PMC

Gelling behavior of 5% (wt/wt) solutions of PyTSP (triangles), potato starch (circles), and gelatin bloom 250 (crosses). Samples were incubated in a rheometer at 4°C.

Side chain distribution of debranched native potato starch (lower panel) and debranched PyAMase-produced thermoreversible starch product (upper panel), as determined by HPLC.

Temperature dependence of the activity of PyAMase and corresponding Arrhenius plot (inset). Assays were performed with 10 mM G3 in 25 mM sodium citrate-25 mM NaP_i buffer, pH 7.5.

Ribbon presentation of 3D model of PyAMase. Catalytic residues Asp271, Glu318, and Asp371 are indicated with stick representation. Cysteine residues are indicated with space-filling representation. The picture was generated in Swiss-PDBViewer 3.7 () and visualized using Pov-Ray for Windows 3.5 ().

Schematic representation of annotated open reading frames in the P. aerophilum genome sequence between positions 704000 and 715000 (). The amylomaltase-encoding gene (1209) is indicated in black. Genes encoding members of the paREP2 family (1201 and 1211 to 1215) are indicated in gray. Other genes encode a putative spermidine synthetase (1203), a panthothenate metabolism flavoprotein (1204), and hypothetical proteins (1205 and 1208).

Relative gel strength of thermoreversible starch gels produced with PyAMase, as determined using the gel compression test (assay details are given in Materials and Methods). Numbers on the x axis indicate the units of PyAMase activity per gram of starch, with the incubation time at 80°C in hours in parentheses.

Unrooted phylogenetic tree of amylomaltase amino acid sequences. The amylomaltase sequences used to construct the tree have the following sequence identifiers (GI): Aquifex aeolicus, 2983306; Arabidopsis thaliana, 15238289; Chlamydomonas reinhardtii, 11095335; Clostridium perfringens, 18146003; Desulfovibrio desulfuricans, 23475749; Geobacter metallireducens, 23056370; Geobacter sulfurreducens, 39983164; Nostoc sp., 17133005; Oryza sativa, 22093785; Pirellula sp., 32397617; Pyrobaculum aerophilum, 18159937; Solanum tuberosum, 296692; Streptococcus mutans, 24377932; Thermus thermophilus, 37654050; and Treponema denticola, 41818933. All sequences are from bacterial origins, except those indicated with an asterisk or shown in bold, which are from eukaryal and archaeal origins, respectively. Nodes supported by bootstrap probabilities of >70% are marked by circles.