The Effect of Calcium Concentration and pH Levels on the Proteolysis of the Two-Domain Neural-Cadherin Construct

Neural Cadherin (NCAD) Is a classical cadherin that plays a critical role In synaptogenesis and regulation of synaptic plasticity. One of Its characteristics as a classical cadherin Is Its calcium-dependent resistance to proteolytic cleavage. However, Candida albicans, the most common fungal pathogen of humans, has a virulence mechanism In which host tissue Is Invaded by degrading cadherin with secreted aspartyl proteases (SAPs). To Investigate the conditions In which this Invasive species proteolyzes cadherin, we used a-chymotrypsin as a model protease and the first two domains of Neural Cadherin (NCAD12). We performed time-dependent, Ca^^- dependent, and pH-dependent proteolysis of NCAD12 to establish calcium\u27s protective characteristics and explore the effect of pH on proteolytic cleavage. The achymotrypsln substrate, BTEE, was used to evaluate the activity of the protease. Ca concentrations near biological levels were shown to protect NCAD12 from cleavage by a-chymotrypsIn. However, the protease was shown to be an Ineffective SAP simulator because of low activity near and below pH 6. These studies established protocols for assessing the susceptibility of NCAD12 to cleavage by proteases calcium concentration, and pH. The substrate, BTEE, the activity of a model protease, a-chymotrypsIn, as a function of pH