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Purification and characterization of ornithine transcarbamylase from pea (Pisum sativum L.)Pea (Pisum sativum) ornithine transcarbamylase (OTC) was purified to homogeneity from leaf homogenates in a single-step procedure, using delta-N-(phosphonacetyl)-L-ornithine-Sepharose 6B affinity chromatography. The 1581-fold purified OTC enzyme exhibited a specific activity of 139 micromoles citrulline per minute per milligram of protein at 37 degrees C, pH 8.5. Pea OTC represents approximately 0.05% of the total soluble protein in the leaf. The molecular weight of the native enzyme was approximately 108,200, as estimated by Sephacryl S-200 gel filtration chromatography. The purified protein ran as a single molecular weight band of 36,500 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results suggest that the pea OTC is a trimer of identical subunits. The overall amino acid composition of pea OTC is similar to that found in other eukaryotic and prokaryotic OTCs, but the number of arginine residues is approximately twofold higher. The increased number of arginine residues probably accounts for the observed isoelectric point of 7.6 for the pea enzyme, which is considerably more basic than isoelectric point values that have been reported for other OTCs.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Slocum, R. D.
(Williams College Williamstown, Massachusetts 01267)
Richardson, D. P.
Date Acquired
August 21, 2013
Publication Date
January 1, 1991
Publication Information
Publication: Plant physiology
Volume: 96
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
Non-NASA Center
NASA Discipline Plant Biology
NASA Program Space Biology
NASA Discipline Number 40-50

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