| Background: Ocriplasmin has been developed for the induction
of posterior vitreous detachment in patients with vitreomacular
adhesion. At physiological pH, ocriplasmin is susceptible
to autolytic and proteolytic degradation, limiting its activity
duration. These undesirable properties of ocriplasmin can be
reduced by site-directed mutagenesis, so that its enzymatic
activities can be augmented. This study aimed to design
ocriplasmin variants with improved biological/physicochemical
characteristics via bioinformatics tools.
Methods: This study was performed in Tabriz University of
Medical Sciences, Tabriz, Iran, 2019. Through site-directed
mutagenesis, three ocriplasmin variants were designed. Structural
analysis was performed on the wild-type variant and the mutant
variants using the Protein Interactions Calculator (PIC) server.
The interactions between the S-2403 substrate and the ocriplasmin
variants were studied by molecular docking simulations, and
binding capability was evaluated by the calculation of free
binding energy. The conformational features of protein-substrate
complex systems for all the variants were evaluated using
molecular dynamic simulations at 100 nanoseconds.
Results: The structural analysis of ocriplasmin revealed that the
substitution of threonine for alanine 59 significantly reduced
proteolytic activity, while the substitution of glutamic acid
for lysine 156 influenced autolytic function. The molecular
docking simulation results indicated the appropriate binding
of the substrate to the ocriplasmin variants with high-to-low
affinities. The binding affinity of the wild-type variant for the
substrate was higher than that between the mutant variants and
the substrate. Simulation analyses, consisting of the root-meansquare
deviation, the root-mean-square fluctuation, and the
center-of-mass average distance showed a higher affinity of the
substrate for the wild type than for the mutant variants.
Conclusion: The mutational analysis of ocriplasmin revealed
that A59T and K156E mutagenesis could be used for the
development of a new variant with higher therapeutic efficacy. |