Caseins are readily available and can be efficiently extracted from milk in high purity and amount, hence, often explored as a potential emulsifying, coagulating, and stabilizing agent in various fields of chemistry. Caseins may also be considered in the preparation of protein-metal nanoparticle conjugates for use in various applications. However, the casein proteins contain few to none of the free thiols that are essential in the reduction of metal ions and in the stability of the conjugates. In this study, thiolated caseins were prepared with 2-iminothiolane reagent, more commonly known as Traut’s reagent. The modified caseins were characterized to determine the degree of thiolation. The Ellman assay showed that approximately four moles of thiols were introduced per mole of casein. Moreover, SDS-PAGE showed a slight increase in molecular weight which may indicate a possible increase in disulfide bridging of the casein polypeptides. Further analyses by FTIR and mass spectrometry are needed to fully confirm the thiolation. The use of the thiolated caseins in the preparation of protein-metal nanoconjugates and their use as biosensors will be studied in the near future.

Preparation and preliminary characterization of thiolated Caseins for use in the synthesis of protein-stabilized metal nanoparticles.

ACS Spring Meeting 2021

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