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

Abstract 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-C3N4 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.