| Properties of D-xylose isomerase from Streptomyces albus. | |
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MedLine Citation:
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PMID: 239628 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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A partially purified D-xylose isomerase has been isolated from cells of Streptomyces albus NRRL 5778 and some of its properties have been determined. D-Glucose, D-xylose, D-ribose, L-arabinose, and L-rhamnose served as substrates for the enzyme with respective Km values of 86, 93, 350, 153, and 312 mM and Vmax values measuring 1.23, 2.9, 2.63, 0.153, and 0.048 mumol min per mg of protein. The hexose D-allose was also isomerized. The enzyme was strongly activated by 1.0 mM Mg2+ but only partially activated by 1.0 mM Co2+. The respective Km values for Mg2+ and Co2+ were 0.3 and 0.003 mM. Mg2+ and Co2+ appear to have separate binding sites on the isomerase. These cations also protect the enzyme from thermal denaturation and from D-sorbitol inhibition. The optimum temperature for ketose formation was 70 to 80 C at pH values ranging from 7 to 9. D-Sorbitol acts as a competitive inhibitor with a Ki of 5.5 mM against D-glucose, D-xylose, and D-ribose. Induction experiments, Mg2+ activation, and D-sorbitol inhibition indicated that a single enzyme (D-xylose isomerase) was responsible for the isomerization of the pentoses, methyl pentose, and glucose. |
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Authors:
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S Sanchez; K L Smiley |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Applied microbiology Volume: 29 ISSN: 0003-6919 ISO Abbreviation: Appl Microbiol Publication Date: 1975 Jun |
Date Detail:
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Created Date: 1975-11-06 Completed Date: 1975-11-06 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 7605802 Medline TA: Appl Microbiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 745-50 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Arabinose
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metabolism Carbohydrate Epimerases* / metabolism Cell-Free System Cobalt / pharmacology Enzyme Activation Glucose / metabolism Hydrogen-Ion Concentration Magnesium / pharmacology Rhamnose / metabolism Ribose / metabolism Soil Microbiology* Sorbitol / pharmacology Stereoisomerism Streptomyces / enzymology* Temperature Xylose / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Xylose; 10485-94-6/Rhamnose; 147-81-9/Arabinose; 50-69-1/Ribose; 50-70-4/Sorbitol; 50-99-7/Glucose; 7439-95-4/Magnesium; 7440-48-4/Cobalt; EC 5.1.3.-/Carbohydrate Epimerases |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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