Excellency of pyrimidinyl moieties containing α-aminophosphonates over benzthiazolyl moieties for thermal and structural stability of stem bromelain.

An efficient approach has been made for the synthesis of a series of novel di α-aminophosphonates by the reaction of terephthalaldehyde with various pyrimidine/benzthiazole amines and diethyl phosphite using sulfonated graphitic carbon nitride - SA@g-CN as catalyst under room temperature and solvent free conditions. Later, the different effects of these newly synthesized α-aminophosphonates as a function of concentration gradient has been scrutinized on the thermal and structural stability of stem bromelain (SBM) through combining the results of various spectroscopic techniques like UV-vis, steady state fluorescence and circular dichroism (CD). Lastly the competitive and distinctive behaviour of α-aminophosphonates towards the stability of SBM has been envisaged using molecular docking simulations which suggest that nature of α-aminophosphonates plays a crucial role for their interactions with SBM. Molecular docking results clearly show that α-aminophosphonates with pyrimidine ring are having more number of hydrogen bonding interaction with amino acid residues of SBM than α-aminophosphonates with benzthiazolyl ring. Sequentially for thermal and structure stability of SBM, concentration of α-aminophosphonates plays an inexorable role and through these results it must be concluded that most of the α-aminophosphonates are stabilizing the SBM upto the 0. 1 mM concentration.