313 corresponding to u s pat no 4 226 878 2 japanese patent application kokai sho 57 131769 corresponding to u s pat no 4 607 046 and 3 wo 98 27053 valproic acid derivatives include for example the compounds disclosed in japanese patent application kokai hei 7 316092 corresponding to ep 0632008a1 the polymer of the present invention may be prepared by the method described hereinafter in examples known methods or the method of the following reactions 1 u02dc 3 is reacted with hydrazine shown by the formula nh 2 u2014 nh 2 in an organic solvent such as dimethylformadmide dmf etc or without solvent at room temperature 10 u02dc 25 u00b0 c to prepare the polymer of the formula ii wherein d 1 x 1 and y 1 are mol degree of polymerization of l glutamic acid connecting coor 1 wherein r 1 is c1 u02dc 6 alkyl or benzyl l glutamic acid connecting cooh and l glutamic acid connecting nh 2 respectively with the proviso that 1 sum of d 1 x 1 and y 1 equals to d 2 d 1 may be 0 3 each l glutamic acid connecting coor 1 wherein r 1 is defined as hereinbefore cooh and nh 2 may be bonded at random in order see the method described in j appl biochem 2 25 1980 in the reaction 2 for example saccharide g may be conjugated to hydrazine in the polymer of the formula ii described hereinafter and 2 imino 2 methoxyethyl 1 thiosaccharide in a weak alkaline condition e g in borate buffer solution ph9 u02dc 10 or b by reacting the polymer.