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J M MERRICK

Publications and source records attributed to J M MERRICK.

7 recordsLinked to original sources
PubMed1965

MORPHOLOGICAL CHANGES IN POLY-BETA-HYDROXYBUTYRATE GRANULES ASSOCIATED WITH DECREASED SUSCEPTIBILITY TO ENZYMATIC HYDROLYSIS.

Merrick, J. M. (State University of New York, Buffalo), D. G. Lundgren, and R. M. Pfister. Morphological changes in poly-beta-hydroxybutyrate granules associated with decreased susceptibility to enzymatic hydrolysis. J. Bacteriol. 89:234-239. 1965.-A complex enzyme system obtained from extracts of Rhodospirillum rubrum cells hydrolyzes poly-beta-hydroxybutyric acid (PHB) contained in native PHB granules isolated from Bacillus megaterium. A labile factor associated with the granules and necessary for depolymerization is easily destroyed by various chemical and physical treatments. Granules inactivated by these treatments were examined in an electron microscope. In all cases, the distinct morphological appearance of native granules was altered. Morphological changes were mainly characterized by membrane fragmentation, loss of coalescence, and surface alterations. These observations suggest that native PHB granules possess definite structural features, disruption of which results in decreased susceptibility of the polymer to enzymatic hydrolysis.

Bacillus megaterium↗
PubMed1964

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

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.

Bacillus megaterium↗