3D Structure of Liver Alcohol Dehydrogenase
On this page, you can see a liver alcohol dehydrogenase enzyme complexed with NAD+ and substituted benzyl alcohols.
Reset and spin the Liver Alcohol Dehydrogenase model
Notice the two identical subunits of LADH colored in green and blue. The model shows the secondary structure, containing both alpha helices and beta sheets. The benzyl alcohol substituents are shown in CPK color.
Here you can see the active site zinc atom (in red) on one of the subunits. Because this zinc atom is in the active site, it is coordinated to the substrate, a benzyl alcohol substiuent which is shown in thick wireframe CPK color. The model also shows how the zinc atom is complexed with Cys-46 (in green), Cys-174 (in magenta), and His-67 (in deep sky blue), allowing for stability of the Zinc atom, as well as access to the benzyl alcohol. The NAD+ cofactor that LADH requires to be active is shown in blue, adjacent to the active zinc site. The other subunit contains these exact structures as well.
Here we see four protein ligands that completely surround the inactive zinc atom, causing it to be inaccessible to alcohols. These ligands are Cys-97 (in purple), Cys-100 (in deep pink), Cys-103 (in medium spring green), and Cys 111 (in light salmon).It is thought that this zinc plays a role in maintaining the stability of the protein. The other subunit contains an inactive zinc as well.
Nathan Silva and David Marcey: An Introduction to Jmol Scripture
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