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Unfolding the Mysteries of vWF

Experimental vs. Computational Studies of vWF A2 Domain

Prathysha Kothare

Grade 9

Parkland High School

School Address:   2700 N Cedar Crest Blvd

                                                   Allentown, PA 18104

STUDENT VIDEO
EXPERIENCE
vWF Introduction Video
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Hi! I'm Prathysha Kothare, a freshman at Parkland High School in Pennsylvania. Check out my video to learn a little about me and about how my research fits into the BIGGER picture!

PROJECT ABSTRACT
Abstract
Experimental vs. Computational Studies of vWF A2 Domain

von Willebrand Disease (vWD) debilitates over 4 million people in

the US with most subtypes induced by genetic mutations of the von

Willebrand Factor (vWF), a multimeric glycoprotein responsible for

hemostasis. In normal conditions, vWF’s mechanosensitive A2 domain

unfolds upon blood vessel rupture and initiates clotting. A2 also triggers

enzyme ADAMTS13 to cleave vWF multimers. The studied 1541 A2

mutation induces severe bleeding via unknown mechanisms. The research

question was whether in vitro experimentation via optical tweezers (OT)

and molecular simulation could quantify the unfolding forces for the

wildtype and mutant. The hypotheses stated that, if 1541 mutation was

expressed, then A2 would unfold prematurely or under lower forces. In

addition, if a Calcium ion was expressed, it would effectively stabilize A2

and increase the unfolding force. OT involved pulling the mutant and wildtype using lasers traps to determine domain unfolding force and maximum extension. Secondly, CHARMM, NAMD, VMD, and SOL software platforms were used for molecular modeling of A2 induced to simulated shear flow. Further simulations were conducted to quantify the theoretical stabilization impact of Calcium in A2. Key simulation conclusions were that the average force to stretch the Calcium and 1541 variants were 237% and 66%, respectively, when compared to the wildtype. In addition, OT evidenced 1541's premature or double unfolding, resulting in a contour length 78% that of the wildtype. Thus, both experimentation and simulation explain the mechanisms by which 1541 intensifies protein cleavage and bleeding, and validated Ca2+ ion's successful reinforcement of A2, which gives itt encouraging applications in preventing vWF hemophilia.

SLIDE PRESENTATION
SLIDES

Check out slide 9 for a reala-time molecular dynamic simulation animation of A2 with glycans induced to pulling forces at 50 ang/ns!

Download PDF for simulation procedure

INTERACTIVE DISPLAY BOARD
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EXPERTISE
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