Trapping gases by high pressure

It is possible to trap gaseous reactants in the active site of an enzyme by pressurizing a crystal of the enzyme with the gas and cryocooling. If interested in trying this for your protein, please contact Marian Szebenyi or Qingqiu Huang.
Trapping gases by high pressure, feature image

Lower-pressure cryocooling system: pressure usually used is 5-20 MPa, for gas trapping:
a) Gas-loading and Cryo-cooling apparatus  and b) Schematic overall view.

HPT: gas trapping apparatus
a)
gas trapping sketch
b)

 

A pressure cryo-cooling system is built to safely handle biological gases, such as carbon dioxide and oxygen, including hazardous gases such as nitric oxide.

An example: Carbonic anhydrase (CA) regulates the pH of the blood by converting carbon dioxide to bicarbonate. There was a model for how the enzyme does this, but pressurizing human CA II with CO2, at a pressure of 15 atmospheres, and cryocooling, let researchers actually see where the CO2 goes and confirm the model (1). Later work allowed comparison of CO2 binding in bacterial and human CAs (2).

CO2 in the active sites
CO2 in the active sites of (left) human hCA II, and (right) P. aeruginosa psCA3

 

References:

(1) Domsic et al. 2008, J. Biol. Chem. 45, 30766-30771
(2) Aggarwal et al. 2015, Biochemistry 54, 6631-6638