Boreskov

ADSORPTION OF RIBOSE NUCLEOTIDES ON MANGANESE OXIDES WITHVARIED Mn/O RATIO: IMPLICATION IN CHEMICAL EVOLUTIONKamaluddin and Brij BhushanDepartment of Chemistry, Indian Institute of Technology Roorkee,Roorkee‐ 247667(U.K.), IndiaPP‐15Transition metals are significantly more important as catalyst in the formation ofbiopolymers during the course of chemical evolution and origin of life. (Arora andKamaluddin, 2007; Arora et al. 2007; Arora and Kamaluddin 2009). Manganese exists indifferent oxidation states under different environmental conditions with respect to redoxpotential. Various forms of manganese oxides, namely, Manganosite (MnO), Bixbyite(Mn 2 O 3 ), Hausmannite (Mn 3 O 4 ) and Pyrolusite (MnO 2 ) were synthesized and their role inchemical evolution studied. Adsorption studies of ribose nucleotides, namely, 5'‐AMP, 5'‐GMP, 5'‐CMP, and 5'‐UMP on the above manganese oxides at neutral pH. Results of ourstudies suggest that highest binding if ribonucleotides occurred with Manganosite (MnO) ascompared to other manganese oxides. Oxides of Manganese having a lower Mn‐O ratioshowing higher binding affinity towards the ribonucleotides implies indirectly that suchoxides may have provided their surface onto which biomonomers could have concentratedthrough selective adsorption; thereby stressing upon the concept that activities of chemicalevolution were pronounced when the redox potential of the earth atmosphere was low andthe atmosphere was less oxidized. Purine nucleotides were adsorbed more in comparison tothat of the pyrimidines nucleotides under neutral conditions. Adsorption data obtainedfollowed Langmuir adsorption isotherm, X m and K L values were calculated. The nature of theinteraction and mechanism is elucidated by the infrared spectral studies conducted on themetal‐oxide and ribonucleotide‐metal‐oxide adducts.References[1]. Arora A. K, Kamaluddin (2007) Interaction of ribose nucleotides with zinc oxide and relevance in chemicalevolution. Colloids surf. A: Physicochemical and Engineering Aspect. 298(3): 186‐191.[2]. Arora AK, Tomar V, Aarti, Venkateswararao KT, Kamaluddin (2007) Hematite–Water system on Mars andits possible role in chemical evolution. Int. J. Astrobiol. 6(4): 267‐271.[3]. Arora AK, Kamaluddin (2009) Role of Metal Oxides in Chemical Evolution: Interaction of RiboseNucleotides with Alumina. Astrobiol. 9:165‐171.157