This volume is devoted to the developments in the branch of polymer chemistry which deals with immobilized systems. These systems are widely used in fields connected with metabolism in humans, animals, plants and micro-organisms. The study of these artificial immobilized systems permits the understanding and design of the function and behaviour of natural substances in living organisms. The book contains the latest achievements in the field of synthesis of polymeric derivatives of different natural substances such as: proteins; peptides; amino acids; poly- and monosaccharides; nucleic acids; nucleosides; nucleotides; coenzymes; vitamines; alkaloids; antibiotics; steroids; hormones; and others. Special attention is given to natural and synthetic carriers and the influence of their chemical structure on the efficiency of systems obtained. This work should be of value and interest to researchers in the field of polymer chemistry, biotechnology and genetic engineering, medical chemistry, bio-organic chemistry and enzymology.