1IW4

Solution structure of ascidian trypsin inhibitor

Summary for 1IW4

• Entry DOI: 10.2210/pdb1iw4/pdb
• NMR Information: BMRB: 5348
• Descriptor: trypsin inhibitor (1 entity in total)
• Functional Keywords: solution structure, ascidian, trypsin inhibitor, cystine-stabilized alpha-helical motif, disulfide bond, kazal-type inhibitor, protein binding
• Biological source: Halocynthia roretzi
• Total number of polymer chains: 1
• Total formula weight: 6084.98

Authors

Hemmi, H.,Yoshida, T.,Kumazaki, T.,Nemoto, N.,Hasegawa, J.,Nishioka, F.,Kyogoku, Y.,Yokosawa, H.,Kobayashi, Y. (deposition date: 2002-04-19, release date: 2002-08-28, Last modification date: 2024-10-09)

Primary citation

Hemmi, H.,Yoshida, T.,Kumazaki, T.,Nemoto, N.,Hasegawa, J.,Nishioka, F.,Kyogoku, Y.,Yokosawa, H.,Kobayashi, Y.
Solution structure of ascidian trypsin inhibitor determined by nuclear magnetic resonance spectroscopy.
Biochemistry, 41:10657-10664, 2002

PubMed Abstract: The three-dimensional solution structure of ascidian trypsin inhibitor (ATI), a 55 amino acid residue protein with four disulfide bridges, was determined by means of two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy. The resulting structure of ATI was characterized by an alpha-helical conformation in residues 35-42 and a three-stranded antiparallel beta-sheet in residues 22-26, 29-32, and 48-50. The presence of an alpha-helical conformation was predicted from the consensus sequences of the cystine-stabilized alpha-helical (CSH) motif, which is characterized by an alpha-helix structure in the Cys-X(1)-X(2)-X(3)-Cys portion (corresponding to residues 37-41), linking to the Cys-X-Cys portion (corresponding to residues 12-14) folded in an extended structure. The secondary structure and the overall folding of the main chain of ATI were very similar to those of the Kazal-type inhibitors, such as Japanese quail ovomucoid third domain (OMJPQ3) and leech-derived tryptase inhibitor form C (LDTI-C), although ATI does not show extensive sequence homology to these inhibitors except for a few amino acid residues and six of eight half-cystines. On the basis of these findings, we realign the amino acid sequences of representative Kazal-type inhibitors including ATI and discuss the unique structure of ATI with four disulfide bridges.

PubMed: 12186551
DOI: 10.1021/bi026035o

Experimental method

SOLUTION NMR