engleski

Detection of cathepsin D in ewe milk

Milk contains about 70 indogene enzymes, while only twenty of them were researched. One of the less explored is the milk enzyme cathepsin D, located in the lysosomes, which are an integral part of the somatic cells. Most researches were conducted on bovine’s milk where it was determined four forms of cathepsin D: procathepsin D correspond to molecular masses of 46 and 45 kDa, 43 kDa pseudocathepsin D, 39 kDa mature single and two chained cathepsin D: 31 kDa (heavy chain) and 14 kDa light chain of cathepsin D. Unlike cow’s milk, in ewe’s milk was not determined the presence of cathepsin D, proteolytic enzyme which could affect on the production of dairy products especially cheese, which are traditionally produced in Croatia and Mediterranean. The aim of the present study was to determine presence of enzyme cathepsin D in ewe milk and its forms. Samples of ewe’s milk were collected at a family farm in central Dalmatia with autochthonous Croatian breed, Dalmatian Pramenka. Cathepsin D and its forms were detected in ewe’s milk using a modified protocol of Western Blotting method due to the lack of appropriate antibodies. In this research, antibodies that are reared in the goat against a human cathepsin D was used. Addition of substrate 4-Chloro-1-naphthol or DAB solution gave no reaction so those two substrate were mixed and pour over the membrane. The results confirmed the presence of procathepsin D, mature and heavy chain of cathepsin D. Light chain cathepsin D was not detected.

milk; cathepsin D; ewe milk; Western blotting

nije evidentirano