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Biomedical subjects

O Kandler

Publications and source records attributed to O Kandler.

At least 37 records · Page 2Linked to original sources
PubMed1981

Amino acid sequence of a dodecapeptide from the substrate-binding region of the L-lactate dehydrogenase from Lactobacillus curvatus, Lactobacillus xylosus and Bacillus stearothermophilus.

The amino acid sequence of dodecapeptides from the substrate-binding region of 3 bacterial L-lactate dehydrogenases (Lactobacillus xylosus, Lactobacillus curvatus and Bacillus stearothermophilus) were determined. They show a very high homology to the sequences of the corresponding known animal enzymes. There is, however, an essential difference between the sequences of pro- and eucaryotic enzymes: the Asn residue in position 166, common to all eucaryotes, is replaced by serine in lactobacilli and by isoleucine in Bacillus stearothermophilus. The cysteine residue in position 165, formerly considered as essential, seems to be restricted to the vertebrates, while all so far investigated invertebrates and bacteria have threonine at this position.

Amino Acid Sequence↗
PubMed1980

Factors affecting the quaternary structure of the allosteric L-lactate dehydrogenase from Lactobacillus casei and Lactobacillus curvatus as investigated by hybridization and ultracentrifugation.

The allosteric L-lactate dehydrogenases of Lactobacillus curvatus and Lactobacillus casei exist in the tetrameric from (molecular weight about 145 000) at pH 5.0--5.5 even in the absence of the effectors Mn2+ and Fru(1,6)P2 (fructose 1,6-bisphosphate), but undergo reversible dissociation to monomers (molecular weight about 35 000) at higher pH values or in the presence of urea. In the range between pH 5.5 (tetrameric state) and pH 7.4 (monomeric state) the L. curvatus L-lactate dehydrogenase exists in a dissociation-association equilibrium comprising tetramers, dimers and monomers as indicated by the Sc20,w values and the results of hybridization experiments. The simultaneous addition of both effectors [Mn2+ and Fru(1,6)P2] at pH 7.4, however, resulted in the stabilization of the tetrameric form. The addition of Fru(1,6)P2 alone at pH 7.4 had almost no influence on the quarternary structure, whereas the addition of Mn2+, as well as that of NADH, largely prevented dissociation. The L-lactate dehydrogenase of L. casei showed similar properties, although the enzyme dissociates only at about pH greater than or equal to 7.8. As in the case of the L. curvatus enzyme, Fru(1,6)P2 has no influence on the pH-dependent dissociation of the L. casei enzyme, whereas Mn2+ stabilizes the tetrameric structure. Reconstitution of a mixture of the two dissociated enzymes results in the formation of all statistically possible, enzymatically active hybrids. No hybridization between the allosteric enzymes from L. casei and L. curvatus and the non-allosteric ones of Lactobacillus plantarum and Lactobacillus acidophilus was observed.

Allosteric Regulation↗
PubMed1979

The amino acid sequence of the peptide moiety of the pseudomurein from Methanobacterium thermoautotrophicum.

The amino acid sequence of the peptide subunits of the peptide moiety of the sacculus polymer (pseudomurein) of Methanobacterium thermoautotrophicum was elucidated by analysing overlapping peptides obtained from partial acid hydrolsates of isolated sacculi. It is suggested that the peptide subunits are attached to glycan strands via one of their glutamyl residues. Another glutamyl residue may crosslink two adjacent peptide subunits to form a dimer. The calculated molar ratios of the amino acids and the percentages of the N- or C-terminal amino acid residues of the supposed dimers are compatible with those actually found in the sacculus polymer.

Amino Acid Sequence↗
PubMed1978

Chemical composition of the peptidoglycan-free cell walls of methanogenic bacteria.

Cell walls were prepared from freeze-dried samples of 7 strains of Methanobacterium by mechanical disintegration of the cells followed by incubation with trypsin. Electron microscopy revealed the presence of sacculi exhibiting the shape of the original cells, on which no surface structure could be detected. Ultrathin sections of the isolated sacculi showed a homogenously electron dense layer of about 10--15 nm in width. The ash content varied between 8 and 18% of dry weight. The sacculi of all the strains contained Lys: Ala:Glu:GlcNAc or GalNAc in a molar ratio of about 1:1.2:2:1. In one strain (M. ruminantium M1) alanine is replaced by threonine, however, Neutral sugars and--in some strains--additional amounts of the amino sugars were present in variable amounts, and could be removed by formamide extraction or HF treatment without destroying the sacculi. No muramic acid or D-amino acids typical of peptidoglycan were found. Therefore, the sacculi of the methanobacteria consist of a different polymer containing a set of three L-amino acids and one N-acetylated amino sugar. From cells of Methanospirillum hungatii no sacculi, but tube-like sheaths could be isolated, which tend to fracture perpendicularly to the long axis of the sheath along the fibrills seen on the surface. The sheaths consist of protein containing 18 amino acids and small amounts of neutral sugars. They are resistent to the proteinases tested and are not disintegrated by boiling in 2% sodium dodecylsulfate for 30 min. The three Gram-negative strains Black Sea isolate JR-1, Cariaco isolate JR-1 and Methanobacterium mobile do not contain a rigid sacculus, but merely a SDS-sensitive surface layer composed of regularly arranged protein subunits. This evidence indicates that, within the methanogens, different cell wall polymers characteristic of particular groups of organisms may have evolved during evolution, and supports the hypothesis that the evolution of the methanogens was separated from that of the peptidoglycan-containing procaryotic organisms at a very early stage.

Acetates↗
PubMed1978

[Peptidoglycan type and cell wall polysaccharide composition of Cellulomonas cartalyticum and some coryneform organisms (author's transl)].

Cellulomonas cartalyticum was found to contain a peptidoglycan type different from that of the other species of Cellulomonas. The diamino acid is lysin instead of ornithine and the interpeptide bridge consists of D-Asp-D-Ser. The same peptidoglycan type occurs in Corynebacterium manihot, Brevibacterium liticum and Arthrobacter luteus. These non cellulolytic organisms are most likely not closely related with Cellulomonas cartalyticum, as indicated by the very different G +C content of their DNA, although they formed a narrow cluster including C. cartalyticum when numeric taxonomical methods were applied.

Actinomycetales↗
PubMed1977

On the specificity of the uridine diphospho-N-acetylmuramyl-alanyl-D-glutamic acid: diamino acid ligase of Bifidobacterium globosum.

The peptidoglycan of Bifidobacterium globosum contains ornithine and lysine alternately in the same position of the peptide subunit. The uridine diphospho-N-acetylmuramyl-alanyl-D-glutamic acid: diamino acid ligase of this organism was purified 700-fold. Since the activities for the incorporation of ornithine and lysine into uridine diphospho-N-acetylmuramyl-tripeptide did not separate during purification and since the incorporation of ornithine is competitively inhibited by lysine and vice versa, both ornithine and lysine are assumed to be incorporated by one single enzyme. Studies on the specificity of the ligase toward analogs of ornithine have shown that the enzyme requires a diamino, monocarboxylic acid with 4-6 carbon atoms. Methylation of the epsilon-amino group or hydroxylation of the delta-carbon atom of lysine decreases the competitive properties of the analog, whereas the substitution of the gamma-methylen group by sulfur (S-2-aminoethyl cysteine) results in a highly competitive compound.

Actinomycetaceae↗
PubMed1977

Comparative studies of lactate dehydrogenases in lactic acid bacteria. Amino-acid composition of an active-site region and chemical properties of the L-lactate dehydrogenase of Lactobacillus casei, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus acidophilus.

The molecular weight, the amino acid composition and the N-terminal and C-terminal amino acids of two allosteric (Lactobacillus casei, L. curvatus) and two non-allosteric (L. plantarum, L. acidophilus) L-lactate dehydrogenases, purified to homogeneity by affinity chromatography, were determined. The amino acid composition of the only tryptic peptide unequivocally common to the fingerprints of the 4 enzymes is virtually identical with that of the arginine peptide, called Arg6 of the the substratebinding site of the L-lactate dehydrogenase dehydrogenase of several animals. However, the 'essential' cysteine residue 165 is replaced by threonine, as it is in the L-lactate dehydrogenase of lobster. In addition, the 4 bacterial peptides differ by one or two changes in single amino acid residues from each other as well as from those of animals. The data indicate that not only the animal L-lactate dehydrogenases, but also the allosteric and lactate dehydrogenases from bacterial sources may have evolved from a common gene.

Amino Acids↗
PubMed1977

Lack of peptidoglycan in the cell walls of Methanosarcina barkeri.

Neither muramic acid and glucosamine nor D-glutamic acid or other amino acids typical of peptidoglycan were found in cell walls of two strains of Methanosarcina barkeri. The main components are galactosamine, neutral sugars and uronic acids. Therefore, the structural component of the cell wall most likely consists of an acid heteropolysaccharide, resembling that of Halococcus morrhuae. It is, however, not sulfated.

Bacteria↗
PubMed1977

Comparative studies of lactic acid dehydrogenases in lactic acid bacteria. I. Purification and kinetics of the allosteric L-lactic acid dehydrogenase from Lactobacillus casei ssp. casei and Lactobacillus curvatus.

The stability, pH-dependence and kinetic properties of the Mn2+ and FDP-activated NAD-dependent lactic acid dehydrogenases from Lactobacillus casei ssp. casei (ATCC 393) and L. curvatus (DSM 20010) were studied after the enzymes were purified to homogeneity by affinity chromatography. Both enzymes are virtually unidirectional, catalysing efficiency only the reduction of pyruvate. They are similar with respect to the effector requirement and pH-optimum. They differ, however, in their electrophoretic mobility, heat stability, pH-dependence of the Mn2+ requirement and several kinetic properties. It is suggested that most of these differences are caused by differences of the negative charges in the vicinity of the FDP-binding site or the site responsible for the interaction of the subunits of the enzymatically active oligomeres.

Allosteric Regulation↗
PubMed1977

Determination of the isotope distribution in malate-14C with fumarase-negative lactic acid bacteria.

No fumarase activity could be found in whole cells or in cell-free crude extracts from Leuconostoc mesenteroides or Lactobacillus curvatus. The degradation of L-malate-4-14C by these organisms yielded more than 95% of the label as 14CO2. It is therefore recommended that these organisms, rather than Lactobacillus plantarum, should be used in the determination of isotope distribution in L-malate-14C, since L. plantarum exhibits a significant fumarase activity and thus randomizes malate prior to the decarboxylation of this substance by the malolactic enzyme.

Biological Assay↗
PubMed1976

[Mechanism of the variation of the acetate/lactate/ratio during glucose fermentation by bifidobacteria (author's transl)].

It is demonstrated that most strains of bifidobacteria form much more acetate and less lactic acid from glucose than is to be expected according to the breakdown of glucose via the "bifidoshunt". The analysis of isotope distribution among the fermentation products of glucose labeled in different positions showed that the excess of acetate is the result of the phosphoroclastic splitting of a part of the pyruvate arising from carbons 4, 5, and 6 of glucose. In addition to acetate (carbons 5 and 6), formate is formed from carbon 4 and some acetate is reduced to ethanol. The formation of "extra" acetate occurs mainly during the log phase and is less pronounced in resting cells. The extent of the phosphoroclastic splitting of pyruvate varies considerably among different strains even among those from the same species.

Acetates↗
PubMed1976

Biosynthesis of peptidoglycan in Gaffkya homari. The incorporation of peptidoglycan into the cell wall and the direction of transpeptidation.

Wall membrane enzyme preparations from Gaffkya homari catalyze the formation of peptidoglycan from the precursor pairs: UDP-N-acetylglucosamine + UDP-N-acetylmuramyl-pentapeptide (UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla) and also from UDP-N-acetylglucosamine + UDP-N-acetylmuramyl-tetrapeptide (UDP-MurNAc-Ala-DGlu-Lys-DAla). Part of the reaction products is soluble in 2% sodium dodecylsfulfate whereas the other part is bound to pre-existing cell wall peptidoglycan. The incorporation into cell wall takes place by a transpeptidation reaction in which the D-alanyl-D-alanine sequences in the pre-existing cell wall function as donors and the epsilon-amino groups of the lysine residues in the newly synthesized peptidoglycan strands function as acceptors. Nepsilon-D-Alanyl-lysine linkages are formed. At saturating concentration of UDP-N-acetylglucosamine, the enzyme system exhibits similar apparent Km values (30--80 muM) for UDP-MurNAc-pentapeptide and UDP-MurNAc-tetrapeptide both for the formation of cell-wall bound peptidoglycan and total (i.e. soluble + cell-wall-bound) peptidoglycan. The V values are also in the same order of magnitude (270-650 pmol x min-1 x mg of protein -1). However, UDP-MurNAc-tetrapeptide was a slightly better substrate than UDP-MurNAc-pentapeptide for the formation of cell-wall-bound peptidoglucan. The synthesis of total and cell-wall-bound peptidoglycan from UDP-MurNAc-pentapeptide was competitively inhibited by UDP-MurNAc-tetrapeptide and vice versa. UDP-MurNAc-tripeptide and both UDP-Mur-NAc-pentapeptide and UDP-Mur-NAc-tetrapeptide in which the epsilon-amino group of the lysine residue was substituted by an acetyl group were utilized less efficiently than UDP-MurNAc-pentapeptide and UDP-MurNAc-tetrapeptide for the formation of soluble peptidoglycan; they were exceedingly poor substrates for the formation of cell-wall-bound peptidoglycan.

Acyltransferases↗
PubMed1976

[Mode of action of D-amino acids on the biosynthesis of peptidoglycan (author's transl)].

The mechanism of growth inhibition by D-amino acids was studied. D-Serine at concentrations from 0.02-0.2 M was sufficient to cause partial growth inhibition in seven species of bacteria representing the four most common types of peptidoglycan. The inhibited cells displayed morphological alterations. In the nucleotide-activated peptidoglycan precursors of these cells, D-alanine residues in position 4 and/or 5 of the peptide moiety were partially or even completely replaced by D-serine. The peptidoglycan also contained D-serine instead of D-alanine, but the percentual content of D-serine was significantly lower than that in the precursors. In addition, the modified peptidoglycan was less cross-linked than the normal one. Four other D-amino acids (D-threonine, D-valine, D-leucine, D-methionine) at concentrations of about 0.2 M caused similar effects as did D-serine when applied to Corynebacterium callunae and Bacillus subtilis. Thus the mode of action of D-amino acids on peptidoglycan synthesis can be generally described as follows: in their presence, at growth inhibiting concentrations modified nucleotide-activated peptidoglycan precursors are formed in which D-alanine residues are replaced by the D-amino acids. They are less efficiently incorporated into peptidoglycan. A high percentage of the modified muropeptides remains non-cross-linked, since they are poor substrates for the transpeptidation reaction. In the majority of the organisms, cross-linking was decreased when D-alanine in position 4 of the peptide subunit was replaced, in two organisms (Corynebacterium insidiosum and Staphylococcus aureus) replacement in position 5 was most effective, however. The low extent of cross-linkage is consistent with the morphological aberrations of inhibited cells. In previous studies with glycine, results were described that were in close analogy to those obtained with D-amino acids. However, glycine can replace not only D-alanine residues in position 4 and 5 but also L-alanine in position 1 of the peptide subunit.

Alanine↗
PubMed1974

Biosynthesis of Umbelliferose in Aegopodium podagraria.

The following reaction leading to the synthesis of the trisaccharide umbelliferose was demonstrated in an enzyme preparation from leaves of Aegopodium podagraria L.: sucrose + UDP-gal-(14)C --> umbelliferose-(14)C + UDP. Neither galactinol nor galactose 1-phosphate could replace UDP-gal. Among 10 different sugars tested only sucrose was a suitable galatosyl acceptor.

Journal Article↗
PubMed1974

Properties of glucosyltransferase and glucan transferase from spinach.

A glucosyl and a glucosyl-glucan transferase activity from spinach (Spinacia oleracea L. var. Matador) leaves have been partially purified and characterized. The latter activity (fraction 1 after diethylaminoethylcellulose chromatography) is responsible for the transfer of glucosyl as well as of maltosyl, maltotriosyl, and higher homologous residues to glucose giving rise to maltose and the correspondingly larger molecules. This fraction also shows beta-amylase activity. The transfer takes place only to glucose; maltose, as well as other alpha-1,4-glucans, serve as donors. The enzyme fraction 2 is amylase-free and catalyzes only the transfer of glucosyl moieties, again with high acceptor specificity to glucose. Maltose and larger alpha-1, 4-glucans, with the exception of maltotriose and maltotetraose, act as donors. The physiological function of these enzymes may be the formation of oligosaccharide primers for starch synthetase or phosphorylase.

Journal Article↗