That vitamin B molecule is biotin. Now, the energy source that this enzyme uses is ATP. So it basically hydrolyzes that ATP to form ATP, and it uses the energy that is released to drive this reaction forward. Now, the carbon source that it uses is bicarbonate. It uses a bicarbonate to basically take that carbon dioxide and place it onto the proponel coenzyme A. And that helps us generate the methylmelanyl coenzyme A.