• R Nagaraj

      Articles written in Journal of Chemical Sciences

    • Solid phase synthesis of the signal sequence ofE. coli alkaline phosphatase

      G Laxma Reddy R Nagaraj

      More Details Abstract Fulltext PDF

      A synthetic peptide corresponding to the signal sequence ofE. coli alkaline phosphatase has been synthesized by the solid phase method employing the transesterification method of cleavage from the resin. The protected peptide obtained after cleavage was purified to homogeneity by column chromatography on silica gel, followed by partition chromatography on SephadexLH-20 using organic solvents like chloroform and methanol as eluants.

    • Role of the hydrophobic region of signal sequences in the targeting of proteins to membranes and translocation across the hydrophobic membrane barrier

      R Nagaraj

      More Details Abstract Fulltext PDF

      Proteins destined for regions other than the cytoplasm in cells have to cross at least one membrane barrier before reaching their proper destination. Almost all such proteins are initially biosynthesized as precursors with signal sequences at the amino terminus. Signal sequences are essential and also sufficient for proteins to be targeted to membranes and also for translocation across membranes. One striking feature that is clearly evident amongst signal sequences of secretory proteins is a positively charged amino terminus followed by a region comprising 10–12 very hydrophobic amino acids. The structural and physico-chemical properties of signal sequences have been analysed. On the basis of the analyses it is proposed that the structural feature of a positively charged amino terminal region followed by a hydrophobic stretch of amino acids, rather than a conformational one, is recognised by components of the cells export machinery. It is also postulated that signal sequences insert in the lipid bilayer of the translocation competent membrane after targeting. The presence of the signal sequence results in the formation of local ‘defects’ in the bilayer which have a role in translocation of proteins across membranes.

    • Manual solid-phase syntheses of peptides on resins with high loading capacity requiring small volumes of solvents

      E Bikshapathy R Nagaraj

      More Details Abstract Fulltext PDF

      The synthesis of peptides by manual solid-phase methods requiring very small volume of solvents at different steps is described. The syntheses have been carried out on polystyrene-based resins using fluorenylmethoxy carboxyl chemistry. All reactions were carried out in vials, of capacity 1.2 or 6 ml, with gentle stirring. The volumes of solvents used were 1–2 ml for each operation. The crude peptides after cleavage from the resin were reasonably pure. The total volume of solvents required for the entire synthesis is substantially less as compared to volumes required in semi-automated and fully automated peptide synthesizers which renders the described method cost-effective.

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