G6PD deficiency is a genetic disorder that most often affects males. G6PD helps red blood cells work. It also protects them from substances in the blood that could harm them. Without enough G6PD to protect them, the red blood cells break apart. This is called hemolysis hih-MOL-ih-sis.
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Species distribution[ edit ] G6PD is widely distributed in many species from bacteria to humans. In higher plants, several isoforms of G6PDH have been reported, which are localized in the cytosol , the plastidic stroma , and peroxisomes. Phosphorus is shown in orange. Oxygen atoms of crystallographic waters are shown as red spheres.
The conserved 9-peptide sequence of G6PD, and the partially conserved 5-residue sequence of G6PD are shown in cyan and magenta respectively. All other amino acids from G6PD are shown in black. Hydrogen bonding and electrostatic interactions are shown by green dashed lines. All green dashes represent distances of less than 3. G6PD is generally found as a dimer of two identical monomers see main thumbnail.
The proline at position is thought to play a crucial role in positioning Lys correctly with respect to the substrate, G6P. In the two crystal structures of normal human G6P, Pro is seen exclusively in the cis confirmation, while in the crystal structure of one disease causing mutant variant Canton RL , Pro is seen almost exclusively in the trans confirmation.
Thus, mutations in these critical areas are possible without completely disrupting the function of G6PD. Its purpose in the enzyme catalyzed reaction has been unclear for many years. However, this was shown to be incorrect.
In particular, there is a strong network of hydrogen bonding with electrostatic charges being diffused across multiple atoms through hydrogen bonding with 4 water molecules see figure. Hydrogen bonding and electrostatic interaction network green. All green dashes represent distances less than 3. All green dashes represent distances less than 4.
Slightly different view than the first panel. The oxygen atoms of crystallographic water molecules are shown as red spheres. The conserved 9-peptide sequence of G6PD is show in cyan. The structural site has been shown to be important for maintaining the long term stability of the enzyme. Thus, regulation of G6PD has downstream consequences for the activity of the rest of the pentose phosphate pathway. Glucosephosphate dehydrogenase is stimulated by its substrate G6P.
Yeast G6PD is inhibited by long chain fatty acids according to two older publications   and might be product inhibition in fatty acid synthesis which requires NADPH. G6PD is negatively regulated by acetylation on lysine Lys , an evolutionarily conserved residue. The K acetylated G6PD is incapable of forming active dimers and displays a complete loss of activity. The isoform, G6PDH, is regulated by transcription and posttranscription factors.
Many variants of G6PD, mostly produced from missense mutations , have been described with wide-ranging levels of enzyme activity and associated clinical symptoms. Two transcript variants encoding different isoforms have been found for this gene.
This enzyme, glucosephosphate dehydrogenase GPD , is essential for assuring a normal life span for red blood cells, and for oxidizing processes. This enzyme deficiency may provoke the sudden destruction of red blood cells and lead to hemolytic anemia with jaundice following the intake of fava beans, certain legumes and various drugs see a complete list of drugs and foodstuffs to avoid. The defect is sex-linked, transmitted from mother usually a healthy carrier to son or daughter, who would be a healthy carrier too; see a diagram of inheritance probabilities. Please note that there are more than genetic variants of the deficiency.
Deficiencia de glucosa -6- fosfato deshidrogenasa
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