Life is traditionally seen as being driven by energy from the sun, however deep sea organisms have no access to sunlight, so they depend on nutrients found in the dusty chemical deposits and hydrothermal fluids around the hydrothermal vent zones, where they live. In this study, we use neutron spin-echo spectroscopy (NSE) to measure the inter-domain motions of the inorganic pyrophosphatase (IPPase) enzyme derived from thermostable microorganisms. IPPase is of extreme interest for biophysical studies because of their inherent chemical and thermal stability and high temperature activity. It has a hexameric quaternary structure with a molecular mass of approximately 120kDa (each subunit is about 20kDa molecular weight), which is a large oligomeric molecular structure. Study of the slow inter-domain motions that occur in the protein is the key to understand why IPPase can perform catalytic activity at much higher temperature than normal enzymes, thus can adapt to the extreme environment present at the seabed [1-3]. NSE spectroscopy is able to probe these slow inter-domain motions directly in the time-domain, as has already been established in other studies[4,5]. The length and timescale of NSE are right in the ranges from sub-Angstrom and picoseconds to nanometers and several tens of nanoseconds and beyond. Distinguishable dynamical behavior found between two proteins reveals local flexibility and conformational substates unique to oligomeric structures. Our results greatly help understanding the relation between protein dynamics and their biological functions. [1] X.-Q. Chu, et. al, JPCB 116, 9917 (2012). [2] X.-Q. Chu, et. al, Soft Matter 6, 2623(2010). [3] X.-Q. Chu, et. al, JPCL 4, 936 (2013). [4] R. Biehl, et. al, Soft Matter 7, 1299 (2011). [5] N. Smolin, et. al, Biophys. J. 102, 1108 (2012).