6.4.1.4	comparison of structures, beta subunit hexamers of 3-methylcrotonyl-CoA carboxylase and geranyl-CoA carboxylase, EC 6.4.1.5. Structural differences in the active site region of both enzymes explain their distinct substrate preferences and support two distinct lineages of biotin-dependent acyl-CoA carboxylases, one carboxylating the alpha carbon of a saturated organic acid and the other carboxylating the gamma carbon of an alpha-beta unsaturated acid. A glycine residue in geranyl-CoA carboxylase is replaced by phenylalanine in 3-methylcrotonyl-CoA carboxylase, which blocks access by the larger geranyl-CoA substrate	
6.4.1.4	crystal structures diffracted to 1.5 A resolution of the Pseudomonas aeruginosa MCC (PaMCC) holoenzyme are shown, alone and in complex with coenzyme A. The structures show that the architecture and overall shape of PaMCC are strikingly different when compared to propionyl-CoA carboxylase	
6.4.1.4	crystal structures of the Pseudomonas aeruginosa MCC (PaMCC) holoenzyme, alone and in complex with coenzyme A are shown at 2.9 and 3.5 A resolution respectively. The structures show that the architecture and overall shape of PaMCC are strikingly different when compared to propionyl-CoA carboxylase