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PubMed1991

Heparinase II from Flavobacterium heparinum. HPLC analysis of the saccharides generated from chemically modified heparins.

Saccharides produced by the action of heparinase II on native pig mucosal heparin (heparin IS), de-N-sulphated heparin (heparin IH), N-acetylheparin (heparin IA), de-N/O-sulphated heparin (heparin IVH), de-O-sulphated heparin (heparin IVS) and de-O-sulphated N-acetylheparin (heparin IVA) were analysed by reversed-phase HPLC using Spherisorb ODS2. Fractions obtained by gel filtration with Bio-Gel P-4 were similarly examined. Heparin IS gave delta UA-2S----GlcNS-6S (IS) as the major unsaturated disaccharide and lesser amounts of delta UA----GlcNS-6S (IIS), delta UA-2S----GlcNS (IIIS), delta UA----GlcNS (IVS), delta UA-2S----GlcNAc-6S (IA), delta UA----GlcNAc-6S (IIA), delta UA-2S----GlcNAc (IIIA) and delta UA----GlcNAc (IVA). Heparins IA, IVA and IVS gave as the predominant unsaturated disaccharide that corresponding to the major repeat structure of the polymer. These were respectively delta UA-2S----GlcNAc-6S (IA), delta UA-GlcNAc (IVA) and delta UA----GlcNS (IVS). Minor disaccharides from the heterogeneous structure in native pig heparin and from residual O-sulphates after the de-O-sulphating process were detected. Heparin IH was degraded more slowly than any of the N-substituted heparins. The predominant unsaturated disaccharide was IH, which was derived from the major repeating unit. In addition, disaccharides IIH, IIIH, IA, IIA and IVA were detected. Heparin IVH showed little degradation, the unsaturated disaccharide IVH not being detected after 24 h. Disaccharide IVA was obtained from the heterogeneous sequence in heparin IVH. Several higher oligosaccharides were identified in the gel-filtration fractions including saccharides from the linkage region (for heparin IS and IVA) and the anti-thrombin binding site (for heparin IS only). A tetrasaccharide and hexasaccharide, with the structures delta UA----GlcNAc----UA----GlcNAc and delta UA----GlcNAc----UA----GlcNAc----UA----GlcNAc, were present in the HPLC profiles of heparins IA and IVA.

Animals↗
PubMed2000

Genetic-biochemical analysis and distribution of the Ambler class A beta-lactamase CME-2, responsible for extended-spectrum cephalosporin resistance in Chryseobacterium (Flavobacterium) meningosepticum.

In vitro synergy between extended-spectrum cephalosporins and either clavulanic acid or cefoxitin was found for Chryseobacterium meningosepticum isolates during a double-disk assay on an agar plate. An extended-spectrum beta-lactamase (ESBL) gene from a C. meningosepticum clinical isolate was cloned and expressed in Escherichia coli DH10B. Its protein conferred resistance to most beta-lactams including extended-spectrum cephalosporins but not to cephamycins or to imipenem. Its activity was strongly inhibited by clavulanic acid, sulbactam, and tazobactam, as well as by cephamycins and imipenem. Sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) of 891 bp with a G+C content of 33.9%, which lies close to the expected range of G+C contents of members of the Chryseobacterium genus. The ORF encoded a precursor protein of 297 amino acids, giving a mature protein with a molecular mass of 31 kDa and a pI value of 9.2 in E. coli. This gene was very likely chromosomally located. Amino acid sequence comparison showed that this beta-lactamase, named CME-2 (C. meningosepticum ESBL), is a novel ESBL of the Ambler class A group (Bush functional group 2be), being weakly related to other class A beta-lactamases. It shares only 39 and 35% identities with the ESBLs VEB-1 from E. coli MG-1 and CBL-A from Bacteroides uniformis, respectively. The distribution of bla(CME-2) among unrelated C. meningosepticum species isolates showed that bla(CME-2)-like genes were found in the C. meningosepticum strains studied but were absent from strains of other C. meningosepticum-related species. Each C. meningosepticum strain produced at least two beta-lactamases, with one of them being a noninducible serine ESBL with variable pIs ranging from 7.0 to 8.5.

Amino Acid Sequence↗
PubMed2000

Genetic diversity of carbapenem-hydrolyzing metallo-beta-lactamases from Chryseobacterium (Flavobacterium) indologenes.

The class B carbapenem-hydrolyzing beta-lactamase IND-1 has been characterized for Chryseobacterium indologenes strain 001. With internal primers for the bla gene for IND-1 (bla(IND-1)) and an internal bla(IND-1) probe, PCR amplifications failed, while hybridization results were positive when DNA from another C. indologenes isolate, strain CIP101026, was used as a template. Thus, a bla(IND)-related gene was cloned from this C. indologenes reference strain. Sequencing of the insert of a recombinant plasmid conferring resistance to carbapenems revealed an open reading frame with a G + C content of 39.9% and coding for a 243-amino-acid preprotein named IND-2. IND-2 shared 80% amino acid identity with IND-1 and had a similar broad-spectrum resistance profile, including resistance to carbapenems. It was classified in functional subgroup 3a of class B carbapenem-hydrolyzing beta-lactamases. IND-1 and IND-2, despite their genetic diversity, possessed similar kinetic parameters, except that ceftazidime was hydrolyzed less by IND-2. To obtain the entire bla(IND)-related gene sequences of eight other C. indologenes isolates, PCR was performed using internal and external primers, followed by inverse PCR techniques. The likely chromosome-mediated metallo-beta-lactamases of the 10 C. indologenes isolates were divided into several groups and subgroups. IND-1, IND-2, IND-2a, IND-3, and IND-4 shared 77 to 99% amino acid identity.

Amino Acid Sequence↗
PubMed1993

Nylon oligomer degradation gene, nylC, on plasmid pOAD2 from a Flavobacterium strain encodes endo-type 6-aminohexanoate oligomer hydrolase: purification and characterization of the nylC gene product.

A new type of nylon oligomer degradation enzyme (EIII) was purified from an Escherichia coli clone harboring the EIII gene (nylC). This enzyme hydrolyzed the linear trimer, tetramer, and pentamer of 6-aminohexanoate by an endo-type reaction, and this specificity is different from that of the EI (nylA gene product) and EII (nylB gene product). Amino acid sequencing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified EIII demonstrated that the enzyme is made of two polypeptide chains arising from an internal cleavage between amino acid residues 266 and 267.

Amidohydrolases↗
PubMed1991

Purification and properties of pentachlorophenol hydroxylase, a flavoprotein from Flavobacterium sp. strain ATCC 39723.

A pentachlorophenol (PCP) hydroxylase which catalyzed the conversion of PCP to 2,3,5,6-tetrachlorohydroquinone and released iodide from triiodophenol in the presence of NADPH and oxygen was identified. The enzyme was purified by protamine sulfate precipitation, ammonium sulfate precipitation, hydrophobic chromatography, anion-exchange chromatography, gel filtration chromatography, and crystallization. The enzyme was a monomer with a molecular weight of 63,000. Under certain conditions, dimer and multimer conformations were also observed. The pI of the enzyme was pH 4.3. The optimal conditions for activity were a pH of 7.5 to 8.5 and a temperature of 40 degrees C. Each enzyme molecule contained one flavin adenine dinucleotide molecule. The Km for PCP was 30 microM and the Vmax was 16 mumol/min/mg of protein. The enzymatic reaction required 2 mol of NADPH per mol of halogenated substrate. On the basis of the data we present, it is likely that PCP hydroxylase is a flavoprotein monooxygenase. The addition of flavins to the reaction mixture did not stimulate the enzymatic reaction; however, we identified the photodegradation of triiodophenol and tribromophenol, but not PCP, by flavin mononucleotide or riboflavin and light.

Chromatography, Affinity↗