Protein interactions in enzymatic processes in textiles
Keywords: auxiliaries, dyes, protein interactions, surfactants, textile processing.
Enzymes are the catalysts of all reactions in living systems. These reactions are catalysed in the active sites of globular proteins. The proteins are composed by amino acids with a variety of side chains ranging from non-polar aliphatic and aromatic to acidic, basic and neutral polar. This fact allows to a globular 3D protein to create in the active site all ranges of microenvironments for catalysis. Major advances in microbial technology and genetics allow recently the broad range of enzymatic applications in the industry. Enzymatic processes have been increasingly incorporated in textiles over the last years. Cotton, wool, flax or starches are natural materials used in textiles that can be processed with enzymes. Enzymes have been used for desizing, scouring, polishing, washing, degumming, peroxide degradation in bleaching baths as well as for decolourisation of dyehouse wastewaters, bleaching of released dyestuff and inhibiting dye transfer. Furthermore many new applications are under development such as natural and synthetic fibres modification, enzymatic dyeing, finishing etc. Most of the textile processes are heterogeneous where an auxiliary as a dye, enzyme, softener or oxidant have to be taken from the solution to the fibre. These processes require the presence of surface-active agents, ionic force "balancers", buffers, stabilisers and others, and are characterized with high turbulence and mechanical agitation in the textile baths. In this paper it is intended to understand and discuss the major protein interactions within textile processes and to try to anticipate troubleshooting possibilities when enzymes are used. It can be expected that an enzyme protein can interact with all chemical agents in solution due to the large variety of side chains of the outer-amino-acids in the large 3D structure of the protein. Without the aim of being exhaustive various points will be discussed where protein interactions are important for textile processing.