METHOD OF EVALUATION OF SELECTIVE CHANGES IN COMPARTMENTALIZATION OF ACTIVITY OF LYSOSOMAL CYSTEINE PROTEINASES

Aim. To develop a quantitative method for evaluation of selective changes in compartmentalization of the activity of lysosomal cysteine proteinases. Materials and methods. Activity of cathepsins B, L and H was defined separately in the cytoplasmic and lysosomal fractions of tissue homogenates of Wistar line rats by spectrofluorometrical registration of the amount of a cleavage product of a specific substrate of 7amido-4-methylcoumarin. The activity of acid phosphatase was determined using the commercial kit «Vital Diagnostics SPb» (Russia, St. Petersburg). Results. A method for evaluation of selective changes in compartmentalization of lysosomal cysteine proteases activity is proposed; that is based on a quantitative comparison of the shares of extra-lysosomal activity of the respective cathepsin and acid phosphatase. Conclusion. A method for evaluation of a selective change in the compartmentalization of the activity of lysosomal cysteine proteinases is proposed based on the quantitative comparison of shares of extra lysosomal activity of a respective cathepsin and of acid phosphatase. The results are presented as a non-dimensional coefficient of selective compartmentalization of the activity (КSCА) which may take three ranges of values. Since in case of a uniform release of acid phosphatase and a studied cathepsin the ratio of the share of extra lysosomal activity is close to 1, it is reasonable to interpret the deviation of the obtained values from 1 as positive or negative. It is proposed to interpret КSCА approaching 1as a damage to the lysosomal membrane (labilization), with evaluation of the extent of damage by the extent of rise of the shares of extra lysosomal activity. Positive values of КSCА indicate permeabilization of lysosomal membrane with a selective release of a certain cathepsin into the extra lysosomal space. Negative values of КSCА at the given stage of understanding of lysosomal cysteine proteinases can be interpreted as the result of impact of factors that selectively inhibit activity of a studied cathepsin in the extra lysosomal fraction.