Enzymes are catalysts in biochemical reactions that, by definition, increase rates of reactions without being altered or destroyed. However, when that enzyme is a protease, a subclass of enzymes that hydrolyze other proteins, and that protease is in a multiprotease system, protease-as-substrate dynamics must be included, challenging assumptions of enzyme inertness, shifting kinetic predictions of that system. Protease-on-protease inactivating hydrolysis can alter predicted protease concentrations used to determine pharmaceutical dosing strategies. Cysteine cathepsins are proteases capable of cathepsin cannibalism, where one cathepsin hydrolyzes another with substrate present, and misunderstanding of these dynamics may cause miscalculations of multiple proteases working in one proteolytic network of interactions occurring in a defined compartment. Once rates for individual protease-on-protease binding and catalysis are determined, proteolytic network dynamics can be explored using computational models of cooperative/competitive degradation by multiple proteases in one system, while simultaneously incorporating substrate cleavage. During parameter optimization, it was revealed that additional distraction reactions, where inactivated proteases become competitive inhibitors to remaining, active proteases, occurred, introducing another network reaction node. Taken together, improved predictions of substrate degradation in a multiple protease network were achieved after including reaction terms of autodigestion, inactivation, cannibalism, and distraction, altering kinetic considerations from other enzymatic systems, since enzyme can be lost to proteolytic degradation. We compiled and encoded these dynamics into an online platform (https://plattlab.shinyapps.io/catKLS/) for individual users to test hypotheses of specific perturbations to multiple cathepsins, substrates, and inhibitors, and predict shifts in proteolytic network reactions and system dynamics.

中文翻译：

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重新评估酶动力学：考虑蛋白水解网络中蛋白酶作为底物的相互作用。

酶是生化反应中的催化剂，根据定义，酶可提高反应速率而不会被改变或破坏。但是，当该酶是一种蛋白酶（一种水解其他蛋白质的酶的子类）并且该蛋白酶处于多蛋白酶系统中时，必须包括蛋白酶作为底物的动力学，这对酶的惰性提出了挑战，改变了该系统的动力学预测。蛋白酶对蛋白酶的失活水解可以改变用于确定药物剂量策略的预测蛋白酶浓度。半胱氨酸组织蛋白酶是一种能够使组织蛋白酶相食的蛋白酶，其中一种组织蛋白酶会水解另一种存在底物的组织，而对这些动力学的误解可能会导致多种蛋白酶的误算，这些蛋白酶在一个确定的区域内发生的相互作用的一个蛋白水解网络中起作用。一旦确定了单个蛋白酶与蛋白酶结合和催化的速率，就可以在一个系统中使用多种蛋白酶协同/竞争性降解的计算模型来探索蛋白水解网络动力学，同时结合底物裂解。在参数优化过程中，发现发生了其他分散反应，其中灭活的蛋白酶变成了对剩余活性蛋白酶的竞争性抑制剂，从而引入了另一个网络反应节点。综上所述，在包括自动消化，失活，食人和分散注意力等反应条件之后，就可以改善多种蛋白酶网络中底物降解的预测，改变了其他酶体系的动力学考虑，因为酶可能会因蛋白水解降解而丢失。