Frog liver glycogen synthase. In vitro and In vivo interconversions between I and D forms

Castiñeiras, M J; Boronat, Albert; Itarte, Emilio; Guinovart, Joan J.; Pérez, María Honrubia

doi:10.1016/0305-0491(78)90002-0

Cited by 2 publications

(2 citation statements)

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“…It was established that glycogen synthase in these ciliates existed in two forms, G-6-P independent and dependent ( Fig. I), as has been reported on the enzymes of animal (5,9) and microbial sources (1 I , 26). The presence of glycolytic enzymes suggests that the reserve polysaccharide in the ciliates may be synthesized and degraded by a metabolic pathway similar to that in animals and Tetrahymena.…”

Section: Enzymatic Properties Of Phosphorylases From Animalsupporting

confidence: 67%

“…The authors are grateful to Dr. M. Kandatsu, Emeritus Professor of the University of Tokyo, for encouraging the present work, to Professor M. Miura, Miyazaki University, for affording facilities for using amino acid autoanalyzer, and to Dr. H. Ogawa, Miyazaki University, for inserting the permanent fistula in the goat. (9), then suspended so as to be 4% (v/v) in B-9 buffer solution (5). In experiments with radioactive compounds, starved (24 h) bacteria-free ciliate suspensions, prepared by the procedure described previously (lo), were used in addition to the washed cell suspensions.…”

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confidence: 99%

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Glycogen Phosphorylase and Synthase Activities of Rumen Ciliates of the Genus Entodinium

Hoshino¹,

Wakita²,

Iida³

1982

J Eukaryotic Microbiology

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Glycogen phosphorylase and synthase activities were detected in the sonic lysate of rumen ciliates of the genus Enfodiniurn. The ciliate phosphorylase had the following properties. The pH optimum was narrow and centered at pH 5.9. The activity was maximum at 30°C; above 40°C a rapid inactivation occurred. The K, value for glucose-1-phosphate (G-1-P) and for glycogen was 15 mM and 0.069% (w/v), respectively. NaF and ethylenediamine tetraacetic acid had no stimulative effect on the enzyme activity, though adenosine 3',5'-monophosphate and theophylline activated it. NaHSO, inhibited the enzyme activity at a concentration of 1 mM. The inhibition of glucose was noncompetitive for G-1-P. Glycolytic intermediates and nucleotides had a minor effect on phosphorylase activity. Glycogen synthase existed in two forms, glucose-6-phosphate dependent and independent forms; the proportion of the latter form increased with the decrease of reserve polysaccharide levels in the ciliates. Correlations between glycolytic enzyme activities included phosphorylase and synthase activities and reserve polysaccharide contents in the ciliates were determined, and a possible regulatory mechanism of polysaccharide synthesis and degradation was discussed.UMEN ciliates of the genus Entodinium accumulate a . polysaccharide structurally similar to amylopectin, with a unit chain length of 22-25 a-linked glucose residues (8,29). The polysaccharide content of the ciliates increases within 2 h after feeding and decreases gradually thereafter (28). The presence of several enzymes involving protozoal reserve polysaccharide metabolism has already been reported (1,7). However, the precise mechanism by which the protozoan polysaccharide is synthesized and degraded remains undetermined.In the present paper we describe the activities and some enzymatic properties of glycogen phosphorylase (EC 2.4.1.1) and glycogen synthase (EC 2.4.11) of sheep rumen ciliates of the genus Entodinium. Received 23 VI 81; accepted 6 VII 82

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Section: Enzymatic Properties Of Phosphorylases From Animalsupporting

confidence: 67%

mentioning

confidence: 99%