Functional Role of Glutamine 28 and Arginine 39 in Double Stranded RNA Cleavage by Human Pancreatic Ribonuclease

Human pancreatic ribonuclease (HPR), a member of RNase A superfamily, has a high activity on double stranded (ds) RNA. By virtue of this activity HPR appears to be involved in the host-defense against pathogenic viruses. To delineate the mechanism of dsRNA cleavage by HPR, we have investigated the role of glutamine 28 and arginine 39 of HPR in its activity on dsRNA. A non-basic residue glycine 38, earlier shown to be important for dsRNA cleavage by HPR was also included in the study in the context of glutamine 28 and arginine 39. Nine variants of HPR respectively containing Q28A, Q28L, R39A, G38D, Q28A/R39A, Q28L/R39A, Q28A/G38D, R39A/G38D and Q28A/G38D/R39A mutations were generated and functionally characterized. The far-UV CD-spectral analysis revealed all variants, except R39A, to have structures similar to that of HPR. The catalytic activity of all HPR variants on single stranded RNA substrate was similar to that of HPR, whereas on dsRNA, the catalytic efficiency of all single residue variants, except for the Q28L, was significantly reduced. The dsRNA cleavage activity of R39A/G38D and Q28A/G38D/R39A variants was most drastically reduced to 4% of that of HPR. The variants having reduced dsRNA cleavage activity also had reduction in their dsDNA melting activity and thermal stability. Our results indicate that in HPR both glutamine 28 and arginine 39 are important for the cleavage of dsRNA. Although these residues are not directly involved in catalysis, both arginine 39 and glutamine 28 appear to be facilitating a productive substrate-enzyme interaction during the dsRNA cleavage by HPR

Measurement of the branching fraction for B−→D0K∗−B^- \to D^0 K^{*-}

We present a measurement of the branching fraction for the decay B- --> D0 K*- using a sample of approximately 86 million BBbar pairs collected by the BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the K*- through its decay to K0S pi-. We measure the branching fraction to be B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}

Observation of a significant excess of π0π0\pi^{0}\pi^{0} events in B meson decays

We present an observation of the decay $B^{0} \to \pi^{0} \pi^{0}$ based on a sample of 124 million $B\bar{B}$ pairs recorded by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We observe $46 \pm 13 \pm 3$ events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations including systematic uncertainties. We measure the branching fraction \BR(B^{0} \to \pi^{0} \pi^{0}) = (2.1 \pm 0.6 \pm 0.3) \times 10^{-6}, averaged over $B^{0}$ and $\bar{B}^{0}$ decays

Measurement of B-0 -> D-s(*)D+*(-) branching fractions and B-0 -> D-s*D+*(-) polarization with a partial reconstruction technique

We present a study of the decays B-0 --> D-s((*)) D*-, using 20.8 fb(-1) of e(+)e(-) annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D-s((*)+) and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B-0 --> Ds+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and B(B-0 --> D-s(*+) D*-) = (1.97 +/- 0.15 +/- 0.30+/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D-s(+) --> phipi(+) branching fraction uncertainty. From the B-0 --> D-s(*+) D*- angular distributions, we measure the fraction of longitudinal polarization Gamma(L)/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization

Search for the radiative decays B ->rho gamma and B-0 ->omega gamma

A search of the exclusive radiative decays B-->rho(770)gamma and B-0-->omega(782)gamma is performed on a sample of about 84x10(6) B (B) over bar events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions B of B(B-0-->rho(0)gamma)rho(+)gamma)omegagamma)rhogamma)=Gamma(B+-->rho(+)gamma)=2xGamma(B-0-->rho(0)gamma), we find the combined limit B(B-->rhogamma)rhogamma)/B(B-->K(*)gamma)<0.047 at 90% C.L

Search for D-0-(D)over-bar(0) mixing and a measurement of the doubly Cabibbo-suppressed decay rate in D-0 -> K pi decays

We present results of a search for D-0-(D) over bar (0) mixing and a measurement of R-D, the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, using D-0-->K(+)pi(-) decays from 57.1 fb(-1) of data collected near roots=10.6 GeV with the BABAR detector at the PEP-II collider. At the 95% confidence level, allowing for CP violation, we find the mixing parameters x('2)<0.0022 and -0.056<y(')<0.039, and the mixing rate R-M<0.16%. In the limit of no mixing, R-D=[0.357+/-0.022(stat)+/-0.027(syst)]% and the CP-violating asymmetry A(D)=0.095+/-0.061(stat)+/-0.083(syst)

Measurement of the branching fraction for B±→χc0K±

We present preliminary results for the measurement of the branching fraction of the decay B+- -> chi_c0 K+- from a sample of 75 million BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The chi_c0 meson is reconstructed through its two-body decays to pi+ pi- and K+ K-. We measure BR(B+- -> chi_c0 K+-) * BR(chi_c0 -> pi+ pi-) = (1.08 +- 0.35 (stat) +- 0.10 (syst))*10^-6 and BR(B+- -> chi_c0 K+-) * BR(chi_c0 -> K+ K-) = (1.48 +- 0.44 (stat) +- 0.17 (syst)) * 10^-6. Using the known values for the chi_c0 decays branching fractions, we combined these results to obtain BR(B+- -> chi_c0 K+-) = (2.4 +- 0.7) * 10^-4

Measurement of the branching fractions and CP asymmetry of B- -> (D(CP)K-)-K-0 decays with the BaBar detector

We present a study of B--->(DCPK-)-K-0 decays, where D-CP(0) is reconstructed in CP-even channels, based on a sample of 88.8x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions B(B--->(DCPK-)-K-0)/B(B--->D(CP)(0)pi(-))=[8.8+/-1.6(stat)+/-0.5(syst)]x10(-2) and the CP asymmetry A(CP)=0.07+/-0.17(stat)+/-0.06(syst). We also measure B(B--->(DK-)-K-0)/B(B--->D(0)pi(-))=[8.31+/-0.35(stat)+/-0.20(syst)]x10(-2) using a sample of 61.0x10(6) B (B) over bar pairs

Measurements of branching fractions and dalitz distributions for B-0 ->(DK0)-K-(*)+/-pi(-/+) decays

We present measurments of the branching fractions for the three-body decays B-0 -> D((*) -/+)K(0)pi(+/-) and their resonant submodes B0 -> D(*)K-/+*(+/-) usinga sample of approximately 88 x 10(6) B (B) over bar pairs collected by the BABER detector at the SLAC PEP-II assymetric energy storage ring. We measure: B(B-0-> D(-/+)K(0)pi(+/-)) = (4.9 +/- 0.7(stat) +/- 0.5(syst)) x 10(-4), B(B-0 -> D*(-/+)K(0)pi(+/-)) = (3.0 +/- 0.7(stat) +/- 0.3(syst)) x 10(-4), B(B-0 -> D-/+K*(+/-)) = (4.6 +/- 0.6(stat) +/- 0.5(syst)) x 10(-4), B(B-0 -> D*K-/+*(+/-) = (3.2 +/- 0.6(stat) +/- 0.3(syst)) x 10(-4). From these measurements we determine the fractions of resonant events to be f(B0 -> D+/-K*(-/+)) = 0.63 +/- 0.08(stat) +/- 0.04(syst) and f(B-0 -> D*K-/+*(+/-)) = 0.72 +/- 0.14(stat) +/- 0.05(syst)

Measurement of the branching fractions and CP asymmetry of B- -> (D(CP)K-)-K-0 decays with the BaBar detector

We present a study of B--->(DCPK-)-K-0 decays, where D-CP(0) is reconstructed in CP-even channels, based on a sample of 88.8x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions B(B--->(DCPK-)-K-0)/B(B--->D(CP)(0)pi(-))=[8.8+/-1.6(stat)+/-0.5(syst)]x10(-2) and the CP asymmetry A(CP)=0.07+/-0.17(stat)+/-0.06(syst). We also measure B(B--->(DK-)-K-0)/B(B--->D(0)pi(-))=[8.31+/-0.35(stat)+/-0.20(syst)]x10(-2) using a sample of 61.0x10(6) B (B) over bar pairs.The Particle Physics and Astronomy Research Council (United Kingdom); A. P. Sloan Foundation; the Research Corporation; and the Alexander von Humboldt Foundation