1avw: Difference between revisions

The Kunitz-type trypsin inhibitor from soybean (STI) consists of 181 amino, acid residues with two disulfide bridges. Its crystal structures have been, determined in complex with porcine pancreatic trypsin in two crystal forms, (an orthorhombic form at 1.75 A resolution and a tetragonal form at 1.9 A), and in the free state at 2.3 A resolution. They have been refined to, crystallographic R-values of 18.9%, 21.6% and 19.8%, respectively. The, three models of STI reported here represent a significant improvement over, the partial inhibitor structure in the complex, which was previously, determined at a nominal resolution of 2.6 A by the multiple isomorphous, replacement method. This study provides the first high-resolution picture, of the complex between a Kunitz-type proteinase inhibitor with its cognate, proteinase. Many of the external loops of STI show high B-factors, both in, the free and the complexed states, except the reactive site loop whose, B-factors are dramatically reduced upon complexation. The reactive site, loop of STI adopts a canonical conformation similar to those in other, substrate-like inhibitors. The P1 carbonyl group displays no out-of-plane, displacement and thus retains a nominal trigonal planar geometry. Modeling, studies on the complex between a homologous Kunitz-type trypsin inhibitor, DE-3 from Erythrina caffra and the human tissue-type plasminogen activator, reveal a new insight into the specific interactions which could play a, crucial role in their binding.

1AVW is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Glycine_max Glycine max] and [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with CA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Trypsin Trypsin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.4 3.4.21.4] Structure known Active Sites: AVE and IRY. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1AVW OCA].  

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