Anomeric specificity and mechanism of two pentose isomerases

Schray, Keith J.; Rose, Irwin A.

doi:10.1021/bi00782a019

Cited by 89 publications

(43 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3). Thus, as observed (15,16), there can be no exchange of the hydride ion with solvent. Although there is no mechanistic requirement for a syn conformation at C'-C2, an approximate syn conformation is indicated by the electron density for this end of the substrate, bringing 01 and 02 close together in contact with the cation near site 2, and is consistent with the observed stereochemistry of hydride transfer (7,8).…”

Section: Resultsmentioning

confidence: 78%

See 1 more Smart Citation

Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.

Collyer

Blow

1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 78%

“…The sugar substrates of XI exist in solution predominantly in closed-ring forms, and XI acts and reacts specifically with the a-D-pyranose forms of xylose and glucose (15,16) (9). A square indicates the hydrogen atom that is transferred stereospecifically.…”

mentioning

confidence: 99%

Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.

Collyer

Blow

1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…This mutarotase function could link together xylose metabolism and xylan metabolism. The first enzyme in the xylose utilization pathway, xylose isomerase, has a marked preference for ␣-Dxylose over ␤-D-xylose (14,32). However, the end product of xylan breakdown is ␤-D-xylose.…”

mentioning

confidence: 99%

Genetic Evidence for a Defective Xylan Degradation Pathway in Lactococcus lactis

Erlandson

Delamarre

Batt

2001

Appl Environ Microbiol

View full text Add to dashboard Cite

“…1a). The currently accepted pathway for the reaction involves the preferential binding of ␣-Dxylopyranose (24,25) followed by ring opening (25), extension of the substrate, and then the hydride shift (15,16,26). Recently, Meng et al (27) have proposed that the hydride shift occurs on the cyclic form of sugar (Fig.…”

mentioning

confidence: 99%

Probing the Roles of Active Site Residues in D-Xylose Isomerase

Whitaker

Cho

Cha

et al. 1995

Journal of Biological Chemistry

View full text Add to dashboard Cite

Initially, a cis-enediol mechanism was proposed for D-xylose isomerase (14,22), similar to the mechanism of triose-phosphate isomerase. However, isotope exchange experiments (23) and crystallographic analyses (15, 16) with various substrates and inhibitors suggests that the reaction proceeds via a metalmediated hydride shift (Fig. 1a). The currently accepted pathway for the reaction involves the preferential binding of ␣-Dxylopyranose (24, 25) followed by ring opening (25), extension of the substrate, and then the hydride shift (15,16,26). Recently, Meng et al. (27) have proposed that the hydride shift occurs on the cyclic form of sugar (Fig. 1b).Site-directed mutagenesis has been used to probe the functions of specific active site residues in D-xylose isomerase (27-32), however, only a few structures of mutant enzymes have been reported (19,(33)(34)(35). Kinetic data can be misleading if the substitutions affect the properties of catalytically important residues other than those changed by mutagenesis. For this reason, we have shifted our mutagenic studies from the Escherichia coli D-xylose isomerase (28, 29), which has not been successfully crystallized, to the S. rubiginosus enzyme which readily forms crystals diffracting x-rays beyond 2.0 Å (15,34,36 MATERIALS AND METHODSBacterial Strains and Plasmids-S. rubiginosus (ATCC 21175) was obtained from the American Type Culture Collection. E. coli BL21(DE3) (F Ϫ ompT r B Ϫm B Ϫ ( cTts857 ind1 Sam7 nin5 lacUV5-T7 gene 1)) was from Novagen. E. coli TG1 (supE hsd ⌬5 thi ⌬(lac-proAB) FЈ (traD36 proAB ϩ lacI q lacZ ⌬M15)) was used to propagate plasmid and bacteriophage M13. M13 mp18 and M13 mp19 DNA were purchased from U. S. Biochemical Corp. and pET11d plasmid DNA was from Novagen. S. rubiginosus xylA cloned into pET11d is called pRDW100 (its construction is described below) and is regulated by T7 RNA polymerase and LacZ, using the strain BL21(DE3) as a host.Biochemical Reagents-All compounds were reagent grade and purchased from Sigma, except acetaldehyde and 5-thio-␣-D-glucopyranose (THG), 1 which were from Aldrich. The sugar 5-deoxy-D-xylulose was synthesized by aldol condensation of dihydroxyacetone and acetaldehyde, using rabbit muscle aldolase with the cofactor sodium arsenate as a catalyst, and was purified by ion-exchange chromatography, 2 using a scheme similar to that described by Durrwachter et al. (37) for the synthesis of 5-deoxy-D-fructose.DNA Isolation, Transformation, and Manipulations-S. rubiginosus was grown in yeast and maltose extract medium supplemented with 34% (w/v) sucrose and chromosomal DNA was isolated as Hopwood et al. (38). Both plasmid and bacteriophage DNA were isolated from cul-

show abstract

Anomeric specificity and mechanism of two pentose isomerases

Cited by 89 publications

References 17 publications

Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.

Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.

Genetic Evidence for a Defective Xylan Degradation Pathway in Lactococcus lactis

Probing the Roles of Active Site Residues in D-Xylose Isomerase

Contact Info

Product

Resources

About