Publications

• Mutarotase from Penicillium notatum. I. Purification, assay, and general properties of the enzyme.

  BENTLEY R., BHATE D.S.

  J Biol Chem 235:1219-1224(1960) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Biological catalysis of mutarotation of glucose.

  KEILIN D., HARTREE E.F.

  Biochem J 50:341-348(1952) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Characterization of the proteins encoded by the Bacillus subtilis yoxA-dacC operon.

  Duez C., Zervosen A., Teller N., Melkonian R., Banzubaze E., Bouillenne F., Luxen A., Frere J.-M.

  In Bacillus subtilis, the yoxA and dacC genes were proposed to form an operon. The yoxA gene was overexpressed in Escherichia coli and its product fused to a polyhistidine tag was purified. An aldose-1-epimerase or mutarotase activity was measured with the YoxA protein that we propose to rename as ... >> More

  In Bacillus subtilis, the yoxA and dacC genes were proposed to form an operon. The yoxA gene was overexpressed in Escherichia coli and its product fused to a polyhistidine tag was purified. An aldose-1-epimerase or mutarotase activity was measured with the YoxA protein that we propose to rename as GalM by analogy with its counterpart in E. coli. The peptide D-Glu-delta-m-A(2)pm-D-Ala-m-A(2)pm-D-Ala mimicking the B. subtilis and E. coli interpeptide bridge was synthesized and incubated with the purified dacC product, the PBP4a. A clear dd-endopeptidase activity was obtained with this penicillin-binding protein, or PBP. The possible role of this class of PBP, present in almost all bacteria, is discussed. << Less

  FEMS Microbiol. Lett. 300:42-47(2009) [PubMed] [EuropePMC]

• Molecular structure of human galactose mutarotase.

  Thoden J.B., Timson D.J., Reece R.J., Holden H.M.

  Galactose mutarotase catalyzes the conversion of beta-d-galactose to alpha-d-galactose during normal galactose metabolism. The enzyme has been isolated from bacteria, plants, and animals and is present in the cytoplasm of most cells. Here we report the x-ray crystallographic analysis of human gala ... >> More

  Galactose mutarotase catalyzes the conversion of beta-d-galactose to alpha-d-galactose during normal galactose metabolism. The enzyme has been isolated from bacteria, plants, and animals and is present in the cytoplasm of most cells. Here we report the x-ray crystallographic analysis of human galactose mutarotase both in the apoform and complexed with its substrate, beta-d-galactose. The polypeptide chain folds into an intricate array of 29 beta-strands, 25 classical reverse turns, and 2 small alpha-helices. There are two cis-peptide bonds at Arg-78 and Pro-103. The sugar ligand sits in a shallow cleft and is surrounded by Asn-81, Arg-82, His-107, His-176, Asp-243, Gln-279, and Glu-307. Both the side chains of Glu-307 and His-176 are in the proper location to act as a catalytic base and a catalytic acid, respectively. These residues are absolutely conserved among galactose mutarotases. To date, x-ray models for three mutarotases have now been reported, namely that described here and those from Lactococcus lactis and Caenorhabditis elegans. The molecular architectures of these enzymes differ primarily in the loop regions connecting the first two beta-strands. In the human protein, there are six extra residues in the loop compared with the bacterial protein for an approximate longer length of 9 A. In the C. elegans protein, the first 17 residues are missing, thereby reducing the total number of beta-strands by one. << Less

  J. Biol. Chem. 279:23431-23437(2004) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Cloning and expression of the Acinetobacter calcoaceticus mutarotase gene in Escherichia coli.

  Gatz C., Altschmied J., Hillen W.

  This article describes the cloning of the mutarotase gene from Acinetobacter calcoaceticus and its expression in Escherichia coli. Purification of mutarotase (EC 5.1.3.3) led to a single polypeptide of 40 kilodaltons. The sequences of 27 N-terminal and 76 C-terminal amino acids were determined. Fr ... >> More

  This article describes the cloning of the mutarotase gene from Acinetobacter calcoaceticus and its expression in Escherichia coli. Purification of mutarotase (EC 5.1.3.3) led to a single polypeptide of 40 kilodaltons. The sequences of 27 N-terminal and 76 C-terminal amino acids were determined. From six amino acids of the N-terminal and seven amino acids of the C-terminal portion of the protein, the sequences of two oligonucleotides were deduced. These were synthesized and used as gene probes. Completely restricted chromosomal DNA from A. calcoaceticus was size fractioned, and only fractions hybridizing with the gene probes were used to construct gene banks enriched for the mutarotase determinant. With the N-terminal gene probe, a bank of 6-to 7-kilobase-pair BclI fragments in pBR327 was obtained. A total of 1,200 candidates were screened by colony hybridization followed by dot-blot analysis of purified plasmids from positive candidates and subsequent Southern blot analysis of the respective restricted plasmids, and 500 base pairs (bp) from the 5' end of the mutarotase gene were isolated by this procedure. The 3' portion of the gene was isolated from a gene bank containing 1,500-bp-long HindIII fragments inserted in M13mp11. This bank was screened by dot-blot analysis of single-stranded phage DNA with the C-terminal gene probe. The isolated gene fragments were fused at a common restriction site in their overlapping region to yield the complete mutarotase gene. High-level expression of mutarotase in E. coli was achieved when the gene was placed under transcriptional control of the phage lambda promoter pL. More than 90% of mutarotase activity was found in the culture medium. The E. coli-derived mutarotase was purified and shown to be identical to the A. calcoaceticus-derived product with respect to the molecular weight and N-terminal amino acid sequence. The expression of mutarotase in E. coli was increased 200-fold in comparison to that the wild-type A. calcoaceticus. << Less

  J. Bacteriol. 168:31-39(1986) [PubMed] [EuropePMC]

• Catecholamine-induced cardiac hypertrophy in a denervated, hemodynamically non-stressed heart transplant.

  Larson D.F., Copeland J.G., Russell D.H.

  Studies of stress-induced cardiac hypertrophy suggest that myocardial mass is regulated by the circulating level of epinephrine. The trophic effect is mediated by cardiac beta-adrenergic receptors, and in the murine, rat, and dog heart, specifically by beta 2-adrenergic receptors. The well-charact ... >> More

  Studies of stress-induced cardiac hypertrophy suggest that myocardial mass is regulated by the circulating level of epinephrine. The trophic effect is mediated by cardiac beta-adrenergic receptors, and in the murine, rat, and dog heart, specifically by beta 2-adrenergic receptors. The well-characterized functional effects of catecholamines on heart have obscured their role as myocardial trophic hormones. Therefore, we compared the effect of beta-adrenergic receptor stimulation on the myocardial mass of both a working innervated heart and an essentially nonworking denervated heterotopically transplanted heart in the same rat; in this model, the neural and stretch parameters are nonoperational in the transplanted heart. Ornithine decarboxylase (ODC), an enzyme elevated in a dose-dependent manner in heart by isoproterenol, was assayed in both hearts to determine the relationship between ODC activity and myocardial mass in response to isoproterenol administration in working, innervated heart compared to denervated, nonworking heart. In both recipient and donor heart, the myocardial mass paralleled the ability of an isoproterenol bolus to stimulate ODC in the respective heart. However, beta-adrenergic receptor activity in the donor heart was decreased 5 days after transplantation as assessed by the differential ability of a single dose of isoproterenol to stimulate ODC activity. Beta-receptor coupling to ODC activity in the donor heart exceeded that of the recipient heart at 10 days posttransplantation suggesting a time-dependent elevation of beta-adrenergic receptor activity in donor heart. At all times, alterations in myocardial mass paralleled beta-adrenoceptor activity as assessed by the ability of isoproterenol administration to elevate ODC activity. The results support the concept that myocardial mass is regulated by the level of circulating hormones, particularly epinephrine. << Less

  Life Sci 36:2477-2489(1985) [PubMed] [EuropePMC]

• Galactose mutarotase: purification, characterization, and investigations of two important histidine residues.

  Beebe J.A., Frey P.A.

  Galactose mutarotase catalyzes the interconversion of alpha- and beta-anomers of aldoses and is a recently identified member of the gal operon of Escherichia coli and participant in the Leloir pathway [Bouffard et al. (1994) J. Mol. Biol. 244, 269-278]. We report the purification and characterizat ... >> More

  Galactose mutarotase catalyzes the interconversion of alpha- and beta-anomers of aldoses and is a recently identified member of the gal operon of Escherichia coli and participant in the Leloir pathway [Bouffard et al. (1994) J. Mol. Biol. 244, 269-278]. We report the purification and characterization of this enzyme, as well as mechanistic studies involving chemical modification with diethylpyrocarbonate (DEPC) and site-directed mutagenesis demonstrating the significance of two conserved histidine residues. The enzyme lacks metal ions and oxidoreduction cofactors, and an extinction coefficient of (6.2 +/-0.4) x 10(4) M-1 cm-1 has been measured by quantitative amino acid analysis. The catalytic mechanism is likely concerted general acid/general base. Experiments involving modification with DEPC suggest that a histidine is essential and is protected by substrate. Furthermore, site-directed mutagenesis of two conserved histidines was performed, and characterization of these mutants (His104Gln and His175Asn) illustrates the significance of these residues. Kinetic analysis of H104Q demonstrates an increase in KM of about 600-fold, a decrease in kcat of approximately 7-fold, and a 4000-fold decrease in kcat/KM as compared to the wild-type enzyme. The activity of His175Asn mutant, on the other hand, was too low to be measured accurately, and His 175 remains a candidate for the general base. These mutants were also subjected to DEPC modification, and results are consistent with the presence of two important histidines positioned closely together in the active site. << Less

  Biochemistry 37:14989-14997(1998) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• The catalytic mechanism of galactose mutarotase.

  Thoden J.B., Kim J., Raushel F.M., Holden H.M.

  Galactose mutarotase catalyzes the first step in normal galactose metabolism by catalyzing the conversion of beta-D-galactose to alpha-D-galactose. The structure of the enzyme from Lactococcus lactis was recently solved in this laboratory and shown to be topologically similar to domain 5 of beta-g ... >> More

  Galactose mutarotase catalyzes the first step in normal galactose metabolism by catalyzing the conversion of beta-D-galactose to alpha-D-galactose. The structure of the enzyme from Lactococcus lactis was recently solved in this laboratory and shown to be topologically similar to domain 5 of beta-galactosidase. From this initial X-ray analysis, four amino acid residues were demonstrated to be intimately involved in sugar binding to the protein: His 96, His 170, Asp 243, and Glu 304. Here we present a combined X-ray crystallographic and kinetic analysis designed to examine the role of these residues in the reaction mechanism of the enzyme. For this investigation, the following site-directed mutant proteins were prepared: H96N, H170N, D243N, D243A, E304Q, and E304A. All of the structures of these proteins, complexed with either glucose or galactose, were solved to a nominal resolution of 1.95 A or better, and their kinetic parameters were measured against D-galactose, D-glucose, L-arabinose, or D-xylose. From these studies, it can be concluded that Glu 304 and His 170 are critical for catalysis and that His 96 and Asp 243 are important for proper substrate positioning within the active site. Specifically, Glu 304 serves as the active site base to initiate the reaction by removing the proton from the C-1 hydroxyl group of the sugar substrate and His 170 functions as the active site acid to protonate the C-5 ring oxygen. << Less

  Protein Sci 12:1051-1059(2003) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Mutarotase from Penicillium notatum. II. The mechanism of the mutarotation reaction.

  BENTLEY R., BHATE D.S.

  J Biol Chem 235:1225-1233(1960) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.