re various advantages associated with performing reactions in a homogenous phase (2:264-265). Polypeptide chains are generally attached to some soluble polymer. During processing, peptidyl polymer is precipitated and washed. Crystallization-precipitation of the intermediate can usually be effected through the addition of ether (2:264-265). The purified material may then be redissolved, deblocked, and combined with another appropriately blocked and activated amino acid (3:169-170).
Shemyakin et al. (1965) initially employed high molecular weight polystyrene for LPPS. Because of the absence of crosslinking, this compound remains soluble in some organic solvents. In recent years, however, the most commonly used LPPS polymer has been polyethyleneglycol (HO-CH2-CH2-(O-CH2-CH2-)nO-CH2-CH2-OH). First introduced by Mutter and Bayer (1972), the molecular weight of polyethyleneglycol may range from 2,000 to 20,000 dalton. Anchoring amino acids are usually attached to the polymer at their C-terminals. This connection may involve eith
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