Our lab has previously demonstrated a technique that allows the conjugation of aggregate-free metallic porphyrins and human serum albumin (HSA) in aqueous solutions. We present the fluorescence, absorption, lifetime and circular dichroism of several albumin-porphyrins (zinc, manganese, magnesium, hemin, tin and metal-free) compounds.  Subsequently, numerous irradiations with a 405nm laser were performed and the same metrics were utilized to assess, what, if any structural changes occurred in HSA. In most of the compounds (apart from hemin and manganese) a severe decrease in fluorescence was observed accompanied with an increased bleaching of the porphyrin. Regarding structural changes, we observed a decrease in alpha helix which paralleled an increase in distorted alpha helix as measured by CONTINLL. These structural changes appear to be reflected by an increase in the fluorescence lifetime of these compounds.<br/>For our computational studies, all the porphyrins were geometry optimized using DFT with ORCA 4.2 until they reached the standard convergence criterion. Blind docking for all the porphyrins was conducted in Autodock 4.26, with several binding clusters recognized (Cys-34, Tyr-138, His-67) that where in similar energy ranges. Molecular dynamic simulations were utilized to explore these interactions in NAMD.

Porphyrin mediated structural changes of human serum albumin, experimental and computational modeling

ACS Spring Meeting 2021

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