The energy surface of apomyoglobin appears to have a sizable energy trap that very early condenses the protein into a topology with a very small cooperative unit (the AGH core), found in the totally folded protein, which remains during the rest of the folding process, perhaps serving as a template. It seems likely that the presence of secondary structure is required before the 'nucleation' of this tertiary structure can take place, and the required helical structure has, indeed, already formed. The helical structure can be viewed as a 'framework' for the formation of the small cooperative unit. The next stage is further growth of ordered structure on top of the small AGH core in both the amount of residues in helices and an extension of tertiary contacts spreading out from the small core area. Perhaps surprisingly for a small protein like apomyoglobin, a second kinetic phase whereby other residues condense into a native fold occurs much later, on relatively slow time scales. Hence, two folding units describe the folding of this protein. From this degree of detail, it is fairly easy to see how the early structures, even if local and fluctuating in nature, result in the required constriction in conformational space that accelerates and directs the folding process.