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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.

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.

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.

After treatment of isolated cells walls of Methanobacterium thermoautotrophicum with sodium hydroxide or anhydrous hydrazine, water soluble glycan strands were obtained. These consisted of alternating (beta 1-3)-linked D-glucosamine and (alpha 1-3)-linked L-talosaminuronic acid residues and their length was about 25 disaccharides. Some of the L-talosaminuronic acid residues remained linked to either glutamic acid or the peptides N-gamma-glutamylalanine and N epsilon-(gamma-glutamylalanyl)lysine, indicating that the peptide moiety of pseudomurein is bound to the carboxyl group of talosaminuronic acid via the amino group of glutamic acid.

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.

Biochemical and chemotaxonomical studies were performed on some streptococci from frozen peas and bovine mastitis in an attempt to clarify their taxonomy. The results of the present and earlier studies indicate the pea and mastitis isolates represent two new species of the genus Streptococcus. The isolates from frozen peas are named Streptococcus plantarum sp. nov. and those from mastitis, Streptococcus garvieae sp. nov. The type strains are NCDO 1869 and NCDO 2155, respectively.

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.

Salicylaldoxime (2 x 10(-3)m and less) inhibits cyclic photophosphorylation in intact Chlorella cells severely whereas photosynthetic O(2)-evolution and (14)CO(2)-fixation is hardly affected. Cyclic photophosphorylation in vivo was measured by following anaerobic light dependent glucose uptake. A similar difference in susceptibility has been observed with carbonylcyanide-p-trifluoromethoxyphenylhydrazone. Various controls exclude the possibility that the difference in inhibition was caused by differing experimental conditions or, in the case of glucose assimilation, by an inhibition of a reaction other than photophosphorylation.There also exists a great difference in light saturation of cyclic photophosphorylation and photosynthesis. Evidence is reported that at light saturation of glucose uptake light driven cyclic phosphorylation is indeed the limiting reaction.The results are considered as evidence that cyclic photophosphorylation does not contribute ATP stoichiometrically to photosynthetic CO(2)-fixation.

In a study of the mureins of coryneform bacteria (Arthrobacter, Brevibacterium, Cellulomonas, Corynebacterium, Erysipelothrix), 21 threonine-containing strains were found. In several of the strains the amino acid and amino sugar composition of the murein was muramic acid (Mur), glucosamine (GlcNH(2)), d-Glu, l-Lys, l-Thr, and Ala in a molar ratio of 1:1:1:1:1:4 or 5, and in several other strains it was Mur, GlcNH(2), d-Glu, l-Lys, l-Thr, Ala, and l-Ser in a molar ratio of 1:1:1:1:1:3:1. The amino acid sequence of the mureins was determined by analyzing the oligopeptides derived from partial acid hydrolysates. It was shown that there were five different murein types. The peptide subunits attached to the muramic acid are the same, namely l-Ala-d-GluNH(2)-l-Lys-d-Ala. In one strain, the alpha-carboxyl group of d-Glu is substituted by d-alanine amide. The interpeptide bridges of the different types consist of the peptides l-Ala-l-Thr-l-Ala, l-Ala-l-Thr, l-Ala-l-Ala-l-Thr, l-Ala-l-Ala-l-Ala-l-Thr, or l-Ala-l-Thr-l-Ser which are bound through their C-termini (l-Ala, l-Thr, l-Ser) to the epsilon-amino group of l-Lys of one peptide subunit and by their N-termini (l-Ala) to the C-terminal d-Ala of an adjacent peptide subunit. Determination of the N- and C-terminal groups in the mureins showed that about 15 to 30% of the interpeptide bridges are not cross-linked.