Adsorption of Protein on H-Beta Zeolite Noor Maizura Ismail, Lim Yen Fei, Lim Lai Cheng, Ching Yu Yuen, Khairol Sozana Nor Kamarudin, Hanapi Mat Advanced Process Engineering (APEN) Research Group, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, UTM Skudai, Johor, 81310 Malaysia. Tel: +607-5535590, Fax: +607-5581463, E-mail: HBMat@fkkksa.utm.my Abstract The adsorption of two proteins, cytochrome c and α- chymotrypsin onto H-Beta zeolite was studied. The effect of pH on the adsorption capacity was studied at three different pHs, namely 3, 6, and 9. The adsorption capacity for cytochrome c and α-chymotrypsin was found to be the highest at pH 9 and pH 6 respectively. Increase in pH higher than their pI lead to the decrease in the adsorption capacity for both proteins. This is postulated to be due to electrostatic repulsion between protein and the surface of adsorbent. The adsorption characteristics of different proteins onto H-Beta zeolite depend, apart of experimental conditions used, on protein physical and chemical properties. The adsorption isotherm data of protein is well fitted to the Langmuir model. FTIR analysis was performed for both H-Beta zeolite with and without adsorbed protein to study the interaction between the protein and H-Beta zeolite surface. The observed decrease in the intensities of amide groups in protein structure is most likely a consequence of binding of protein onto H- Beta zeolite. Keywords: Protein, Cytochrome c, α-chymotrypsin, Adsorption, H- Beta Zeolite. Introduction Effective separation and purification of proteins has been an important issue in the biomedical and pharmaceutical industries. A novel protein adsorption has been developed in biotechnology to achieve highly efficient and economical separation processes. In many cases, proteins which have similar physical and chemical properties need to be separated, and thus highly selective adsorbents are desired [1]. Microporous molecular sieves, such as zeolite Y, ZSM-5 and zeolite Beta, have played important roles in acid catalysis because of their peculiar pore structures and strong intrinsic acidities [2]. Zeolite frameworks provide substrates that support the mobilities of the non framework cations that make them good ion exchangers. Due to the presence of never ending intricate pore and channel systems of controlled dimensions and accessibilities, zeolites become excellent sorbents and molecular sieves. Zeolitic material can offer extremely large specific surface area [3]. It has been reported that protein adsorption depends on the pore size of adsorbents, protein size, isoelectric point, hydrophobic interactions and the protein surface chemistry [4-6]. Recent research works are focusing into the development and improvement of mesoporous molecular sieve MCM-41 due to its larger pore volume, which is preferable in separation of larger biological molecule such as protein. However, Ernst et al. [7] reported that the adsorption of amino acids into MCM-41 is much lower than that of microporous adsorbents, H-Beta zeolite and HSZM-11. Research work by Cunman et al. [2] combined the benefits of mesoporous and microporous material to produce a meso-micro porous materials as a bimodal system and gives the benefits of each pore size regime which could potentially improve the efficiency of the zeolite catalysis. This clearly shows that, despite the development in synthesis of the new family of mesoporous molecular sieves, research work is still carried out to investigate and improve the potential of microporous molecular sieves. In this work, the protein adsorption on H-Beta zeolite at various pHs was carried out using cytochrome c and α- chymotrypsin as model proteins. The interaction between protein and H-Beta zeolite surface was studied using Fourier Transform Infrared (FTIR) spectroscopy. Materials and Methods Materials For the adsorption experiments, horse heart cytochrome c and α-chymotrypsin from bovine pancreas purchased from Sigma were used without further purification. H-Beta zeolite used was obtained from Zeolyst International. Aqueous phase were made up in freshly deionised water from Purite Select AN HP40 (Purite Ltd, England) with resistivity ~ 15 - 16 MΩcm. Buffers were prepared by using phosphoric acid (H 3 PO 4 ), potassium dihydrogen orthophosphate (KH 2 PO 4 ), di-potassium hydrogen phosphate anhydrous (K 2 HPO 4 ), potassium hydrogen