NOVELTY - Enzyme-based method for coupling- and/or crosslinking reactions of e.g. textiles, medical products, cosmetic products, comprises coating the surfaces of the products, modifying suitable compounds such as natural monomers to polymers, preferably cellulose-containing or protein-containing natural polymers or fiber materials such as textiles including cotton, wool or silk, or synthetic monomers to polymers or a mixture of natural and synthetic monomers to polymers, and coupling and/or crosslinking suitable compounds as coupling agents to the compounds that are to be modified.    USE - The enzyme-based system (preferably oxirane-generating system) is useful for providing improvement in properties and/or contributing new properties: in textile fiber materials i.e. improving strength properties of textile substances by coupling/crosslinking polysaccharides such as starch, or providing crease resistance-, resilient-, flame-retardant-, absorbance- and superabsorbance-, release- and repellent-, antimicrobial- and insecticide-, environmentally protective-, UV and heat resistant-, air pollution protection-, weather resistant-, shrink-proofing-, abrasion and pilling resistant-, antistatic-, grease proof/barrier-, antiyellowing-, odor removing- and moisture regulating-properties, where the properties are simultaneously or successively introduced, or providing metal or metal ions, fluorescent and luminescent substances for the preparation of security textile and designed textile, where the improvement and/or change in the properties are provided to medical materials such as non-thrombogenic materials, cardiovascular materials, orthopedic materials, other applications such as dental application materials (e.g. filling cement), eye application materials (e.g. synthetic lenses/contact lenses), combustion application materials, auditory application materials, tissue engineering material, sutures, drug delivery system, sensor material or bioelectrode materials; and in further substances such as cosmetic substances, paints, utility textiles such as carpets, wood- or plastic-based structural materials and further materials in which coating (coupling and/or crosslinking) of substances or substances play a role (all claimed).    ADVANTAGE - The method: provides high yields of oxirane-containing fatty acids, fats and oils, without the requirement of increased reaction time and high cost; avoids the unwanted side reactions e.g. reaction with water and competing with necessary substrate such as hydrogen peroxide; prevents the breakage of textile fabrics; and has high performance, no toxicity and low environmental impact.    DETAILED DESCRIPTION - Enzyme-based method for coupling- and/or crosslinking reactions of textiles, medical products, cosmetic products, paints, utility textile products such as carpets, wood- or plastic-based building materials, comprises coating the surfaces of the products, modifying suitable compounds such as natural (i.e. naturally occurring) monomers to polymers, preferably cellulose-containing or protein-containing natural polymers or fiber materials such as textiles including cotton, wool or silk, or synthetic (i.e. synthetically manufactured) monomers to polymers or a mixture of natural and synthetic monomers to polymers or biomaterials for medical products or substances such as cosmetics, paints, utility textile products such as carpets, wood- or plastic-based structural materials and further materials, and coupling and/or crosslinking suitable compounds as coupling agents to the compounds that are to be modified, where the suitable compounds are substances that are similar or different from the above to be modified substances, the coupling and/or crosslinking step is carried out during finishing step in the textile treatment, and the suitable compounds are compounds such as polysaccharide, for improving the surface finishing and/or strength properties, or materials that are used in finishing processes such as brightening, dyeing, introducing corresponding barrier/grease proof substances and antiyellowing substances, or materials that are used for further finishing process, or materials that are used for altering and/or enhancing biomaterials for medical products or cosmetics, paints, utility textile products such as carpets, wood- or plastic-based structural components and further materials, where: the enzyme comprises immobilized lipase or esterase, protease, amidase, transferase, acylase, glycosidase, glycotransferase, oxidoreductase, peroxidase, laccase or other oxidases; the method is carried out in oxirane-generating system and optionally in other coupling and/or crosslinking systems; the method comprises peroxide or per-compounds or peroxide-generating system and special coupling and/or crosslinking compounds (coupling enhancers), which serves as coupling and/or crosslinking agents and are activated by the enzyme; all the above compounds comprise property altering compounds; and the reaction is carried out during the formation of oxiranes in 2-pot, 3-pot or multi-pot systems.