Browsing by Author "Singh, Surjeet"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Single-molecule analysis of osmolyte-mediated nanomechanical unfolding behavior of a protein domain
    (Elsevier B.V., 2023-09-16T00:00:00) Bajaj, Manish; Muddassir, Mohd; Choi, Bumjoon; Singh, Priyanka; Park, Jong Bum; Singh, Surjeet; Yadav, Manisha; Kumar, Rajesh; Eom, Kilho; Sharma, Deepak
    The small organic molecules, known as osmolytes being ubiquitously present in different cell types, affect protein folding, stability and aggregation. However, it is unknown how the osmolytes affect the nanomechanical unfolding behavior of protein domain. Here, we show the osmolyte-dependent mechanical unfolding properties of protein titin immunoglobulin-27 (I27) domain using an atomic force microscopy (AFM)-based single-molecule force spectroscopy. We found that amines and methylamines improved the mechanical stability of I27 domain, whereas polyols had no effect. Interestingly, glycine betaine (GB) or trimethylamine-N-oxide (TMAO) increased the average unfolding force of the protein domain. The kinetic parameters analyzed at single-molecule level reveal that stabilizing effect of osmolytes is due to a decrease in the unfolding rate constant of I27, which was confirmed by molecular dynamics simulations. Our study reveals different effects that diverse osmolytes have on the mechanical properties of the protein, and suggests the potential use of osmolytes in modulating the mechanical stability of proteins required for various nano-biotechnological applications. � 2023 Elsevier B.V.
  • Thumbnail Image
    Item
    Single-molecule force-unfolding of titin I27 reveals a correlation between the size of the surrounding anions and its mechanical stability
    (Royal Societty of chemistry, 2018) Muddassir, Mohd; Manna, Bharat; Singh, Priyanka; Singh, Surjeet; Kumar,Rajesh; Ghosh, Amit; Sharma, Deepak
    Each cellular protein is surrounded by a biochemical milieu that affects its stability and the associated function. The role of this surrounding milieu in the proteins’ mechanical stability remains largely unexplored. Herein, we report an as yet unknown correlation between the size of the surrounding anions and the mechanical stability of a protein. Using single-molecule force spectroscopy of the 27th domain (I27) of human cardiac muscle protein titin, we show that the average unfolding force of the protein decreases with increase in the ionic radii of the surrounding anions in the order Cl− > Br− > NO3− > I− > SO42− ≈ ClO4−, indicating an inverse correlation between anion size and the mechanical stability of I27. The destabilizing effect was attributed to the combined effect of increase in the unfolding rate constant and unfolding distance upon incubation with the anion. These findings reveal that anion size can significantly affect the mechanical resistance of proteins and thus could be a convenient and promising tool for regulating the mechanical stability of proteins.