Degradation of canine cardiac myosin and actin by cathepsin D isolated from homologous tissue

Cathepsin D and Its Effects on Myofibrillar Proteins: A Review

“…The effect of cathepsin D on myofibrillar proteins has been studied by several authors (Schwartz and Bird 1977;Ogunro et al 1979;Okitani et al 1981;Matsumoto et al 1983;Matsukara et u1. 1984;Elgasim et al 1985;Zeece et al 1986a).…”

“…Similarly, this enzyme has been proposed to play a significant role in the postmortem proteolysis process putatively associated with tenderization (Robbins thepsin D exists as several isomers with PIS in the range of 5.7 to 6.8. The pH optimum of cathepsin D is rather acidic (pH 3.0-4.5) which is typical for aspartyl enzymes, but it also exhibits a broad range of activity on muscle substrates (pH 3.0-6.0) (Schwartz and Bird 1977;Ogunro et al 1979).…”

“…Cathepsin D isolated from canine cardiac muscle had a molecular weight of 42,000 by gel filtration and was composed of two subunits of 32,000 and 14,000 daltons when examined by SDS-PAGE (Ogunro et al 1979;1980;. The issue of whether the enzyme consists of a single polypeptide chain or contains subunits has been a major source of debate.…”

The effect of calcium activated protease (CAF) and cathepsin D on bovine muscle myofibrils under varying conditions of pH and temperature

“…In general, it was concluded that cathepsin D was more effective in degrading myosin and actin than was cathepsin B . Other studies (Ogunro et al, 1979) have shown that cathepsin D isolated from cardiac muscle had similar activities toward myosin and actin as did the skeletal muscle enzyme except that the light chains of myosin also were degraded by the cardiac enzyme. Recently, it was shown that addition of cathepsin D to purified muscle proteins resulted in degradation of myosin heavy chains, tropomyosin, troponin T, troponin I, and alpha-actinin (Matsumoto et al, 1983).…”

“…The subunit molecular weights of porcine spleen cathepsin D reported by Puizdare and Turk (1981) were estimated to be 35,000 and 15,000 using the electrophoresis system described by Weber and Osborn (1969). Ogunro et al (1979Ogunro et al ( , 1982 found that cathepsin D purified from canine cardiac muscle had a native molecular weight of approximately 50,000 as measured by gel filtration. Canine cardiac cathepsin D was composed of two subunits with molecular weights of approximately 32,000 and 14,000 (Ogunro et al, 1980;Sameral et al, 1981) by SDS-PAGE.…”