ISSN:
1432-072X
Keywords:
Cyanophycin granule polypeptide
;
Multi-L-arginyl-poly (L-aspartic acid)
;
Proteolytic enzyme
;
Protease
;
Cyanobacteria
;
Blue-green algae
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract An assay was developed to measure the proteolysis of cyanophycin granule polypeptide in crude extracts of a unicellular cyanobacterium. The substrate was radioactively labeled cyanophycin granule polypeptide formed by an unicellular cyanobacterium grown in the presence of chloramphenicol. Substrate polypeptide displayed identical chemical properties with polypeptide isolated from non-chloramphenicol-treated cells. Solubilization of radioactivity as arginine indicated hydrolysis of polypeptide. Radioactively labeled aspartate and arginine from hydrolyzed polypeptide was related to nmol amino acid using a combination of paper chromatography, liquid scintillation analysis, and ninhydrin quantitation. Protease activity was found in extracts of nitrogen-limited cells harvested 16–24 h after a nitrogen source was added back. Optimal pH for protease activity was 8.0 and optimum temperature was 35°C. Protease activity in crude extracts followed Michaelis-Menten kinetics with a V max of 92 nmol arginine per 15 min/mg protein and a K m of 2.1×103 nmol arginine. Protease activity was inhibited by arginine and by high concentrations of aspartate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00413011
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