Studies on Glucose Phosphorylation in Rat Liver<sup>*</sup>

DiPietro, David L.; Sharma, C.B.; Weinhouse, Sidney

doi:10.1021/bi00909a014

Cited by 196 publications

(45 citation statements)

References 32 publications

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“…This pointed to the existence of an HK with a much higher Km for glucose than the values of 0.01-0.1 mmol/1 for HKs known at the time. This enzyme activity (HK IV or GK) was subsequently identified in liver homogenates by Weinhouse and co-workers [4] and the enzyme purified by Sols and colleagues [5,6] in [1963][1964][1965][1966]. The name glucokinase was adopted, partly in deference to Carl Cori, and partly to distinguish its unique properties amongst HKs viz lower Mr (molecular weight), higher Km for glucose (12 mmol/1), sigmoid glucose concentration-reaction velocity relationship (Hill coefficient 1.6), and absence of inhibition by the reaction product glucose 6-phosphate.…”

Section: Discovery Of Liver Glucokinasementioning

confidence: 94%

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Randle

1993

Diabetologia

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Section: Discovery Of Liver Glucokinasementioning

confidence: 94%

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Randle

1993

Diabetologia

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“…Sufficient DEAE-cellulose was packed into 8-mm diameter glass columns to give 2 ml of resin/ml of tissue extract-a maximum of 4 mg of protein/ml resin. The columns were equilibrated with 5 (Fig. 1).…”

Section: Methodsmentioning

confidence: 99%

“…1) has been studied intensively and is particularly complex, having regulatory properties (22) and tissue specific isozvmes (13,27). Most noteworthy of the isozymes is the liver glucokinase of nonruminant animals which is thought to regulate blood glucose levels (2,5). Its relatively high Michaelis constant (Kin = 10-40 mm glucose) is related to the high levels of glucose found in liver and in the blood.…”

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confidence: 99%

Hexokinase from Maize Endosperm and Scutellum

Cox¹,

Dickinson²

1973

Plant Physiol.

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Hexokinase (EC 2.7.1.1) was isolated from endosperm and scutellum of developing and germinating maize (Zea mays) seeds. With fructose as the variable substate, Michaelis constant values for the scutellum enzyme were about onethird those of the endosperm enzyme (0.05 versus 0.15 mM), and no developmental differences were observed. With glucose as the variable substrate, Michaelis constant values were all in the range 0.1 to 0.2 mM. The enzyme preparation from germinating scutellum was studied further; when glucose was varied over a wide range, a Michaelis constant of 3.4 mM was observed in addition to the much lower Michaelis constant noted above. This low affinity binding of glucose may have regulatory significance and may indicate the presence of a glucokinase in addition to hexokinase.The hexokinase reaction represents the first step in the incorporation of hexoses into respiratory and biosynthetic pathways of plants and animals. Mammalian hexokinase (EC 2.7. 1. 1) has been studied intensively and is particularly complex, having regulatory properties (22) and tissue specific isozvmes (13,27). Most noteworthy of the isozymes is the liver glucokinase of nonruminant animals which is thought to regulate blood glucose levels (2, 5). Its relatively high Michaelis constant (Kin = 10-40 mm glucose) is related to the high levels of glucose found in liver and in the blood. There is also information concerning hexokinase from yeast (7,23) and various tissues of higher plants (17,25).Hexokinase in seeds of cereal grains is of particular interest. In developing seeds, this enzyme is the first step in starch biosynthesis because translocated sucrose is hydrolyzed to its constituent hexoses prior to absorption by endosperm tissue (28). In germinating seeds, starch hydrolysis produces glucose which is converted to sucrose in the scutellum (9). Hence, scutellum hexokinase is important during germination as the first step in conversion of glucose to sucrose, and fructose would not be a major substrate during germination.The relatively few studies of hexokinase from seeds of cereal grains include reports on properties of the wheat germ enzyme (18. 25) and a Ph.D. thesis concerned with the maize scutellum enzyme (12). Maize endosperm hexokinase increases rapidly at the time of starch accumulation (3,30) and is present at a relatively low level during germination (3). However, there seems to be no published information on kinetic properties of the endosperm enzyme. and hence no knowledge whether the endo-'This work was supported by National Science Foundation Grant GB8764 and the Illinois Agriculture Experiment Station. sperm and scutellum enzymes differ kinetically because of metabolic differences within the tissues. Some kinetic properties of hexokinase from maize endosperm and scutellum are presented in this paper. MATERIALS AND METHODSChemicals. The chemicals used were of reagent grade and were dissolved in glass distilled water. Chemicals purchased from Sigma Chemical Company were N-2-hydroxyethyl-piperazine-N'-2-etha...

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“…These have been resolved by electrophoresis (Katzen et al, 1965) into three 'low Kmn' hexokinases (EC 2.7.1.1) and one 'high-Km' glucokinase (EC 2.7.1.2). The presence of this high-Kmn, insulin-inducible, glucokinase has been correlated with the responsiveness of the liver to glucose at concentrations in the range normally observed for this sugar in the blood (Cahill et al, 1959;Di Pietro et al, 1962). This apparent duplication of glucose-phosphorylating capacities, considered together with the low total hexokinase activities (in the rat), has stimulated the suggestion that glucokinase alone is associated with the parenchymal cells and that the hexokinases occur in the mesenchymatous tissue (Kupffer cells etc.)…”

mentioning

confidence: 93%

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Crisp

Pogson

1972

Biochemical Journal

130

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Parenchymal cells contain both glucose 6-phosphatase and fructose 1,6-diphosphatase. The non-parenchymal fraction appears to contain fructose 1,6-diphosphatase, but is devoid of glucose 6-phosphatase. 8. No aldolase A was detectable in the whole liver. Aldolase B occurs in both parenchymal and non-parenchymal tissue. 9. Parenchymal cells prepared by mechanical disruption ofmouse liver with 20 % polyvinyl alcohol exhibit a similar enzyme profile to those prepared enzymically. 10. The methodology involved in the preparation of isolated liver cells is discussed. The importance of the measurement of several parameters as criteria for establishing the viability of parenchymal cells is stressed. 11. The metabolic implications of the results in the present study are discussed.

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Studies on Glucose Phosphorylation in Rat Liver^*

Cited by 196 publications

References 32 publications

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Hexokinase from Maize Endosperm and Scutellum

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

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Studies on Glucose Phosphorylation in Rat Liver*

Cited by 196 publications

References 32 publications

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Glucokinase and candidate genes for Type 2 (non-insulin-dependent) diabetes mellitus

Hexokinase from Maize Endosperm and Scutellum

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

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Product

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Studies on Glucose Phosphorylation in Rat Liver^*