Publications by authors named "Masaki Kitagawa"
Harmuful proteins are usually synthesized as inactive precursors and are activated by proteolytic processing. l-Amino acid oxidase (LAAO) is a flavoenzyme that catalyzes the oxidative deamination of l-amino acid to produce a 2-oxo acid with ammonia and highly toxic hydrogen peroxide and, therefore, is expressed as a precursor. The LAAO precursor shows significant variation in size and the cleavage pattern for activation.
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- l-Lysine oxidase (LysOX) is an enzyme that specifically converts l-lysine into α-keto-ε-aminocaproate, producing ammonia and hydrogen peroxide, and exhibits strict substrate specificity compared to other amino acid oxidases.
- Researchers determined the structure of LysOX with l-lysine, revealing that specific hydrogen bonding and a narrow hole in the active site are key to its strict recognition of l-lysine.
- Mutations in key residues essential for l-lysine recognition showed altered substrate specificity, providing insights into the molecular mechanisms behind LysOX's unique selectivity, and indicating potential for designing other amino acid-specific oxidases.
[A case of gastrointestinal stromal tumor of the stomach arising from the muscularis mucosae].
Nihon Shokakibyo Gakkai Zasshi
December 2006
A 75-year-old man, in whom upper gastrointestinal endoscopy revealed a submucosal tumor in the greater curvature of the gastric angle, was hospitalized for further investigations. Since the tumor was shown to be located in the submucosal layer by endoscopic ultrasonography, we performed endoscopic mucosal resection. Pathological studies of the resected specimen revealed a gastrointestinal stromal tumor of the stomach.
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