How Accurate Must Potentials Be for Successful Modeling of Protein Folding?

Protein sequences are believed to have been selected to provide the stability of, and reliable renaturation to, an encoded unique spatial fold. In recently proposed theoretical schemes, this selection is modeled as ``minimal frustration,'' or ``optimal energy'' of the desirable target conformation over all possible sequences, such that the ``design'' of the sequence is governed by the interactions between monomers. With replica mean field theory, we examine the possibility to reconstruct the renaturation, or freezing transition, of the ``designed'' heteropolymer given the inevitable errors in the determination of interaction energies, that is, the difference between sets (matrices) of interactions governing chain design and conformations, respectively. We find that the possibility of folding to the designed conformation is controlled by the correlations of the elements of the design and renaturation interaction matrices; unlike random heteropolymers, the ground state of designed heteropolymers is sufficiently stable, such that even a substantial error in the interaction energy should still yield correct renaturation.Comment: 28 pages, 3 postscript figures; tared, compressed, uuencode

Freezing Transition of Random Heteropolymers Consisting of an Arbitrary Set of Monomers

Mean field replica theory is employed to analyze the freezing transition of random heteropolymers comprised of an arbitrary number ($q$) of types of monomers. Our formalism assumes that interactions are short range and heterogeneity comes only from pairwise interactions, which are defined by an arbitrary $q \times q$ matrix. We show that, in general, there exists a freezing transition from a random globule, in which the thermodynamic equilibrium is comprised of an essentially infinite number polymer conformations, to a frozen globule, in which equilibrium ensemble is dominated by one or very few conformations. We also examine some special cases of interaction matrices to analyze the relationship between the freezing transition and the nature of interactions involved.Comment: 30 pages, 1 postscript figur

Reductive Biotransformation of Ethyl Acetoacetate: A Comparative Studies using Free and Immobilized Whole Yeast Cells

Bioreduction of ethyl acetoacetate with free and immobilized yeast whole cell was achieved by using water and sucrose combination. After detachment from immobilized beads under basic condition, the corresponding ethyl(S)-(+)-3-hydroxybutanoate was isolated with 98 to 100% yield. Immobilized beads of yeast whole cell were prepared at different temperature which affects the morphology and physiology of the beads for the diffusion of the enzyme, which shown the maximum conversion of the substrate to products as compared to the free yeast whole cell

Performance of hymenopteran insects as pollinators of pumpkin in Meghalaya

Pumpkin is a major cultivated crop particularly in north eastern states of India that depends on insects for the pollination, as the pollens of these plants are large sized and sticky. In the present study, field and lab experiments were conducted to determine the efficiency of the pollinators of pumpkin based on their diversity, relativeabundance and foraging activity. Total four hymenopteran insect pollinators were observed in field viz., bumble bee, little honey bee, Indian honey bee and Digger bee. On the basis of abundance and relative abundance bumble bee was identified as most abundant pollinator of pumpkin with 69.69 per cent mean relative abundance as other pollinators mean relative abundance was less than 25 per cent and it was only 3.49 per cent for Indian honey bee. Foraging speed and foraging rate of bumble bee was 7.13 sec/flower and foraging rate was 3.80 flower/minute. To ensure the efficient pollinator of pumpkin flower, pollen carrying capacity, pollen deposition and percent deposition of viable pollen was studied for all the pollinators in field and laboratory condition. The pollen carrying capacity of pollinators ranged from more than 7 mg to 1 mg. It was highest for bumble bee which was 7.33 mg followed by little honey bee (6.66 mg) and least pollen carrying capacity was observed in Digger bee (1.67 mg). Pollen depositions by pollinators on stigma in a single visit was again highest for bumble bee (565 pollen grains) with maximum number of viable pollen deposition 224.33 pollen grains out of which 39.7 per cent pollen was viable. So on the basis of above result it can be concluded that bumble bee was the most abundant and most efficient pollinator of pumpkin

Prevalence of malnutrition and intestinal parasites in preschool slum children in Lucknow

Objective: To assess the point prevalence of intestinal parasites and their association with nutritional parameters. Setting: Anganwadi centers under the Integrated Child Development Scheme (ICDS) in Lucknow, North India. Design: Cross-sectional survey. Methods: By random draw, 32 out of 153 Anganwadi centers were selected. All eligible subjects registered with the Anganwadi worker were enrolled. These were 1061 children (48.3% girls and 51.7% boys) between the ages of 1.5 to 3.5 years. Results: Of these, 67.6% were underweight (weight for age <- 2 SD), 62.8% were stunted (height for age <-2 SD) and 26.5% were wasted (weight for height <-2 SD). Parasites were detected in 17.5% (95% CI 15.3%-19.9%) children by a single direct fecal smear examination. Of these, Ascaris lumbricoides was found in 124 (68.1%) and Giardia lamblia in 60 (32.9%). There was no association between weight or height and parasite positivity. The mean hemoglobin levels for children who were smear positive versus smear negative for ascaris or giardia were 9.1 g/dl and 9.6 g/dl, respectively (p<0.0001). Conclusion: In the urban slums the point prevalence of intestinal parasites is 17.5% in the preschool children. Malnutrition and low hemoglobin levels are also widely prevalent. Urgent remedial steps are needed on community basis to improve their nutritional status and control parasitic infestation

Dendrimer-Encapsulated Nanoparticles: New Synthetic and Characterization Methods and Catalytic Applications

In this article we describe the synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles (DENs). These materials are synthesized using a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently reduced chemically to yield nearly size-monodisperse particles having diameters in the 1-2 nm range. Monometallic, bimetallic (alloy and core@shell), and semiconductor nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticle replica, but also as a stabilizer for the nanoparticle. In this perspective, we report on progress in the synthesis, characterization, and applications of these materials since our last review in 2005. Significant advances in the synthesis of core@shell DENs, characterization, and applications to homogeneous and heterogeneous catalysis (including electrocatalysis) are emphasized.U.S. Department of Energy, Office of Basic Energy Sciences DE-FG02-09ER16090U.S. National Science Foundation 0847957Robert A. Welch Foundation F-0032Chemistr

Is Heteropolymer Freezing Well Described by the Random Energy Model?

It is widely held that the Random Energy Model (REM) describes the freezing transition of a variety of types of heteropolymers. We demonstrate that the hallmark property of REM, statistical independence of the energies of states over disorder, is violated in different ways for models commonly employed in heteropolymer freezing studies. The implications for proteins are also discussed.Comment: 4 pages, 3 eps figures To appear in Physical Review Letters, May 199