© 2006 The Japanese Biochemical Society.
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Paenidase, a Novel D-Aspartyl Endopeptidase from Paenibacillus sp. B38: Purification and Substrate Specificity
1 Akita Research Institute of Food and Brewing, 4-26 Sanuki, Arayamachi, Akita 010-1623; and 2 Department of Biochemistry, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543
* To whom correspondence should be addressed. Tel: +81-18-888-2000, Fax: +81-18-888-2008, E-mail: saori{at}arif.pref.akita.jp
We discovered and characterized a novel type D-aspartyl endopeptidase (DAEP) produced extracellarly by Paenibacillus sp. B38. This bacterial DAEP of Mr 34,798 (named paenidase) appeared to be converted into a smaller form of Mr 34,169 by the proteolytic removal of 5 amino acid residues from the N-terminal. The intact and modified forms of the enzyme displayed essentially the same enzymatic properties. The enzyme specifically hydrolyzed succinyl-D-aspartic acid 
-(p-nitroanilide) and succinyl-D-aspartic acid -(4-methylcoumaryl-7-amide) to generate p-nitroaniline and 7-amino-4-methylcoumarin, and internally cleaved a synthetic peptide (D-A-E-F-R-H-[D-Asp]-G-S-Y) of the [D-Asp]7 amyloid ß (Aß) protein between [D-Asp]7-G8. Either was totally inert to the normal Aß peptide sequence containing L-Asp, instead of D-Asp at the 7th position. Thus, paenidase is the first DAEP from a microorganism that specifically recognizes an internal D-Asp residue to cleave [D-Asp]-X peptide bonds.