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The article studies the kinetics of glucoamylase-catalyzed hydrolysis of starch granules from six different botanical sources such as rice, wheat, maize, cassava, sweet potato and potato using an electrochemical glucose sensor. According to the authors, a higher rate of hydrolysis was obtained as a smaller size of starch granules was used. The authors also present a comparison of the catalytic constants of the adsorbed enzyme in relation to the crystalline structure of the starch granules.

Bacteria produce polycationic homopoly(amino acid)s, which are characterized by isopeptide backbones. Although the biological significance of polycationic homopoly(amino acid)s remains unclear, increasing attention has recently been focused on their potential use to achieve cellular internalization. Here, for the first time, we provide direct evidence that two representative bacterial polycationic isopeptides, ε-poly-l-α-lysine (ε-PαL) and ε-oligo-l-β-lysine (ε-OβL), were internalized into mammalian cells by direct cell-membrane penetration and then diffused throughout the cytosol. In this study, we used clickable ε-PαL and ε-OβL derivatives carrying a C-terminal azide group, which were enzymatically produced and then conjugated with a fluorescent dye to analyze subcellular localization. Interestingly, fluorescent proteins conjugated with the clickable ε-PαL or ε-OβL were also internalized into cells and diffused throughout the cytosol. Notably, a Cre recombinase conjugate with ε-PαL entered cells and mediated the Cre/loxP recombination, and ε-PαL was found to deliver a full-length IgG antibody to the cytosol and nucleus. Bacteria-derived polycationic homopoly(amino acid)s are reported for the first time to directly penetrate cell membrane and deliver proteins of interest into cells, representing a new type of cell penetrating peptides for intracellular delivery. [ABSTRACT FROM AUTHOR]

We describe a new colorimetric assay method using glucose oxidase (GOx) to detect ε-poly- l -lysine (εPL). This method uses εPL's remarkable effect of promoting the enzymatic reaction of GOx with ferricyanide ion. This reaction reduces ferricyanide ion to ferrocyanide ion, accompanied by a color change from yellow to colorless. In this colorimetric assay, the detection limit of εPL was estimated to be approximately 0.5 mg/L when purified εPL samples were used. εPL has usually been produced by a fermentation process using Streptomyces albulus species. The components of the culture broth showed interference effects against the assay method. However, due to the high sensitivity of the assay method for εPL, εPL could be detected in the culture broth without any pretreatment. The detectable concentration of εPL in the culture broth, c PL,ac , was estimated to be approximately 20 mg/L. By combining the Berlin blue reaction with this method, the c PL,ac was reduced to 10 mg/L. In light of the proposed method's simplicity and sensitivity, it could be useful for screening εPL synthetic enzymes and microorganisms. [ABSTRACT FROM AUTHOR]