1.14.13.29	homotetramer	crystal structure analysis, the functional unit of PnpA1 is a tetramer, overview	-, 763974	
1.14.13.29	additional information	the PnpA1 monomer consists of 15 alpha-helices, 13 beta-strands, and four 310 helices and can be divided into three sequential segments based on their constituent secondary structural elements. Those three segments are tightly interconnected in the three-dimensional structure. Moreover, they form three faces of the hydrophobic substrate pocket. The first segment (residues 1 to 147) is composed of six helices (alpha1 to alpha6) and three short beta-strands (beta1 to beta3). This area is located in the periphery of the tetramer and constitutes the inner side of the pocket. The second segment (residues 148 to 277) has eight beta-strands (b4 to b11). These beta-strands are arranged as a small beta-barrel. The third segment, namely, the C-terminal segment, is composed of 8 helices (alpha7 to alpha15) and 2 short beta-strands (beta12 and beta13). Six alpha-helices (alpha7, alpha8, alpha9, alpha11, alpha12, and alpha13) form a helix bundle, which is mainly maintained by hydrophobic interaction among them. This segment is located at the tetramerization interface and involved in interacting with neighboring subunits. Alpha14 and alpha15 are the most extensive two of the eight helices. They clearly protrude from the protein core and extend into the neighboring subunit. No electron density is observed for residues 162 to 168 and residues 506 to 528 because of their high flexibility, which is common among PnpA1's homologues	-, 763974	
1.14.13.29	tetramer	4 * x, gel filtration chromatography	698597	
1.14.13.29	tetramer	crystallization data	-, 763974