by pressure and the release of cathepsins outside (Szymczak, 2016b;Szymczak & Lepczy nski, 2016). It is linked with reduction of cathepsins losses to permeate from 30-40% to 0-17%.…”

“…It is linked with reduction of cathepsins losses to permeate from 30-40% to 0-17%. The pressure during centrifugation was, probably, either too low and/or lasted too short timescale to allow two to threefold increase in cathepsins activity in the retentate, as in the case of the sonicated brine (Szymczak, 2016b). It is due to a higher molecular weight of cathepsin D and E (ca.…”

“…40 and 100 kDa, respectively), compared to cathepsins B and L (20-30 kDa). In turn, the recovery of over 100% of the proteolytic activity results from damage membrane of lysosomal by pressure and the release of cathepsins outside (Szymczak, 2016b;Szymczak & Lepczy nski, 2016). At the beginning of ultrafiltration, the hydrostatic pressure of the centrifuged brine was up to 1-2 MPa, but along with retentate concentration the pressure was decreasing to ca.…”

“…The preliminary microfiltration (2.7um) facilitates ultrafiltration and reduces the activity of lysosomal cathepsin D in the brine only by 7% (Szymczak, 2016b). The pressure during centrifugation was, probably, either too low and/or lasted too short timescale to allow two to threefold increase in cathepsins activity in the retentate, as in the case of the sonicated brine (Szymczak, 2016b). The effect of activity increase above 100% and differences between the analysed retentates could also be in part induced by the removal of naturally occurring cathepsin inhibitors such as cystatins with the molecular weights of 10-15 kDa and/or products of protein hydrolysis (Benjakul et al, 1997;Sentandreu et al, 2002).…”