Before revision:  Hence, we propose and examine the ` slowest-first' scheme, whereby protein sequences evolved structural asymmetry to accelerate co-translational folding (CTF): the slowest-folding elements (e.g. \beta-sheets) are positioned near the N terminal so they have more time to fold during translation.
After revision:  Hence, we propose and examine the ` slowest-first' scheme, whereby protein sequences evolved structural asymmetry to accelerate CTF: the slowest of the cooperatively-folding segments are positioned near the N terminal so they have more time to fold during translation.