Suitable reagents for linker construction include one or more compounds consisting of activated forms of amino-protected alkyl or aryl amino acids such as compounds of the formula R???NH???(CH2)n???CO2R??? or R???NH???(CH2)nX(CH2)m???CO2R???, where R is an acid- or base-labile protecting group, R??? is a reactive ester or anhydride group, X is aryl, O, S, or NH, and where n and m are 0-12.