PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 14197907

DEPOLYMERIZATION OF POLY-BETA-HYDROXYBUTYRATE BY INTRACELLULAR ENZYME SYSTEM.

J M MERRICK·M DOUDOROFF
View original source ↗Export metadata ↓

Abstract

Merrick, J. M. (State University of New York, Buffalo), and M. Doudoroff. Depolymerization of poly-beta-hydroxybutyrate by an intracellular enzyme system. J. Bacteriol. 88:60-71. 1964.-The poly-beta-hydroxybutyric acid contained in the "lipid granules" of Bacillus megaterium is hydrolyzed to d(-)-beta-hydroxybutyric acid by a complex enzyme system present in the soluble enzyme fraction of polymer-depleted cells of Rhodospirillum rubrum. This system consists of a thermostable "activator," a thermolabile "depolymerase," and an "esterase." Under certain conditions, the activator can be replaced by trypsin. Various chemical and physical treatments inactivate the "native lipid granules," and make them unsuitable as a substrate for the digestive enzymes. This inactivation of the granules is often expressed in the extent rather than the rate of their digestion, and is not correlated with the destruction of the polymer-synthesizing enzymes associated with the granules. The principal product of depolymerase action is d(-)-beta-hydroxybutyric acid, but small amounts of esterified products are also released. These are hydrolyzed by the esterase.

Explore related subjects

Bacillus megateriumCytoplasmic GranulesEnzymesEsterasesHydroxybutyratesMetabolismPolyestersPolymersResearchRhodospirillumRhodospirillum rubrumTrypsinPolyhydroxybutyratesBACILLUS MEGATERIUMENZYMESESTERASESEXPERIMENTAL LAB STUDYHYDROXYBUTYRATESMETABOLISMPOLYMERSRHODOSPIRILLUMJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J M MERRICK, M DOUDOROFF. 1964. DEPOLYMERIZATION OF POLY-BETA-HYDROXYBUTYRATE BY INTRACELLULAR ENZYME SYSTEM.. https://doi.org/10.1128/jb.88.1.60-71.1964

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Plasmid system for the intracellular production and purification of affinity-tagged proteins in Bacillus megaterium.

A multiple vector system for the intracellular high-level production of affinity tagged recombinant proteins in Bacillus megaterium was developed. The N- and C-terminal fusion of a protein of interest to a Strep II and a His(6)-tag is possible. Corresponding genes are expressed under the control of a xylose-inducible promoter in a xylose isomerase deficient host strain. The exemplatory protein production of green fluorescent protein (GFP) showed differences in produced and recovered protein amounts in dependence of the employed affinity tag and its N- or C-terminal location. Up to 9 mg GFP per liter shake flask culture were purified using one-step affinity chromatography. Integration of a protease cleavage site into the recombinant fusion protein allowed tag removal via tobacco etch virus (TEV) protease or Factor Xa treatment and a second affinity chromatographic step. Up to 274 mg/L culture were produced at 52 g CDW/L using a glucose limited fedbatch cultivation. GFP production and viability of the production host were followed by flow cytometry.

Bacillus megaterium↗
PubMed2007

Optimization of fermentation conditions for P450 BM-3 monooxygenase production by hybrid design methodology.

Factorial design and response surface techniques were used to design and optimize increasing P450 BM-3 expression in E. coli. Operational conditions for maximum production were determined with twelve parameters under consideration: the concentration of FeCl(3), induction at OD(578) (optical density measured at 578 nm), induction time and inoculum concentration. Initially, Plackett-Burman (PB) design was used to evaluate the process variables relevant in relation to P450 BM-3 production. Four statistically significant parameters for response were selected and utilized in order to optimize the process. With the 416C model of hybrid design, response surfaces were generated, and P450 BM-3 production was improved to 57.90x10(-3) U/ml by the best combinations of the physicochemical parameters at optimum levels of 0.12 mg/L FeCl(3), inoculum concentration of 2.10%, induction at OD(578) equal to 1.07, and with 6.05 h of induction.

Bacillus megaterium↗
PubMed2006

Toward understanding the inactivation mechanism of monooxygenase P450 BM-3 by organic cosolvents: a molecular dynamics simulation study.

Cytochrome P450 BM-3 from Bacillus megaterium is an extensively studied enzyme for industrial applications. A major focus of current protein engineering research is directed to improving the catalytic performance of P450 BM-3 toward nonnatural substrates of industrial importance in the presence of organic solvents or cosolvents. For the latter reason, it is important to study the effect of organic cosolvent molecules on the structure and dynamics of the enzyme, in particular, the effect of cosolvent molecules on the active site's structure and dynamics. In this paper, we have studied, using molecular dynamics (MD) simulations, the F87A mutant of P450 BM-3 in the presence of DMSO as cosolvent, to understand the role of the F87A substitution for its catalytic activity. This mutant exhibits an altered regioselectivity and substrate specificity compared with wild-type; however, it has lower tolerance toward DMSO. The simulation results offer an explanation for the DMSO sensitivity of the F87A mutant. Our simulation results show that the F87 side chain prevents the disturbance of the water molecule bound to the heme iron by DMSO molecules. The absence of the phenyl ring in F87A mutant promotes interactions of the DMSO molecule with the heme iron resulting in water displacement by DMSO at the catalytic heme center.

Bacillus megaterium↗