No abstract

In recent years, enzymes have risen as promising therapeutic tools for different pathologies, from metabolic deficiencies, such as fibrosis conditions, ocular pathologies or joint problems, to cancer or cardiovascular diseases. Treatments based on the catalytic activity of enzymes are able to convert a wide range of target molecules to restore the correct physiological metabolism. These treatments present several advantages compared to established therapeutic approaches thanks to their affinity and specificity properties. However, enzymes present some challenges, such as short in vivo half-life, lack of targeted action and, in particular, patient immune system reaction against the enzyme. For this reason, it is important to monitor serum immune response during treatment. This can be achieved by conventional techniques (ELISA) but also by new promising tools such as microarrays. These assays have gained popularity due to their high-throughput analysis capacity, their simplicity, and their potential to monitor the immune response of patients during enzyme therapies. In this growing field, research is still ongoing to solve current health problems such as COVID-19. Currently, promising therapeutic alternatives using the angiotensin-converting enzyme 2 (ACE2) are being studied to treat COVID-19.

Lactobacillus helveticus ATCC 15009 (wildtype) membrane preparations hydrolyzed Mg 2+ -ATP as a function of K + concentration (2-200 mM). Mg 2+ -ATP hydrolysis by L. helveticus membranes was strongly inhibited in the absence of exogenous K + , while it amounted to 6 nmol ATP hydrolyzed min -1 (mg membrane protein) -1 at 50 mM KCl (saturating conditions) and pH 7.2. The K + -dependent ATPase of L. helveticus displayed a relatively high affinity for potassium ions (K m = 800 µM) and was not affected by pretreatment of membranes with N,N'-dicyclohexylcarbodiimide. Membrane preparations were subjected to hypotonic shock to obtain a maximum yield of open profiles. The formation of a maximum level of enzyme-phosphate complex with a molecular mass of approximately 82 kDa was induced upon treatment of L. helveticus membrane preparations with low concentrations of [γ-32 P]ATP in the presence of K + and La 3+ ions and was visualized by acidic SDS-PAGE. It was concluded that L. helveticus membranes contain an inwardly directed K + pump whose presence is discussed in terms of its putative role in cytoplasmic pH regulation.