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F C Neuhaus

Publications and source records attributed to F C Neuhaus.

At least 19 recordsLinked to original sources
PubMed1992

D-alanyl-lipoteichoic acid in Lactobacillus casei: secretion of vesicles in response to benzylpenicillin.

Vesicles containing lipoteichoic acid (LTA) have been isolated from Lactobacillus casei ATCC 7469 grown in the presence of either benzylpenicillin or D-cycloserine. These cell wall antibiotics enhanced the rate of LTA and lipid secretion 6.7 times, whereas chloramphenicol inhibited their release. The formation of these vesicles from peripheral and septal wall regions did not appear to be the result of bacteriolysis. The vesicle composition of LTA and lipid was similar to that of the cytoplasmic membrane whereas the protein composition was dissimilar. The size of these vesicles ranged from 20 to 40 nm and the length of LTA ranged from 5 to 50 glycerol phosphate residues. The isolation of these vesicles provides a potential in vitro acceptor system for studying the D-alanylation of lipoteichoic acid.

Chloramphenicol↗
PubMed1992

Biosynthesis of D-alanyl-lipoteichoic acid: cloning, nucleotide sequence, and expression of the Lactobacillus casei gene for the D-alanine-activating enzyme.

The D-alanine-activating enzyme (Dae; EC 6.3.2.4) encoded by the dae gene from Lactobacillus casei ATCC 7469 is a cytosolic protein essential for the formation of the D-alanyl esters of membrane-bound lipoteichoic acid. The gene has been cloned, sequenced, and expressed in Escherichia coli, an organism which does not possess Dae activity. The open reading frame is 1,518 nucleotides and codes for a protein of 55.867 kDa, a value in agreement with the 56 kDa obtained by electrophoresis. A putative promoter and ribosome-binding site immediately precede the dae gene. A second open reading frame contiguous with the dae gene has also been partially sequenced. The organization of these genetic elements suggests that more than one enzyme necessary for the biosynthesis of D-alanyl-lipoteichoic acid may be present in this operon. Analysis of the amino acid sequence deduced from the dae gene identified three regions with significant homology to proteins in the following groups of ATP-utilizing enzymes: (i) the acid-thiol ligases, (ii) the activating enzymes for the biosynthesis of enterobactin, and (iii) the synthetases for tyrocidine, gramicidin S, and penicillin. From these comparisons, a common motif (GXXGXPK) has been identified that is conserved in the 19 protein domains analyzed. This motif may represent the phosphate-binding loop of an ATP-binding site for this class of enzymes. A DNA fragment (1,568 nucleotides) containing the dae gene and its putative ribosome-binding site has been subcloned and expressed in E. coli. Approximately 0.5% of the total cell protein is active Dae, whereas 21% is in the form of inclusion bodies. The isolation of this minimal fragment without a native promoter sequence provides the basis for designing a genetic system for modulating the D-alanine ester content of lipoteichoic acid.

Amino Acid Sequence↗
PubMed1991

Biosynthesis of peptidoglycan in Gaffkya homari: on the target(s) of benzylpenicillin.

The formation of acceptor for the N epsilon-(D-Ala)-acceptor transpeptidase is an essential feature of nascent peptidoglycan processing. In Gaffkya homari the synthesis of cross-bridges in peptidoglycan includes a variety of penicillin-sensitive enzymes, e.g., transpeptidase, DD-carboxypeptidase, and LD-carboxypeptidase. To determine the primary target, we grew cultures in the presence of the MICs of benzylpenicillin (0.2 microgram/ml), methicillin (10 micrograms/ml), cephalothin (5 micrograms/ml), and cefoxitin (25 micrograms/ml) and examined the monomer-dimer composition of each peptidoglycan by high-performance liquid chromatography after muramidase digestion. From these studies it was recognized that of all the dimers, the synthesis of the predominant cross-bridge, diamidated octapeptide (-Ala-iso-D-Gln-Lys-D-Ala -Ala-iso-D-Gln-Lys-D-Ala), is most sensitive to the action of the beta-lactam at its MIC. The enhanced deamidation of the acceptor tetrapeptide, one of the substrates for the transpeptidase, is correlated with the inhibition of this cross-bridge. For example, at the MIC of benzylpenicillin, the ratio of amidated tetrapeptide to nonamidated tetrapeptide decreased from 2.8 in the control to 1.0 in the treated culture. From these results it would appear that a decrease in preferred acceptor for the transpeptidase results in the inhibition of synthesis of this major cross-bridge. Thus, the metabolism of the amide function of the monomer peptides may represent an additional feature of processing in the assembly of cross-bridged dimers in the peptidoglycan of this organism that is sensitive to the action of beta-lactam.

Chromatography, High Pressure Liquid↗
PubMed1987

Intramembranal events in the biosynthesis of peptidoglycan in Gaffkya homari.

In order to monitor the intermediates involved in nascent peptidoglycan (PG) assembly in Gaffkya homari, a pulse/chase assay utilizing UDP-MurNAc-Ala-DGlu-Lys(N epsilon-Dns)-DAla-DAla [Dns (dansyl) = 5-(dimethylamino)naphthalene-1-sulfonyl] was devised. The perturbation introduced by the dansyl group provided a means for separating the synthesis of nascent PG into discrete stages. Together with paramagnetic quenching of the fluorophore by n-doxylstearic acids (n = 5, 7, 12, 16; doxyl = N-oxy-4',4'-dimethyloxazolidine), this assay allows one to observe the synthesis of undecaprenyl diphosphate-MurNAc-[N epsilon-Dns)pentapeptide)-GlcNAc and its utilization for the formation of dansyl-labeled PG by fluorescence emission and by change in specific positional quenching. The utilization of the dansylated lipid disaccharide-pentapeptide occurs without a lag, whereas the formation of the chromatographically immobile dansylated PG occurs with a lag of 4-6 min. Membrane-associated undecaprenyl diphosphate-MurNAc-(N epsilon-Dns)-pentapeptide was quenched primarily by 7-doxylstearate. In contrast, the fluorophore of the undecaprenyl diphosphate-MurNAc-[N epsilon-Dns)pentapeptide)-GlcNAc was quenched primarily by 5-doxyl- and 16-doxylstearates. In the chase phase of the assay, quenching by 16-doxylstearate decreased at a faster rate than that by 5-doxylstearate during the formation of dansyl-labeled PG.

Carbon Radioisotopes↗
PubMed1987

Assembly of D-alanyl-lipoteichoic acid in Lactobacillus casei: mutants deficient in the D-alanyl ester content of this amphiphile.

D-Alanyl-lipoteichoic acid (D-alanyl-LTA) from Lactobacillus casei ATCC 7469 contains a poly(glycerophosphate) moiety that is acylated with D-alanyl ester residues. The physiological function of these residues is not well understood. Five mutant strains of this organism that are deficient in the esters of this amphiphile were isolated and characterized. When compared with the parent, strains AN-1 and AN-4 incorporated less than 10% of D-[14C]alanine into LTA, whereas AN-2, AN-3, and AN-5 incorporated 50%. The synthesis of D-[14C]alanyl-lipophilic LTA was virtually absent in the first group and was approximately 30% in the second group. The mutant strains synthesized and selected the glycolipid anchor for LTA assembly. In addition, all of the strains synthesized the poly(glycerophosphate) moiety of LTA to the same extent as did the parent or to a greater extent. It was concluded that the membranes from the mutant strains AN-1 and AN-4 are defective for D-alanylation of LTA even though acceptor LTA is present. Mutant strains AN-2 and AN-3 appear to be partially deficient in the amount of the D-alanine-activating enzyme. Aberrant morphology and defective cell separation appear to result from this deficiency in D-alanyl ester content.

Alanine↗
PubMed1986

In vivo target of benzylpenicillin in Gaffkya homari.

It has been established that the DD-carboxypeptidase is the primary in vitro target of benzylpenicillin in Gaffkya homari (W. P. Hammes, Eur. J. Biochem. 70:107-113, 1976). To determine whether this enzyme is also the primary target of benzylpenicillin in vivo, we compared the effects of this beta-lactam, cefmenoxime, cephalothin, and cefoxitin on growth with their acylation of penicillin-binding protein (PBP) 9, the DD-carboxypeptidase. Results of three types of experiments with membrane-walls indicated that PBP 9 is this enzyme and that it is the primary in vitro target of these beta-lactams in the synthesis of sodium dodecyl sulfate (SDS)-insoluble peptidoglycan. First, the acylation of PBP 9 by these beta-lactams paralleled the inhibition of DD-carboxypeptidase and the inhibition of SDS-insoluble peptidoglycan synthesis. Second, the rate of benzylpenicillin release from PBP 9 correlated with the recovery of DD-carboxypeptidase. Third, DD-carboxypeptidase activity was detected in a protein with the same apparent molecular weight as PBP 9 after elution from an SDS-polyacrylamide gel. When intact cells were treated with benzylpenicillin, the minimum growth inhibitory concentration (MGIC) correlated with the concentration of [35S]benzylpenicillin required to acylate PBPs 6 and 9 by 50%. When intact cells were treated with cefmenoxime, cephalothin, or cefoxitin, the MGICs correlated with the concentration of unlabeled beta-lactam required to reduce the subsequent binding of [35S]benzylpenicillin by 50% (ED50) for PBP 6. In contrast, the MGICs of these beta-lactams did not correlate with the ED50s for PBP 9. PBP 9 was not acylated by cefmenoxime or cephalothin at their MGICs, whereas this PBP was fully acylated by cefoxitin at one-tenth of its MGIC. It is suggested that PBP 6 may be a primary target of growth inhibition by benzylpenicillin, cefmenoxime, cephalothin, and cefoxitin; PBP 9, the DD-carboxypeptidase, is dispensable for growth under laboratory conditions; and PBP 9 does not appear to be a primary in vivo target of these beta-lactams, even though this PBP is their primary target in vitro.

Bacterial Proteins↗
PubMed1985

Biosynthesis of D-alanyl-lipoteichoic acid by Lactobacillus casei: interchain transacylation of D-alanyl ester residues.

Lipoteichoic acid (LTA) from Lactobacillus casei contains poly(glycerophosphate) substituted with D-alanyl ester residues. The distribution of these residues in the in vitro-synthesized polymer is uniform. Esterification of LTA with D-alanine may occur in one of two modes: (i) addition at random or (ii) addition at a defined locus in the poly(glycerophosphate) chain followed by redistribution of the ester residues. A time-dependent transacylation of these residues from D-[14C]alanyl-lipophilic LTA to hydrophilic acceptor was observed. The hydrophilic acceptor was characterized as D-alanyl-hydrophilic LTA. This transacylation requires neither ATP nor the D-alanine incorporation system, i.e., the D-alanine activating enzyme and D-alanine:membrane acceptor ligase. No evidence for an enzyme-catalyzed transacylation reaction was observed. We propose that this process of transacylation may be responsible for the redistribution of D-alanyl residues after esterification to the poly(glycerophosphate). As a result, it is difficult to distinguish between these proposed modes of addition.

Acylation↗
PubMed1983

Biosynthesis of D-alanyl-lipoteichoic acid: role of diglyceride kinase in the synthesis of phosphatidylglycerol for chain elongation.

Lipophilic and hydrophilic D-alanyl-lipoteichoic acids are elongated in Lactobacillus casei by the transfer of sn-glycerol 1-phosphate units from phosphatidylglycerol to the poly(glycerophosphate) moiety of the polymer. These sn-glycerol 1-phosphate units are added to the end of the poly(glycerophosphate) which is distal to the glycolipid anchor; 1,2-diglyceride results from this addition. The presence of a diglyceride kinase was suggested by the ATP-dependent phosphorylation of 1,2-diglyceride to phosphatidic acid. Inorganic phosphate was used to initiate the synthesis of lipophilic lipoteichoic acid (LTA) and the elongation of both lipophilic and hydrophilic LTA. Three observations suggest that phosphate and other anions play a role in the in vitro synthesis of LTA and its precursors. First, the conversion of 1,2-diglyceride to phosphatidic acid by diglyceride kinase was stimulated. Second, the synthesis of phosphatidylglycerol was increased. Third, the elongation of lipophilic and hydrophilic LTA was enhanced. These observations indicated that one effect of phosphate might be to enhance the utilization of 1,2-diglyceride for the synthesis of phosphatidic acid. This phospholipid is a precursor of phosphatidylglycerol, the donor of sn-glycerol 1-phosphate for elongation of LTA.

Adenosine Triphosphate↗
PubMed1980

Initial membrane reaction in peptidoglycan synthesis: perturbation of lipid-phospho-N-acetylmuramyl-pentapeptide translocase interactions by n-butanol.

Phospho-N-acetylmuramyl-pentapeptide translocase, the initial membrane enzyme in the biosynthesis of peptidoglycan, requires a lipid microenvironment for function. n-Butanol was reversibly intercalated into membranes to perturb the hydrophobic interactions in this microenvironment in order to define further the role of lipid. In the concentration range for maximal stimulation of enzymic activity (0.12-0.18 M), n-butanol causes a 40% decrease in the fluorescence emission of the dansylated product, undecaprenyl diphosphate-(N epsilon-dansyl)pentapeptide. Since no change in emission maximum occurs below 22 degrees C in the presence of 0.12 M n-butanol, it is concluded that intercalation of this alkanol causes an increase in fluidity. Above 22 degrees C this concentration of n-butanol causes both a decrease in the fluorescence emission and a red shift in the emission maximum. It is concluded that a polarity change as well as fluidity change occurs above 22 degrees C. n-Butanol also causes a significant change in the phase transition experienced by the dansylated lipid product. Thus, it is possible with n-alkanols, e.g. n-butanol, to perturb lipid-translocase interactions resulting in an increase in fluidity in the microenvironment of the enzyme. This change in fluidity correlates with a stimulation of enzymic activity.

1-Butanol↗
PubMed1979

Initial membrane reaction in peptidoglycan synthesis. Interaction of lipid with phospho-N-acetylmuramyl-pentapeptide translocase.

The initial membrane reaction in the biosynthesis of peptidoglycan is catalyzed by phospho-N-acetylmuramyl (MurN Ac)-pentapeptide translocase (UDP-MurNAc-Ala-gamma DGlu-Lys-DAla-DAla undecaprenyl phosphate phospho-MurNAc-pentapeptide transferase). In addition to the transfer reaction, the enzyme catalyzes the exchange of [3H]uridine monophosphate with the uridine monophosphate moiety of UDP-MurN Ac-pentapeptide. Two distinct discontinuities are observed in the slopes of the Arrhenius plots of the exchange and transfer activities at 22 and 30 degrees C for the enzyme from Staphylococcus aureus Copenhagen. Anisotropy measurements of perylene fluorescence and electron spin resonance measurements of N-oxyl-4',4'-dimethyloxazolidine derivatives of 12- and 16-ketostearic acid intercalated into membranes from this organism define the lower (T1 = 16--22 degrees C) and upper (Th = 30 degrees C) boundaries of a phase transition. These values correlate with the discontinuities observed for the activity measurements. Thus, it is proposed that the physical state of the lipid micro-environment of phospho-MurNAc-penetapeptide translocase has a significant effect on the catalytic activity of this enzyme.

Cell Membrane↗
PubMed1977

Fluorescent substrate for nascent peptidoglycan synthesis. Uridine diphosphate-N-acetylmuramyl-(Nepsilon-5-dimethylaminonaphthalene-1-sulfonyl)pentapeptide.

The synthesis of UDP-MurNAc-Ala-DGlu-Lys[Nepsilon-dimethylaminonaphthalene sulfonyl (Dns)]-DAla-DAla provides a method for the specific introduction of a fluorescent reporter group into the membrane environment of nascent peptidoglycan synthesis. To assess the degree of perturbation of this environment caused by the introduction of the dansyl substituent, this nucleotide was compared with UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla in the reaction catalyzed by phospho-MurNAc-pentapeptide translocase (UDP-MurNAc-Ala-gammaDGlu-Lys-DAla-DAla:undecaprenyl phosphate phospho-MurNA-C-pentapeptide transferase) and in the membrane-associated synthesis of nascent peptidoglycan. Phospho-MurNAc-pentapeptide translocase in membrane fragments from Staphylococcus aureus Copenhagen catalyzed the transfer of phospho-MurNAc-Ala-DGlu-Lys(Nepsilon-Dns)-DAla-DAla to undecaprenyl phosphate with a Vmax/Km of 3.8 and a Vmax of 1.6 times the values for UDP-MurNAc-pentapeptide. In the exchange reaction catalyzed by the translocase, the Rmax/Km and Rmax for the dansylated substrate were 1.8 and 0.78 times the respective values for the reference nucleotide. The equilibrium constant for the transfer reaction utilizing UDP-MurNAc-(Nepsilon-Dns)pentapeptide was 5.9 +/- 0.13 compared to 1.1 +/- 0.02 for UDP-MurNAc-pentapeptide. With respect to the proposed reaction model (Pless, D. D., and Neuhaus, F. C. (1973) J. Biol. Chem. 248, 1568-1576), the increase in Keq is consistent with a decrease in the affinity of undecaprenyl diphosphate-MurNAc-Ala-DGlu-Lys(Nepsilon-Dns)-DAla-DAla for the translocase. The fluorescence emission maximum of the phospho-MurNAc-(Nepsilon-Dns)pentapeptide moiety of UDP-MurNAc-(Nepsilon-Dns)pentapeptide was blue-shifted from 525 to 495 nm upon transfer from UMP to undecaprenyl phosphate with a 6-fold increase in quantum yield. These spectral changes provided a sensitive and continuous assay for the formation of undecaprenyl diphosphate-MurNAc-Ala-DGlu-Lys(Nepsilon-Dans)-DAla-DAla. The nascent peptidoglycan synthesizing system from Gaffkya homari utilized the dansylated nucleotide with a Vmax/Km of 0.05 and a Vmax of 0.10 times the values for UDP-MurNAc-pentapeptide. These results demonstrate that phospho-MurNAc-Ala-DGlu-Lys(Nepsilon-Dns)-DAla-DAla linked to the undecaprenyl phosphate will serve as a precursor for the synthesis of nascent peptidoglycan and that the dansyl moiety will report on the membrane environment it experiences during this synthesis.

Cell Membrane↗
PubMed1977

Biosynthesis of spin-labeled peptidoglycan: spin-spin interactions.

Membrane preparations from Gaffkya homari catalyzed the in vitro biosynthesis of soluble uncross-linked spin-labeled peptidoglycan, a uniformly labeled polynitroxide, from the spin-labeled nucleotide UDP-MurNAc-Ala-DGlu-Lys(Nepsilon-2,2,5,5-tetramethyl-1-pyrrolin-1-oxyl-3-carbonyl)-DAla-DAla (I) and UDP-GlcNAc. Soluble spin-labeled peptidoglycan was separated from membrane fragments and its spin-labeled precursor by centrifugation and gel filtration. The molecular weight distribution of the polymer was examined by agarose gel filtration. Spin-labeled [14C]peptidoglycan was polydisperse with a peak of radioactivity corresponding to a molecular weight of 5.0 X 10(5). The electron spin resonance spectrum of spin-labeled peptidoglycan was extensively broadened by spin-spin exchange interactions. These interactions were modified by changes in temperature, reduction by ascorbate, hydrolysis by lysozyme, and complexation with the antibiotic, vancomycin. Spin-spin exchange was reduced or eliminated in spin-labeled peptidoglycan by the random reduction of free radicals by ascorbate. A rotational correlation time of 0.37 ns was calculated for the probe in partially reduced spin-labeled peptidoglycan. This compares to a correlation time of 0.13 ns for the substrate (I). Raising the temperature increases spin-spin exchange line broadening. No transition points were observed for spin-labeled peptidoglycan as measured by this method. Degradati on of spin-labeled peptidoglycan by lysozyme eliminated the observed spin-spin exchange and yielded products with a mobility similar to I. Complexation of spin-labeled peptidoglycan with vancomycin resulted in both pronounced free-radical immobilization and a decrease in spin-spin exchange. The exchange effects are consistent with distance measurements in molecular models for peptidoglycan.

Binding Sites↗
PubMed1977

Growth inhibition of Escherichia coli W by D-norvalyl-D-alanine: an analogue of D-alanine in position 4 of the peptide subunit of peptidoglycan.

Position 4 analogues of d-alanine in the peptide subunit of uridine 5'-diphosphate-N-acetylmuramyl-Ala(1)-dGlu(2)- Lys(3)-dAla(4)-dAla(5) have a significant inhibitory effect on penicillin-sensitive peptidoglycan synthesis in Gaffkya homari (C. V. Carpenter, S. Goyer, and F. C. Neuhaus, 1976). The specificity profile of this in vitro system has been used as a basis for designing analogues with potential antibacterial activity. To circumvent the specificity determinants exerted by d-alanine:d-alanine ligase (adenosine 5'-diphosphate), attention was directed to dd-dipeptides of the type d-alanyl-analogue-d-alanine as a method for incorporating analogues into position 4 of the peptide subunit in vivo. Of the three dipeptides, dAbu-dAla, dNva-dAla, and dVal-dAla, only dNva-dAla (5 x 10(-4) M) inhibited the growth of Escherichia coli W in the presence of 5 x 10(-6) M d-cycloserine. This concentration of d-cycloserine did not inhibit growth, but it potentiated the bactericidal activity of the dipeptide. The lack of antibacterial activity observed with dAbu-dAla and dVal-dAla was correlated with the poor ability of these dipeptides to be taken up via the dipeptide transport system of this organism. Prevention of lysis induced by dNva-dAla plus d-cycloserine by certain dipeptides and not by others supported this correlation. It is proposed that the d-norvalyl residue of the dipeptide is incorporated in vivo into position 4 of the peptide subunit of peptidoglycan, and that this subunit is not an effective substrate in the reaction(s) catalyzed by the penicillin-susceptible enzyme(s) of cross-linked peptidoglycan synthesis.

Alanine↗
PubMed1976

Steric effects on penicillin-sensitive peptidoglycan synthesis in a membrane-wall system Gaffkya homari.

Residues 4 and 5 of the pentapeptide moiety, R-Ala1-DGlu2-Lys3-DAla4-DAla5, of peptidoglycan play an important role in the donor phase of cross-linked glycan synthesis. To assess the role of these residues in this phase, a series of UDP-MurNAc-peptides were biosynthesized with residues 4 and 5 replaced singly by either D-alpha-amino-n-butyric acid, D-norvaline, or D-valine. The six nucleotides were compared with UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla (reference) in nascent (penicillin-insensitive) peptidoglycan synthesis and in penicillin-sensitive peptidoglycan synthesis. The synthesis of penicillin-sensitive peptidoglycan is catalyzed by membrane-walls isolated from Gaffkya homari and would appear to require the concerted action of transglycosylase and transpeptidase. The membrane-wall system shows a high degree of discrimination for the steric substituents, -CH3 and -CH2CH3, in residue 4. For example, for UDP-MurNAc-Ala-DGly-Lys-DAbu-DAla and -Ala-DGlu-Lys-DAla-DAbu, Vmax/km is 0.19 and 0.95 and Vmax is 0.03 and 0.52, respectively, of the value for the reference nucleotide. In contrast, for the synthesis of nascent peptidoglycan with these nucleotides Vmax/Km is 0.75 and 0.80, and Vmax is 0.71 and 1.0, respectively, of the value for the reference nucleotide. This trend was also illustrated with the other nucleotides in the time course experiments. These results indicate that the penicillin-sensitive enzyme(s), presumably the transpeptidase, has a higher degree of specificity in the donor phase for D-alanine in residue 4 than for D-alanine in residue 5 in the cross-linking stage of peptidoglycan synthesis.

Acetylglucosamine↗
PubMed1976

Biosynthesis of peptidoglycan in Staphylococcus aureus: incorporation of the Nepsilon-Ala-Lys moiety into the peptide subunit of nascent peptidoglycan.

UDP-MurNAc-Ala-DGlu-Lys(Nepsilon-Ala)-DAla-DAla was isolated from extracts of Staphylococcus aureus Copenhagen. This nucleotide accumulated in media deficient in glycine. To establish its role in peptidoglycan biosynthesis, the nucleotide-hexapeptide was compared with UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla in the reaction catalyzed by phospho-MurNAc-pentapeptide translocase and in the membrane-catalyzed nascent peptidoglycan-synthetizing system. In the exchange reaction catalyzed by the translocase, the Rmax and Rmax/Km are 1.79 muM/min and 4.47 X 10(-2)/min, respectively, for UDP-MurNAc-pentapeptide and 1.81 muM/min and 4.46 X 10(-2)/min, respectively, for UDP-Mur-NAc-hexapeptide. In the synthesis of nascent peptidoglycan, the Vmax is 1.8 muM/min X 10(-2) for both the nucleotide-hexapeptide and -pentapeptide. The Vmax/Km is 5.6 X 10(-4) and 4.3 X 10(-4)/min for the nucleotide-pentapeptide and -hexapeptide, respectively. Schleifer, Hammes, and Kandler (Adv. Microb. Physiol. in press) observed that growth of S. aureus Copenhagen on a glycine-poor medium results in a peptidoglycan structure in which 20% of the lysine residues are substituted at the epsilon-amino group by L-alanine residues that do not participate in interpeptide bridge information. The in vitro studies demonstrate that UDP-MurNAc-Ala-DGlu-Lys(Nepsilon-Ala)-DAla-DAla is a possible precursor of the Nepsilon-Ala-Lys moiety.

Acetylglucosamine↗