Biochemical coupling between two enzymatic reactions - Enzymes physically associated?
The enzymes don't need physical interactions to couple reactions. Some enzymes do share subunits which are physically associated, but this is a special case. The following review gives a sort of general example during glycolysis, 


  For example, in the biochemical pathway that breaks down glucose for energy, two enzymes work one after the other to create a high-energy ATP molecule:


We can also look at the peptidyltransferase reaction during the elongation step in translation. Earlier, an aminoacyl tRNA synthetase catalyzed the covalent addition of an amino acid to it's associated tRNA. The energy from breaking this bond in the ribosome provides energy for the peptidyltransferase to link the two amino acids together. This isn't assuming the ATP/GTP needed by elongation factors, etc.