The predicted structure is indicative of protein function: the presence of conserved active sites and binding surfaces is useful in providing hypotheses about the function.
After 30 min incubation on ice and centrifugation (10,000 g for 10 min at 4°C), supernatant was diluted in a binding buffer (100 mM Tris and 0.1% TritonX100 at pH 8.0) to a final protein concentration of 0.1 µg/µL, and 100 µL of this suspension was applied to Q10 anion-exchange active binding surfaces of SELDI ProteinChip Arrays (Bio-Rad, Marnes-La-Coquette, France).
Arg227 defines a portion of the concave saccharide-binding surface of the active site.
Because methotrexate has more than twice the molecular weight of l-fuconate, a truncation of the "20s" loop, such as that seen in the β isoform, could expose a larger binding surface to accommodate methotrexate in the active site.
The N-terminal α/β-domain, three-helix bundle, and the β−2 and β−3 domains form the "core" of SpGH38 with all of these domains contributing to the active center and substrate binding surface.
After binding surface nucleolin, HB-19 enters cells by an active process and accumulates in the cytoplasm but it does not cross the nuclear membrane in contrast to physiological ligands of surface-nucleolin [11], [13], [14].
We hypothesize that this additional sequence at the binding surface is a defining feature of cellulose-active AA10 enzymes, paralleling the identification of a loop-modulating reaction specificity in the AA9 enzymes [ 21].
After binding surface nucleolin, HB-19 enters cells by an active process but it does not cross the nuclear membrane.
It remains unclear how the highly conserved caleosin isoforms execute several diverse functions that may require a well-structured active site for enzymatic reaction and a well-featured binding surface for specific protein protein interaction.
The structure of the tail-domain of CifPl and CifBp presents an extensive surface area adjacent to the active site suggestive of a binding surface for interaction with a specific substrate (see Fig. 2(b), 3 and 4).
