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A two-dimensional potential energy surface was utilized to treat the proton transfer in acetylacetone (AA) and its α-halo derivatives: α-fluoro-(FAA), α-chloro-(ClAA), and α-bromo-acetylacetone (BrAA). This potential energy function, which couples O-H stretching and in-plane bending vibrations, was acquired through ab initio calculations for a fixed skeleton geometry. The resulting potential energy surfaces were then used to calculate the proton tunneling frequencies and proton transfer barrier heights. The barrier heights (the energy difference between the saddle point and the minima) calculated at the MP2/6-31G(2d,p) level of theory for proton transfers in AA, FAA, ClAA, and BrAA are 7.2, 9.4, 6.3, and 5.9 kcal mol(-1), respectively. The theoretically predicted proton transfer barrier heights exhibit excellent linear correlations with geometrical, electronic structural, and topological parameters evaluated by the atoms-in-molecule (AIM) and natural bond orbital (NBO) analyses.

Background and Aim:The drug resistance mutations are key elements in the failure of long-term treatment of Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) infections. The mutation in the YMDD motif in the P gene of HBV is the most critical factor in antiviral drug (especially lamivudine) resistance. This study aimed to assess the YMDD motif and other polymerase gene mutations in individuals with HBV/HIV coinfection. Materials and Methods:All enrolled patients were under lamivudine treatment. Blood samples were collected from 37 HBV/HIV-positive patients, and DNA was extracted. The P gene was amplified by the PCR method with appropriate primers. The PCR products for detecting mutations in the P gene were sent to the Macrogen. To investigate the P gene mutations, the obtained sequences were compared with the polymerase gene of the HBV standard sequence in the GeneBank (accession number AB033559). Results:The mean age of the patients was 34.1±5.7 years, of which 59.5% were male, and 40.5% were female. Of all patients, 56% were drug abusers, 35% had risky sexual behavior, 56% had prison history, and 33% had addicted wives. The 37 extracted samples were sequenced successfully. Among the studied samples (n =37), 28 patients had simultaneous mutations of YIDD and FLMAQ, 1 patient had YINN and FLIPH and 1 patient had YIDD and FSLAQ. Conclusion:In summary, drug-resistant variants were detectable in most coinfected patients with chronic Hepatitis B (CHB) and HIV. As a result of mutations, therapeutic strategies sometimes are not effective. Therefore, recognition and monitoring of drug resistance mutations are critical.

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