Nwankwoala R P, Pento J T
Horm Res. 1981;15(3):198-206. doi: 10.1159/000179454.
The cytosolic fraction of porcine thyroid, liver, kidney and brain tissue contains proteolytic activity capable of calcitonin degradation into peptide fragments. The degree and pattern of calcitonin fragmentation produced by the tissue examined in this study were determined by subjecting aliquots of incubation media to gel filtration chromatography immediately after incubation. Thyroid cytosol produced calcitonin fragmentation in a time-dependent manner. Fragmentation produced by liver, kidney and brain appeared to be quantitatively and qualitatively different from that produced by the thyroid. Hormone degradation produced by thyroid cytosol was substantially inhibited by p-hydroxymercuribenzoate, thimerosal and iodoacetamide but not by pepstatin. The thyroid cytosolic peptidase may be involved in calcitonin turnover and presecretory regulation within the "C' cell. Further, fragmentation within the thyroid may be responsible for the multiple immunoreactive forms of calcitonin which have been detected in the circulation.
猪甲状腺、肝脏、肾脏和脑组织的胞质部分含有蛋白水解活性，能够将降钙素降解为肽片段。在本研究中，通过在孵育后立即对等分的孵育培养基进行凝胶过滤色谱分析，确定所检测组织产生的降钙素片段化程度和模式。甲状腺胞质溶胶以时间依赖性方式产生降钙素片段化。肝脏、肾脏和脑产生的片段化在数量和质量上似乎与甲状腺产生的不同。对羟基汞苯甲酸、硫柳汞和碘乙酰胺可显著抑制甲状腺胞质溶胶产生的激素降解，但胃蛋白酶抑制剂则无此作用。甲状腺胞质肽酶可能参与“C”细胞内降钙素的周转和分泌前调节。此外，甲状腺内的片段化可能是循环中检测到的多种降钙素免疫反应形式的原因。
