Plant Physiol.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Plant Physiology 97:606-612 (1991)
© 1991 American Society of Plant Biologists

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Web of Science (8)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Turano, F. J.
Right arrow Articles by Matthews, B. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Turano, F. J.
Right arrow Articles by Matthews, B. F.
Agricola
Right arrow Articles by Turano, F. J.
Right arrow Articles by Matthews, B. F.
Metabolism and Enzymology

Rapid Purification and Thermostability of the Cytoplasmic Aspartate Aminotransferase from Carrot Suspension Cultures 1

Frank J. Turano2, Barbara J. Wilson and Benjamin F. Matthews

United States Department of Agriculture, Agricultural Research Service, Plant Molecular Biology Laboratory, Beltsville, Maryland 20705

Several isoenzymic forms of aspartate aminotransferase (AAT) have been identified in protein extracts from carrot (Daucus carota) cell suspension cultures. The cellular location of the major form (form I) of AAT in carrot suspension cultures was determined by heat inactivation, subcellular fractionation, and amino acid sequence analysis. In mammalian systems, there are two forms of AAT, a heat-stable cytoplasmic form and a heat-labile form in the mitochondria. The thermostability of three isoenzymes of carrot AAT was examined, and the results showed that form I was more thermostable than forms II or III. Organelles were separated in sucrose gradients by isopynic centrifugation. Activity for form I was identified in the soluble fractions and not in fractions containing peroxisomes, proplastids, or mitochondria. Form I was purified to homogeneity and endoproteolytically cleaved, and the peptide fragments were separated by reverse phase chromatography. Analysis of the sequence data from two of the polypeptides showed that the amino acid identity of form I is more conserved to the animal cytoplasmic AAT than to animal mitochondrial AAT sequences. These data strongly suggest that form I of AAT from carrot is the cytoplasmic isoenzyme. Additionally, a rapid purification scheme for form I of AAT from carrot is presented using selective heat denaturation and anion-exchange chromatography.

2 Present address: U.S. Department of Agriculture, Agricultural Research Service, Climate Stress Laboratory, Beltsville, MD 20705.

1 This research was supported in part by the U.S. Department of Agriculture Competitive Grants Office (No. 87-CRCR-1-2284).






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 1991 by the American Society of Plant Biologists