Takafumi Moriyama

Location of Streptococcus mutans in the Dentinal Tubules of Open Infected Root Canals

Examination by an immunofluorescent antibody technique has demonstrated that Streptococcus mutans gains entrance into the dentinal tubules of open root canals. It was observed that the distance of invasion from the canal walls ranged from an average of 493-524 μm to a maximum of 1050-1150 μm, depending on the subspecies of S. mutans. However, unidentified germs stained by Grams method invaded further than S. mutans.

δ-Aminolevulinic acid dehydratase of Mycobacterium phlei

Abstract δ-Aminolevulinic acid dehydratase (5-aminolevulinate hydro-lyase (adding 5-aminolevulinate and cyclizing), EC 4.2.1.24) was purified 160-fold from crude extracts of Mycobacterium phlei. The pH optimum was 9.2; the K m value for δ-aminolevulinic acid was 7.7 · 10 −5 M . Mg2+ was necessary for the maximum activity of the enzyme and EDTA inhibited the activity markedly. δ-Hydroxylevulinic acid, δ-hydroxy-γ-oxo- l -norvaline and levulinic acid inhibited the enzyme activity competitively. Inhibitory effect of α-ketoglutarate:glyoxylate carboligase activity on δ-aminolevulinic acid dehydratase activity was studied using the cell free extracts of M. phlei.

Neuraminidase activity in some bacteria from the human mouth

Abstract Fifty-eight strains of oral bacteria were tested for neuraminidase production by employing a sensitive method of enzyme assay. The activity of the strains of Streptococcus sanguis and Streptococcus mitis was particularly investigated. Neuraminidase was detected in fourteen of the thirty-five streptococci examined, and not in strains of any other genus. Some, but not all, strains of Strep, mitis and Strep, sanguis had neuraminidase activity. The origin of neuraminidase activity in saliva and the role in dental plaque formation are discussed.

Lysis of Streptococci by Lysozyme from Human Parotid Saliva and Sodium Lauryl Sulfate

Egg-white lysozyme (EC 3.2.1.17) has little effect on bacteria (including Streptococcus mitis and Streptococcus salivarius) indigeneous to the oral cavity of man (R. J. GIBBONS, J. D. STOPPELAAR, and L. HARDEN, J Dent Res 45:877, 1966). Recently, it has been shown that relatively lysozyme-resistant Streptococcus faecalis can be lysed by brief incubation with lysozyme, followed by the addition of sodium lauryl sulfate (SLS) or sodium chloride (R. H. METCALF and R. H. DEIBEL, J Bact 99:674, 1969). In our previous work (Y. IWAMOTO ET AL, J Dent Res 49:1104, 1970), lysozyme from human parotid saliva was purified successfully. It had a specific activity three and a half times greater than that of hen egg-white lysozyme and a composition that was different, especially in regard to tyrosine, serine, and glutamic acid contents. There have been no reports on the lysis of streptococci by parotid lysozyme. The purpose of this study was to observe the lysis of streptococci through the synergistic effect of SLS and lysozyme from human parotid saliva. Streptococci used in this study were S salivarius ATCC 9222, S mitis ATCC 9811, Streptococcus sanguis ATCC 10556, S sanguis ATCC 10557, and Streptococcus mutans strains GS-5, HS-6,* AHT, and FA-1.t Cells were inoculated from the thioglycolate agar stabs into a modified medium (K. S. BERMAN, R. J. GIBBONS, and J. NALBANDIAN, Arch Oral Biol 12:1133, 1967). After incubation for several hours at 37 C, cells in the exponential phase cultures were centrifuged and washed twice in cold distilled water. They were suspended in aliquots of 1/15 M Tris-HC1 buffer, pH 9.0. Lysis experiments were carried out according to the methods of Metcalf and Deibel (J Bact 99:674, 1969). Cells were resuspended in 4 ml lysing medium; the mixture contained TrisHC1 buffer (pH 9.0) in a final concentration of 1/15 M and 60 [tg of the purified parotid lysozyme. The reaction mixture was incubated at 37 C in a water bath with shaking. After ten minutes incubation, 0.1 ml of 0.32 M SLS was

Purification, general properties and two other catalytic activities of α-ketoglutarate:glyoxylate carboligase of Mycobacterium phlei

Abstract 1. 1. An α-ketoglutarate; glyoxylate carboligase was purified 200- to 250-fold from the sonic extracts of Mycobacterium phlei by (NH 4 ) 2 SO 4 fractionation, pH precipitation, starch block electrophoresis and column chromatography. 2. 2. From studies on decarboxylation from 14 C-labelled substrates, the enzyme seemed to catalyze the condensation of α-ketoglutarate and glyoxylate to form α-hydroxy-β-ketoadipic acid in the presence of thiamine pyrophosphate. α-Hydroxy-β-ketoadipic acid was spontaneously decarboxylated to δ-hydroxylevulinic acid in the presence of acid. 3. 3. The enzyme had an optimum pH of 6.3 in potassium phosphate buffer at 37°. K m values for α-ketoglutarate and glyoxylate were 2.0 mM and 3.2 mM, respectively. The isoelectric point, determined by isoelectric focusing, was 5.6. 4. 4. The enzyme activity was markedly activated by Mn 2+ and was activated to a small extent by Mg 2+ 5. 5. π-Chloromercuribenzene sulfonic acid, monoiodoacetic acid. EDTA and Zn 2+ inhibited the enzyme activity. 6. 6. The purified enzyme catalyzed α-ketoglutarate decarboxylase and α-ketoglutarate:acetaldehyde carboligase activities as well as α-ketoglutarate:glyoxylate carboligase activity.