The role of proteinase enzymes in the process of conversion of muscle to meat

Post mortem meat tenderization is a complex mechanism and unfortunately it has not been fully identified scientifically. It is known that endogenous proteinases have an important role in this mechanism. Detailed studies are being performed about the destructive effects of lysosomal proteinases and calcium dependent proteinases on the myofibrils and these are most common topics that are being investigated about meat tenderization processes by the scientists. The aim of this paper is to review the role of proteinase enzymes in the process of conversion of muscle to meat. .

Processing and Activation of Lysosomal Proteinases

Lysosomal proteinases are translated as preproenzymes, transferred through the Golgi apparatus as proenzymes, and localized in lysosomes as the mature enzymes. Pulsechase analyses and the immunoisolation of proenzymes or recombinant proenzymes are useful tools for analyzing this process, but the processing proteinases that participate in this pathway are largely unknown. Recently, we developed a new method for analyzing processing proteinases using Bafilomycin A1 and proteinase inhibitors. Here we summarize the recent progress including our results obtained using this method.

A Lysosomal Pepstatin-Insensitive Proteinase as a Novel Biomarker for Breast Carcinoma

Lysosomal proteinases play an important role in the turnover of intracellular proteins, and acidic proteinases such as cathepsin D are known to be increased in breast carcinoma. In the present study the activity of a newly discovered acidic lysosomal pepstatin-insensitive proteinase (CLN2p) was measured in breast tissues by the most sensitive and highly specific assay that we had developed for the diagnosis of late-infantile neuronal ceroid lipofuscinosis (LINCL) (2). Samples from eight normal subjects undergoing reductive mammoplasty and 200 patients with primary breast carcinoma were analyzed. The results suggest a two- to seventeen-fold higher CLN2p activity in tumors, which was significantly and positively correlated with already known breast cancer biomarkers such as levels of cathepsin D, estrogen receptor and progesterone receptor. These results suggest a diagnostic and prognostic potential for this novel acid proteinase in breast cancer.