A polymer structure of Formula (Ia) useful for conjugating with a protein-based recognition molecule (PBRM) having a molecular weight of 40 kDa or greater: ** Formula ** wherein: the structure comprises poly (1-hydroxymethylethylene hydroxymethyl -formal) (PHF) having a molecular weight ranging from 2 kDa to 40 kDa； each occurrence of D is independently a therapeutic agent having a molecular weight of <；= 5 kDa； LD1 is a fraction containing carbonyl； wherein ** Formula ** in ** Formula ** contains a biodegradable bond so that when the bond is broken, D is released in an active form for the intended therapeutic effect； and the ** Formula ** in ** Formula ** between LD1 and D denotes the direct or indirect binding of D to LD1； ** Formula ** where ** Formula ** is different from ** Formula ** in * * Formula ** and LP2 is a fraction that contains a functional group that is capable of forming a covalent bond with a functional group of the PBRM, and the group ** Formula ** between LD1 and LP2 denotes the direct or indirect binding of LP2 to LD1； m is an integer from 1 to 300, m1 is an integer from 1 to 140, m2 is an integer from 1 to 40, m3 is an integer from 1 to 18, and the sum of m, m1, m2 and m3 ranges from 15 to 300Una estructura polimérica de Fórmula (Ia) útil para conjugar con una molécula de reconocimiento basada en proteínas (PBRM) que tiene un peso molecular de 40 kDa o mayor:**Fórmula** en donde: la estructura comprende poli(1-hidroximetiletilen hidroximetil-formal) (PHF) que tiene un peso molecular que varía de 2 kDa a 40 kDa； cada aparición de D es independientemente un agente terapéutico que tiene un peso molecular de <；=5 kDa； LD1 es una fracción que contiene carbonilo； en donde **Fórmula** en **Fórmula** contiene un enlace biodegradable de manera que cuando el enlace se rompe, D se libera en una forma activa para el efecto terapéutico pretendido； y el**Fórmula** en **Fórmula** entre LD1 y D denota la unión directa o indirecta de D a LD1；**Fórmula** en
