Characterization of an Aminopeptidase from Grapes

The aminopeptidase activities from grapes,Vitis labruscanaB. Takasumi, increased parallel to the developmental stages and were, in order of activity, high for Phe‐, Leu‐, and Met‐p‐nitroanilides (aminoacyl‐NAs). The activities were concentrated in the hypodermis from fully ripe grapes rather than in...

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Bibliographic Details
Published in:International journal of plant sciences 1999-03, Vol.160 (2), p.299-306
Main Authors: Kang, Han‐Chul, Hahn, Tae‐Ryong, Chung, In‐Sik, Park, Jong‐Cheon
Format: Article
Language:English
Subjects:
Amino acids
Anatomy & physiology
Chromatography
Enzyme activity
Enzymes
Fruits
Gels
Hydrolysis
Hypodermis
Peptides
Potassium phosphates
Reagents
Ripening
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Summary:The aminopeptidase activities from grapes,Vitis labruscanaB. Takasumi, increased parallel to the developmental stages and were, in order of activity, high for Phe‐, Leu‐, and Met‐p‐nitroanilides (aminoacyl‐NAs). The activities were concentrated in the hypodermis from fully ripe grapes rather than in the flesh (mesocarp and placental tissue) or seeds. The rapid hydrolysis of the substrates was a common characteristic of the hypodermis of other strains, indicating that Phe‐specific aminopeptidase may play an important role in the hypodermis. An aminopeptidase was purified over 130‐fold from the hypodermis. The enzyme is a monomer of ca. 71–74 kDa as determined by SDS‐PAGE and Sephacryl S‐200 chromatography. The purified aminopeptidase, as well the crude extracts from whole grape and hypodermis, hydrolyzed aminoacyl‐NAs with nonpolar side chains such as Phe and Leu more efficiently. The order of activity was similar to the crude extract of the hypodermis, indicating that the enzyme may be a major aminopeptidase in the hypodermis. The enzyme had a pH optimum of 7.0. The increase of activity up to pH 7.0 seems to be correlated with the increase in pH in the hypodermis during ripening. N‐terminal‐blocked Phe‐ and some oligopeptidyl‐NAs as well as azocasein were not hydrolyzed. Phenylmethylsulfonyl fluoride and N‐ethylmaleimide inhibited the enzyme in concentration‐ and time‐dependent manners. To some extent, aprotinin selectively decreased the activity. The enzyme was neither significantly influenced by some metal ions nor inhibited by EDTA or 1,10‐phenanthroline.
ISSN:1058-5893
1537-5315
DOI:10.1086/314132