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PubMed1976

Flavobacterium endophthalmitis following keratoplasty. Use of a tissue culture medium-stored cornea.

This case of Falvobacterium meningosepticum endophthalmitis in the immediate postoperative period following a penetrating keratoplasty represents the first known isolation of F meningosepticum from the eye and, also, our first encounter with bacterial endophthalmitis following keratoplasty. This case occurred soon after conversion from whole eye moist chamber storage to tissue culture storage (McCarey-Kaufman medium). This storage technique may predispose to development of postoperative endophthalmitis. We offer suggestions to minimize the possibility of such infection.

Aged↗
PubMed1993

Substrate specificity of the heparin lyases from Flavobacterium heparinum.

A detailed knowledge about the substrate specificities of the heparin lyases is necessary when using these enzymes as tools for elucidating the sequence of heparin and heparan sulfate. The substrate specificity of heparin lyases I, II, and III have been profiled with structurally defined, heparin-derived oligosaccharides. The primary substrate specificities of heparin lyases I and III require the presence of 2-O-sulfated alpha-L-idopyranosyluronic acid and beta-D-glucopyranosyluronic acid residues, respectively, at the linkages being cleaved. Heparin lyase II demonstrates an intriguingly broad primary specificity for oligosaccharides, acting at linkages containing alpha-L-idopyranosyluronic and beta-D-glucopyranosyluronic acid as well as at linkages containing alpha-L-galactopyranosyluronic acid residues. In addition to their primary specificities, each lyase also demonstrates secondary specificities under forcing conditions. Differences in the sulfation pattern within uronic acid residues and sulfation of adjacent residues has profound impact on the ease of lyase cleavage of a glycosidic linkage. Specifically, heparin lyases I and III exhibit secondary specificity for oligosaccharides containing an unsulfated alpha-L-idopyranosyluronic acid residue. The lack of sulfation on residues adjacent to the linkage undergoing cleavage increases the action of heparin lyase III on a glycosidic linkage. In contrast, reduced sulfation on adjacent residues make glycosidic linkage resistant to heparin lyase I. The primary and secondary specificity can be rationalized on the basis of most favorable solution conformation of the uronic acid residues.

Carbohydrate Conformation↗
PubMed1996

A comparative analysis of the primary sequences and characteristics of heparinases I, II, and III from Flavobacterium heparinum.

Heparinases I, II and III from F. heparinum cleave heparin-like molecules, with a high degree of substrate specificity, at the glucosamine-uronate linkage by elimination, leaving an unsaturated C4-C5 bond in the uronic acid. The primary sequences of these enzymes have been reported earlier. In this study we perform a comparative analysis of the properties and primary sequences of heparinase I, II and III. Alignment of the primary sequences revealed little sequence homology (15% residue identity in a LALIGN alignment) at both DNA and amino acid levels. There are three basic clusters in heparinase II satisfying the heparin binding consensus sequence with one of the sequences sharing homology with a consensus sequence in the heparin binding site of heparinase I and two basic clusters in heparinase III. Similar to heparinase I, there are two putative 'EF-hand' calcium coordinating motifs in heparinase III, while heparinase II does not contain any such motifs. Recombinant heparinases II and III's degradation of the substrate and the subsequent separation of the oligosaccharide products by POROS anion exchange chromatography were identical to those obtained from native heparinases II and III from F. heparinum.

Chromatography, High Pressure Liquid↗
PubMed1995

Enzymatic peptide synthesis by the recombinant proline-specific endopeptidase from Flavobacterium meningosepticum and its mutationally altered Cys-556 variant.

Proline-specific endopeptidase (PSE) (EC 3.4.21.26) was investigated for its potential as a catalyst in peptide synthesis. Using an activated peptide ester or a peptide amide as the acyl component, the enzyme catalyzed kinetically controlled aminolysis and transpeptidation respectively, with various amino acid amides as acyl acceptors. To a certain extent the nucleophile preference reflected the amino acid preference in the S1'-position of the enzyme in peptide hydrolysis: the highest fractions of aminolysis were obtained using amino acid amides with hydrophobic side-chains (e.g. Leu-NH2, Phe-NH2). PSE also catalyzed the thermodynamically controlled condensation of short peptides with a free carboxyterminus and various amino acid amides. This enabled us to examine the acceptance of different acyl components in the substrate-binding site of the enzyme with regard to their amino acid composition: In the S1 position proline was clearly favored, but alanine was also accepted, whereas the S2 subsite accepted various amino acids rather unspecifically. Since PSE was shown to be extremely sensitive against water-miscible organic solvents, an alternative approach was used to increase yields in enzymatic peptide synthesis: a derivative of PSE in which the catalytic Ser-556 is converted to a Cys was constructed by protein engineering. This mutant (PSEcys) exhibited a dramatically increased peptide ligase activity in aqueous solution.

Amino Acid Sequence↗