期刊
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
卷 1764, 期 6, 页码 1000-1006出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbapap.2006.01.005
关键词
enzyme; decarboxylase; globular; protein; polymer; crowding
资金
- Wellcome Trust Funding Source: Medline
We have studied the effect of a crowded (macromolecular) solution on reaction rates of the decarboxylating enzymes urease, pyruvate decarboxylase and glutamate decarboxylase. A variety of crowding agents were used including haemoglobin, lysozyme, various dextrans and polyethylene glycol. Enzyme reaction rates of all three enzymes show two different types of effect that separate the globular proteins from the polysaccharides/polymers. Increasing concentration of globular proteins caused a dramatic rise in enzyme activity up to 30% crowding concentration then the activity decreased, whereas the polymers caused a concentration dependent decrease in activity. The viscosities of the globular proteins were low compared to the polymers. The increased activity with proteins may be due to the decreased amount of free water, which leads to higher effective concentration of substrates, or to an increased oligomeric state by self-association. The lower activities of all enzymes with all agents at high concentrations may be explained by a decrease in rates of diffusion. An increase in protein crowding (decrease in cell water content) may contribute to pathological conditions including cataract and Alzheimer's disease. (c) 2006 Elsevier B.V All rights reserved.
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