In this paper,we report the results of a HF/6-31G** and B3LYP/6-31+G** computational investigation of the title reaction for the peptide bond synthesis catalyzed by a single adenine,guanine or uracil.Thus,the analysis of the geometry and energetics of the critical structures involved in this title reaction yields insight into the catalytic mode of action of RNA molecules.The imino form of adenine should not be considered as a prerequisite for A2451 to have function as a general acid-base catalyst.The other nucletides of RNA,guanine,cytosine,and uracil,have the similar general acid-base catalytic function and mechanism with those of adenine.
The electronic singlet vertical excited states of photosynthetic reaction center (PSRC) in Rhodopseudomonas (Rps.) viridis were investigated by ZINDO and INDO/S methods. The effects of the interactions of pigment-pigment and pigment-protein on the electronic excitations were examined. The calculation results showed that the interactions of pigment-pigment and pigment-protein play an important role in reasonably assigning the experimental absorption and circular dichroism (CD) spec-tra of PSRC in Rps. virids. By comparing the theoretically computed excited states with the experi-mental absorption and CD spectra, satisfactory assignments of the experimental spectroscopic peaks were achieved.
REN Yanliang CHENG Lin WAN Jian LI Yongjian LIU Junjun YANG Guangfu ZHANG Lihua YANG Song
