Glucose 1-phosphate (also called cori ester) is a
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
molecule with a
phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid .
The phosphate or orthophosphate ion is derived from phospho ...
group on the 1'-carbon. It can exist in either the α- or β-
anomer
In carbohydrate chemistry, a pair of anomers () is a pair of near-identical stereoisomers that differ at only the anomeric carbon, the carbon that bears the aldehyde or ketone functional group in the sugar's open-chain form. However, in order fo ...
ic form.
Reactions of α-glucose 1-phosphate
Catabolic
In
glycogenolysis
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase.
Mechanism
The ...
, it is the direct product of the reaction in which
glycogen phosphorylase
Glycogen phosphorylase is one of the phosphorylase enzymes (). Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Glycogen phosphory ...
cleaves off a
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
of
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
from a greater
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
structure. A deficiency of muscle glycogen phosphorylase is known as
glycogen storage disease type V
Glycogen storage disease type V (GSD5, GSD-V), also known as McArdle's disease, is a metabolic disorder, one of the metabolic myopathies, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its inci ...
(McArdle Disease).
To be utilized in cellular catabolism it must first be converted to
glucose 6-phosphate
Glucose 6-phosphate (G6P, sometimes called the Robison ester) is a glucose sugar phosphorylated at the hydroxy group on carbon 6. This dianion is very common in cells as the majority of glucose entering a cell will become phosphorylated in this wa ...
by the
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
phosphoglucomutase
Phosphoglucomutase () is an enzyme that transfers a phosphate group on an α-D-glucose monomer from the 1 to the 6 position in the forward direction or the 6 to the 1 position in the reverse direction.
More precisely, it facilitates the interconve ...
in a free equilibrium. One reason that cells form glucose 1-phosphate instead of glucose during glycogen breakdown is that the very polar phosphorylated glucose cannot leave the cell membrane and so is marked for intracellular catabolism.
Phosphoglucomutase-1 deficiency is known as
glycogen storage disease
A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by an enzyme deficiency affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.
GSD has ...
type 14 (GSD XIV).
Orphanet: Glycogen storage disease due to phosphoglucomutase deficiency
/ref>
Anabolic
In glycogenesis
Glycogenesis is the process of glycogen synthesis, in which glucose molecules are added to chains of glycogen for storage. This process is activated during rest periods following the Cori cycle, in the liver, and also activated by insulin in re ...
, free glucose 1-phosphate can also react with UTP to form UDP-glucose
Uridine diphosphate glucose (uracil-diphosphate glucose, UDP-glucose) is a nucleotide sugar. It is involved in glycosyltransferase reactions in metabolism.
Functions
UDP-glucose is used in nucleotide sugar metabolism as an activated form of glu ...
, by using the enzyme UDP-glucose pyrophosphorylase
Uridine diphosphate glucose (uracil-diphosphate glucose, UDP-glucose) is a nucleotide sugar. It is involved in glycosyltransferase reactions in metabolism.
Functions
UDP-glucose is used in nucleotide sugar metabolism as an activated form of glu ...
. It can then return to the greater glycogen structure via glycogen synthase
Glycogen synthase (UDP-glucose-glycogen glucosyltransferase) is a key enzyme in glycogenesis, the conversion of glucose into glycogen. It is a glycosyltransferase () that catalyses the reaction of UDP-glucose and (1,4--D-glucosyl)n to yield UD ...
.
β-Glucose 1-phosphate
β-Glucose 1-phosphate is found in some microbes. It is produced by inverting α-glucan phosphorylases including maltose phosphorylase
In enzymology, a maltose phosphorylase () is an enzyme that catalyzes the chemical reaction
:maltose + phosphate \rightleftharpoons D-glucose + beta-D-glucose 1-phosphate
Thus, the two substrates of this enzyme are maltose and phosphate, wher ...
, kojibiose phosphorylase
In enzymology, a kojibiose phosphorylase () is an enzyme that catalyzes the chemical reaction
:2-alpha-D-glucosyl-D-glucose + phosphate \rightleftharpoons D-glucose + beta-D-glucose 1-phosphate
Thus, the two substrates of this enzyme are koji ...
and trehalose phosphorylase and is then converted into glucose 6-phosphate
Glucose 6-phosphate (G6P, sometimes called the Robison ester) is a glucose sugar phosphorylated at the hydroxy group on carbon 6. This dianion is very common in cells as the majority of glucose entering a cell will become phosphorylated in this wa ...
by β-phosphoglucomutase.
See also
* Pentose phosphate pathway
The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt and the HMP Shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-pho ...
* Gerty Cori
Gerty Theresa Cori (; August 15, 1896 – October 26, 1957) was an Austro-Hungarian and American biochemist who in 1947 was the third woman to win a Nobel Prize in science, and the first woman to be awarded the Nobel Prize in Physiology or Me ...
References
{{Fructose and galactose metabolic intermediates
Organophosphates
Monosaccharide derivatives
Phosphate esters