These answers are actually quite wrong. 1) Proteins are soluble and most stable when folded (laws of thermodynamics, entropy gains by folding), nobody wants to purify unfolded, catalytically inactive protein. 2) DTT does not cause unfolding. Does not. Proteins are often found in highly reducing environments, so DTT stops oxidation of the protein (especially helpful in metal containing proteins) and the formation of unwanted disulfide bonds. If your protein requires disulfide bonds then you may not want to use DTT.
A cigarette has two flavors, regular and menthol while pipe tobacco has many flavors, ranging from spicy to fruity to sweet. 3. The flavor and aroma of cigarettes are added chemically while the flavor and aroma of pipe tobacco are added while the plant is still growing by spraying them on the leaves.
The big difference is in quality. Cigarettes are adulterated with tons of chemicals and waste tobacco that has been reprocessed, rolled into sheets, sprayed with tobacco juice and god know what else then cut up and mixed in with everything else. Cigarettes are full of poisons and artificial garbage that isn't present in quality pipe tobacco. Some OTC pipe tobaccos use propylene glycol and some preservatives but are no where near being adulterated to the level that cigs are.