The Surface Plasmon Resonance Imaging (SPRI) sensor for papain determination based on the interaction between the immobilized cystatin and aqueous papain solution has been developed. The development of the sensor is a stage in the development of the sensor for the determination of cystein proteinases of the papain group. Cystatin was immobilized onto a gold chip by means of a thiol underlayer (cysteamine) and EDS/NHS reaction. Conditions of cystatin- papain interaction were optimized (pH, time of interaction and cystatin concentration). The developed sensor works within the range of 1 - 10 ng ml-1. However, the precision of measurements (RSD equal to 45%) should be improved. The response of the sensor to papain is specific. This was checked using BSA as a reference.
Protein & Peptide Letters publishes short papers in all important aspects of protein and peptide research, including structural studies, recombinant expression, function, synthesis, enzymology, immunology, molecular modeling, drug design etc. Manuscripts must have a significant element of novelty, timeliness and urgency that merit rapid publication. Reports of crystallisation, and preliminary structure determinations of biologically important proteins are acceptable. Purely theoretical papers are also acceptable provided they provide new insight into the principles of protein/peptide structure and function.