Identification, Preliminary Characterization, and Evidence for Regulation of Invertase in Streptococcus mutans

– Supragingival human dental plaque was ecllected from patients with evidence of caries. The plaque was frozen and stored at‐20°C. Pooled plaque was homogenized in acelate buffer pH 5.0 in an ice‐water bath. By incubating the homogenate at pH 5.0 with [U‐°C]‐sucrose the formation fo glucose and fructose was followed. Incubation in acetate buffer at pH 5.0 eliminated the glycosyltransferase activities adn teh glycolytic pathway. Normal Michaclis‐Menten kinetics were observed until about 40 mM sucrose. At highert concentration of sucrose, excess substrate inhibition occurred. Storage of the homogenate at −20° C resulted in decrease of the invertase activity with time.

Section: Discussionmentioning

confidence: 46%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Method for determination of invertase acitivity in homogentes of human dental plaque

Fiehn

Moe

1981

“…A mixture of glucose and fructose gave a greater rate of acid production than did the equivalent concentration of sucrose and this indicates that a limidng stage in acid formation may occur at an extracellular sucrose hydrolysis step. Some ofthe sucrose is probably transported by permease systems (27) and the transport process itself could be rate litniting. BIRKHED (3) obtained a similar rate from 0.1 M sucrose compared with a mixture of glucose and fructose, showing that hydrolysis of sucrose is not rate limiting at higher concentrations.…”

Section: Metabolism Of Oligosaccharidesmentioning

confidence: 99%

Effects of 2‐deoxy D‐glucose and other sugar analogues on acid production from sugars by human dental plaque bacteria

Roberts

Hayes

1980

– Solutions (10–25 μM) of D‐glucose, N‐acetyl‐D‐glucosamine, D‐fructose, sucrose, maltose, lactose and maltotriose were readily metabolised to acid (140–250 μmol H+ wet g−1h−1) by anacrobic suspensions of fresh plaque at pH 7.5. D‐Mannose, D‐galactose, D‐glucosamine and trehalose were broken down more slowly (35–115 μmol H+ wet g−1h−1). Inhibition of this acid production occurred on adding excess amounts of 2‐deoxy‐D‐glucose or 5‐thio‐D‐glucose. Similarly, excess amounts of cellobiose specifically inhibited acid liberation from lactose. No acid production was detected from a number of other sugars and sugar derivatives, some of which may be useful sucrose substitutes.

“…This free sugar may be present because of transport by a mechanism other than the PTS system, or it could be formed as a result of phosphatase action on 2DG-6-phosphate (26). However, this latter process is energetically wasteful, and support for the former proposal comes from the fmding of TANZEK et al (25) that invertase activity can be located intracellularly in Strep, mutans thereby implying that free sugar (sucrose) can be transported into the cell.…”

Section: Discnssiojimentioning

confidence: 99%

Phosphoenolpyruvate‐dependent glucose phosphotransferase activity in Streptococcus mitis ATCC 903

Roberts

Linder

1980

– A constitutive phosphoenolpyruvate (PEP)‐dependent glucose phosphotransferase system was found in decryptified cells of Strep. mitis. The system displayed saturation kinetics and the apparent Km value for the non‐fermentable analogue 2‐deoxyglucose (2DG) was 0.4 mm. Sodium fluoride inhibited the activity when 2‐phosphoglycerate was used as the energy source instead of PEP, Intact cells accumulated 2DG and also a derivative that behaved chromatographically like 2DG‐6‐phosphate. PEP‐dependent glucose phosphotransferase activity was also demonstrated in freshly collected plaque.