Abstract: Compounds of formula (I): ##STR1## wherein: R.sup.1 is hydrogen, alkyl, aralkyl, --COR.sup.a, --COR.sup.b, --CSR.sup.a, --CSR.sup.b, --SO.sub.2 R.sup.b, --CONHR.sup.b, --CSNHR.sup.b, --CONR.sup.b R.sup.b or --CSNR.sup.b R.sup.b ; R.sup.2 is hydrogen or alkyl; R.sup.3 is hydrogen, alkylidene, substituted alkyl, or R.sup.b ; R.sup.4 is optionally substituted alkyl, cycloalkyl, or aryl; R.sup.5 is R.sup.b O--, R.sup.b R.sup.b N--, R.sup.b HN--, aralkyloxycarbonyloxy or aralkyloxycarbonylamino, or R.sup.5 is --(CH.sub.2).sub.p --D--(CH.sub.2).sub.r --, where D is a single bond, carbonyl, oxygen, sulfur, --NH--, --(CH.sub.2 .dbd.CH.sub.2)-- or --NHCO--; and p and r are each 0 or an integer from 1 to 5; A is --(CH.sub.2).sub.m --B--(CH.sub.2).sub.n -- where B is a single bond, carbonyl, oxygen, sulfur, --NH--, --(CH.sub.2 .dbd.CH.sub.2)-- or --NHCO--; and m and n are each 0 or an integer from 1 to 5; R.sup.a is alkoxy, aralkyloxy, aryloxy or alkoxycarbonyl; R.sup.

Abstract: There are disclosed a DNA-immobilized microsphere comprising DNA chains having base sequences which bind a specific protein specifically, and a carrier having a particle size of not more than 50 .mu.m and not less than 0.01 .mu.m which does not adsorb any protein, said carrier and said DNA chains being bound to each other by a chemical bond, and a process for purifying a protein using said microsphere.