ISPUB.COM The Internet Journal of Genomics and Proteomics Volume 5 Number 1 1 of 10 Proteomic analysis and characterization of a novel glucansucrase from a newly isolated strain of Leuconostoc mesenteroides AA1 A Aman, S Ul Qader, S Bano, A Khan, A Azhar Citation A Aman, S Ul Qader, S Bano, A Khan, A Azhar. Proteomic analysis and characterization of a novel glucansucrase from a newly isolated strain of Leuconostoc mesenteroides AA1. The Internet Journal of Genomics and Proteomics. 2008 Volume 5 Number 1. Abstract PurposeGlucansucrase is an industrially important enzyme that is produced by different species of bacteria like Leuconostoc, Streptococcus and Acetobacter. Among them Leuconostoc mesenteroides is used for the production of glucansucrase that catalyzes the synthesis of a commercially important long chain glucose polymer known as glucan on industrial scale.Due to its increasing demand in various biotechnological industries, isolation of new strains of Leuconostoc mesenteroides for the production of glucansucrase and glucan is of valuable importance.MethodsNew strain of Leuconostoc mesenteroides AA1 was isolated and various biochemical conditions and aspects regarding extracellular glucansucrase activity have been optimized. Glucansucrase was purified to homogeneity using conventional chromatographic techniques. Amino acid analysis and N- Terminal sequence of the purified enzyme was also performed. Results Glucansucrase [EC 2.4.1.5] was purified to homogeneity with an overall purification factor of 162.5 times, with a specific activity of 2692 DSU/mg. The native protein showed a molecular mass of 177,000 Da by SDS PAGE. The enzyme exhibited optimum catalytic activity at 35°C and pH 5.0 with 0.1 M citrate phosphate buffer. The kinetic constants K m and V max were estimated as 69.88 mM and 61.75 DSU/ml/hr, respectively. The amino acid composition of the enzyme showed that the enzyme is rich in both the basic and polar/hydrophilic amino acid and is less rich in acidic amino acids. The first six amino acid residues at the N- terminal end are D-S-T-N-T-V. Conclusions This novel extracellular glucansucrase is significant for industrial perspective and is therefore suggested that this strain can be used for the production of glucansucrase and high molecular weight glucan on a large scale. Abbreviations: DSU, Dextransucrase Unit; SDS PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; PVDF, polyvinylidene difloride; HPLC, high performance liquid chromatography TrEMBL UniProtKB Accession #: P85080 E.C. 2.4.1.5 (glucosyltransferase) INTRODUCTION Glucansucrase is a glucosyltransferase (E.C. 2.4.1.5) that catalyzes the transfer of glucosyl residues from sucrose to glucan polymer and liberates fructose. Glucan is a high- molecular-mass polymer (10 7 to 10 8 Da) and composed of a linear chain of glucosyl residues all linked through α (1→6) glucosidic bond and several α (1→2), α (1→3), or α (1→4) branched linkages [ 12 ]. The frequency and nature of the branch points mainly depend on the origin of the glucansucrase (i.e., the producing microorganism) [ 3 ]. Glucansucrase can catalyze the synthesis of several types of linkages that leads to the formation of a branched polymer [ 45 ]. The enzyme responsible for the production of glucan (dextran) from sucrose is a glucansucrase, which belong to the family 70 of the glucosidases and transglycosidases in the CAZy classification [ 67 ]. Glucansucrase have broad applications in the biotechnology industries. They have made a remarkable impact in the world of biotechnology because of their applications in the food, cosmetic, agricultural, photography and fermentation industries. The most promising application of glucansucrase and glucan is their use as protective colloid in blood plasma volume expander, flocculation, stabilization, lyopholization