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Glucokinase
KAMRAN
Velda Stokes
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Which has a higher affinity for glucose: hexokinase or glucokinase?
Hexokinase
Which of the following is characteristic of hexokinase (as opposed to glucokinase)?
It is not inducible by insulin
Differences of Hexokinase and glucokinase?
n nHexokinase: Its function is to make sure there is enough glc for the tissues, even in the presence of low blood glc concentrations, by phosphorylating all the glc concentration gradient between the blood and the intracellular environment. n nGlucokinase: Its function is to remove glc from the blood following a meal. n n(Hexokinase, Phosphofructokinase and pyruvate kinase, are 3 regulatory enzymes of glycolysis.) nLiver has an additional enzyme, glucokinase, that phosphorylate only glc n n1. Glucokinase has a high Km because it phosphorylates glc only when its concentration is high. This occurs during the brief period after consumption of a carbohydrate rich meal, when high glc are delivered by portal vein. n n2. Glucokinase has a high Vmax, allowing the liver to remove effectively this flood of glc from the portal blood. So this prevents extreme hyperglycemia after meals. n
What substrate is converted into glucose 6 phosphate by the enzyme hexokinase?
Glucose, although only the liver uses a different enzyme, called glucokinase which does the same thing.
Describe how hexokinase works?
It can work maximally at low glucose concentrations (fasting levels of glucose are 3-5mM) so that it is always working at vmax
Why is glucokinase inactive in the nucleus?
Glucokinase Regulatory Protein is found in the nucleus which binds glucokinase to inactive it
What is hexokinase?
a hexokinase is an enzyme that catalyzes the phosphorylation of hexoses.
where is glucokinase active intracellularly?
in the cytosol
What enzyme is responsible for aerobic respiration?
There are very many enzymes involved. A few from glycolysis are: hexokinase and glucokinase, phosphohexose isomerase, phosphofructokinase, pyruvate kinase; from pyruvate decarboxylation are pyruvate dehydrogenase phosphatase and pyruvate dehydrogenase kinase; and a few from the Kreb's cycle are: aconitase, alpha-ketoglutamate dehydrogenase, succinate thiokinase, and fumarase.
What is the glucose sensor in B-cells Why?
glucokinase. glucokinase has a high km(low affinity for glucose) so glucokinase only phosphorylates glucose when blood glucose is high, such as after a meal. As such, it makes sense that this would be sensor for B-cells
How does ATP inhibit hexokinase?
No it is not!
What is the importance of enzyme vmax?
It helps maintain maximum availibility in some objects.Such as vechiles can use V/Max to maitain higher speeds or higher RPM's.
