ISSN:
1432-072X
Keywords:
Cyanobacterium
;
Cyanophycin
;
Nitrogen metabolism
;
N-Trifluoroacetyl n-butyl esters Synechocystis
;
Amino acid analysis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Gas chromatography-mass spectrometry studies of the nitrogen isotopic composition of the N-trifluoroacetyl n-butyl ester derivatives of the amino acids from isolated hydrolyzed cyanophycin from 15N-enriched cells led to two major findings: (1) the amino acid composition of this granular polypeptide, isolated using procedures optimized for extracting and purifying cyanophycin from cells in the stationary growth phase, varied with the culture growth condition; (2) the rate of incorporation of exogenous nitrate differed for each nitrogen atom of the amino acid constituents of cyanophycin or cyanophycin-like polypeptide. Arginine and aspartic acid were the principle components of cyanophycin isolated from exponentially growing cells and from light-limited stationary phase cells, with glutamic acid as an additional minor component. The cyanophycin-like polypeptide from nitrogen-limited cells contained only aspartic and glutamic acids, but no arginine. The glutamic acid content decreased and arginine content increased as nitrate was provided to nitrogen-limited cells. These cells rapidly incorporated nitrate at different rates at each cyanophycin nitrogen site: guanidino nitrogens of arginine〉aspartic acid 〉α-amino nitrogen of arginine〉glutamic acid. Little media-derived nitrogen was incorporated into cyanophycin of exponentially growing cells during one cellular doubling time.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00314469
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