Browsing Pathways

Most bacteria, including Escherichia coli, are composed of murein which protects and stabilizes the cell wall. Over half of the murein is broken down by Escherichia coli and recycled for the next generation. The main muropeptide is GlcNAc-anhydro-N-acetylmuramic acid (anhMurNAc)-l-Ala-γ-d-Glu-meso-Dap-d-Ala which enters the cytoplasm by AmpG protein. The peptide is then released from the muropeptide. 1,6-Anhydro-N-acetylmuramic acid (anhMurNAc) is recycled by its conversion to N-acetylglucosamine-phosphate (GlcNAc-P). The sugar is phosphorylated by anhydro-N-acetylmuramic acid kinase (AnmK) to produce MurNAc-P. Etherase cleaves MurNAc-P to produce N-acetyl-D-glucosamine 6-phosphate. The product can undergo further degradation or be recycled into peptidoglycan monomers. The pathway's final product is a peptidoglycan biosynthesis precursor, UDP-N-acetyl-α-D-muramate. The enzyme muropeptide ligase (mpl), attaches the recovered Ala-Glu-DAP tripeptide to the precursor UDP-N-acetyl-α-D-muramate to return to the peptide to the peptidoglycan biosynthetic pathway to synthesize the cell wall.

Most bacteria, including Escherichia coli, are composed of murein which protects and stabilizes the cell wall. Over half of the murein is broken down by Escherichia coli and recycled for the next generation. The main muropeptide is GlcNAc-anhydro-N-acetylmuramic acid (anhMurNAc)-l-Ala-γ-d-Glu-meso-Dap-d-Ala which enters the cytoplasm by AmpG protein. The peptide is then released from the muropeptide. 1,6-Anhydro-N-acetylmuramic acid (anhMurNAc) is recycled by its conversion to N-acetylglucosamine-phosphate (GlcNAc-P). The sugar is phosphorylated by anhydro-N-acetylmuramic acid kinase (AnmK) to produce MurNAc-P. Etherase cleaves MurNAc-P to produce N-acetyl-D-glucosamine 6-phosphate. The product can undergo further degradation or be recycled into peptidoglycan monomers. The pathway's final product is a peptidoglycan biosynthesis precursor, UDP-N-acetyl-α-D-muramate. The enzyme muropeptide ligase (mpl), attaches the recovered Ala-Glu-DAP tripeptide to the precursor UDP-N-acetyl-α-D-muramate to return to the peptide to the peptidoglycan biosynthetic pathway to synthesize the cell wall.

Methylhistidine is a modified amino acid that is produced in myocytes during the methylation of actin and myosin. It is also formed from the methylation of L-histidine, which takes the methyl group from S-adenosylmethionine and forms S-adenosylhomocysteine as a byproduct. After its formation in the myocytes, methylhistidine enters the blood stream and travels to the kidneys, where it is excreted in the urine. Methylhistidine is present in the blood and urine in higher concentrations after skeletal muscle protein breakdown, which can occur due to disease or injury. Because of this, it can be used to judge how much muscle breakdown is occurring. Methylhistidine levels are also affected by diet, and may differ between vegetarian diets and those containing meats.

11-beta-Hydroxylase Deficiency, also called congenital adrenal hyperplasia (CAH), is an autosomal recessive disorder and caused by a defective 11-beta-hydroxylase. 11-beta-hydroxylase catalyzes the conversion of cortexolone into cortisol which is useful for maintaining blood sugar levels and suppressing inflammation. This disorder is characterized by a large accumulation of cortexolone in the endoplasmic reticulum (ER). Symptoms of the disorder include abnormality of hair growth rate and menstrual cycle. It is estimated that 11-beta-hydroxylase deficiency affects 1 in 100,000 to 200,000 newborns.

11-beta-Hydroxylase Deficiency, also called congenital adrenal hyperplasia (CAH), is an autosomal recessive disorder and caused by a defective 11-beta-hydroxylase. 11-beta-hydroxylase catalyzes the conversion of cortexolone into cortisol which is useful for maintaining blood sugar levels and suppressing inflammation. This disorder is characterized by a large accumulation of cortexolone in the endoplasmic reticulum (ER). Symptoms of the disorder include abnormality of hair growth rate and menstrual cycle. It is estimated that 11-beta-hydroxylase deficiency affects 1 in 100,000 to 200,000 newborns.

11-beta-Hydroxylase Deficiency, also called congenital adrenal hyperplasia (CAH), is an autosomal recessive disorder and caused by a defective 11-beta-hydroxylase. 11-beta-hydroxylase catalyzes the conversion of cortexolone into cortisol which is useful for maintaining blood sugar levels and suppressing inflammation. This disorder is characterized by a large accumulation of cortexolone in the endoplasmic reticulum (ER). Symptoms of the disorder include abnormality of hair growth rate and menstrual cycle. It is estimated that 11-beta-hydroxylase deficiency affects 1 in 100,000 to 200,000 newborns.

(3S)-11-cis-3-hydroxyretinal is one of three chromophores, which then associate with rhodopsins. Specifically, this chromophore associates with the Rh1 rhodopsin, a blue/green sensitive visual pigment found in 6 of the 8 photoreceptor cells in Drosophila melanogaster. The production of this chromophore begins with zeaxanthin obtained from Drosophila’s dietary sources. This lipid is broken down into (3R)-11-cis-3-hydroxyretinal and (3R)-all-trans-3-hydroxyretinal by a carotenoid isomerooxygenase. The (3R)-cis-3-hydroxyretinal is then attached to a retinoid binding protein, and this complex goes on to be used in the visual cycle of the organism. However, (3R)-all-trans-3-hydroxyretinal must be further processed. It too binds to a retinoid binding protein that will remain unchanged through the rest of the reactions. First, this complex will have a hydrogen added by a photoreceptor dehydrogenase in order to form (3R)-all-trans-3-hydroxyretinol, and then a photoreceptor epimerase will invert its stereochemistry to form (3S)-all-trans-3-hydroxyretinol. From here, an unknown protein, an oxidoreductase that transposes C=C bonds, will form (3S)-11-cis-3-hydroxyretinol. Finally, another photoreceptor dehydrogenase removes a hydrogen from that complex, forming the final product, (3S)-11-cis-3-hydroxyretinal. This complex then joins (3R)-11-cis-3-hydroxyretinal in the visual cycle.

17-alpha-hydroxylase deficiency, also known as congenital adrenal hyperplasia (CAH) due to 17-alpha-hydroxylase deficiency or congenital adrenal hyperplasia type 5, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the steroidogenesis pathway. It is caused by a mutation in the CYP17A1 gene which encodes the enzyme steroid 17-alpha-hydroxylase. This enzyme hydroxylates both progesterone and pregnenolone into 17-hydroxyprogesterone and 17a-hydroxypregnenolone respectively in the mitochondria, as well as hydroxylating 21-deoxycortisol to 11b-hydroxyprogesterone within the endoplasmic reticulum. When mutated, it leads to an accumulation of pregnenolone, progesterone, deoxycorticosterone and 11-dehydrocorticosterone throughout the cell. 17-alpha hydroxylase deficiency is characterized by a deficiency of sex steroids, as well as glucocorticoids. Symptoms include male undervirilization, as well as lack of development during puberty including amenorrhea for females. Low levels of potassium in the blood due to the increased levels of mineralocorticoids can occur, as well as hypertension. Treatment with dexamethasone has been able to normalize blood pressure and blood potassium levels. It is estimated that 17-alpha-hydroxylase deficiency affects 1 in 1,000,000 individuals.

17-alpha-hydroxylase deficiency, also known as congenital adrenal hyperplasia (CAH) due to 17-alpha-hydroxylase deficiency or congenital adrenal hyperplasia type 5, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the steroidogenesis pathway. It is caused by a mutation in the CYP17A1 gene which encodes the enzyme steroid 17-alpha-hydroxylase. This enzyme hydroxylates both progesterone and pregnenolone into 17-hydroxyprogesterone and 17a-hydroxypregnenolone respectively in the mitochondria, as well as hydroxylating 21-deoxycortisol to 11b-hydroxyprogesterone within the endoplasmic reticulum. When mutated, it leads to an accumulation of pregnenolone, progesterone, deoxycorticosterone and 11-dehydrocorticosterone throughout the cell. 17-alpha hydroxylase deficiency is characterized by a deficiency of sex steroids, as well as glucocorticoids. Symptoms include male undervirilization, as well as lack of development during puberty including amenorrhea for females. Low levels of potassium in the blood due to the increased levels of mineralocorticoids can occur, as well as hypertension. Treatment with dexamethasone has been able to normalize blood pressure and blood potassium levels. It is estimated that 17-alpha-hydroxylase deficiency affects 1 in 1,000,000 individuals.

17-alpha-hydroxylase deficiency, also known as congenital adrenal hyperplasia (CAH) due to 17-alpha-hydroxylase deficiency or congenital adrenal hyperplasia type 5, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the steroidogenesis pathway. It is caused by a mutation in the CYP17A1 gene which encodes the enzyme steroid 17-alpha-hydroxylase. This enzyme hydroxylates both progesterone and pregnenolone into 17-hydroxyprogesterone and 17a-hydroxypregnenolone respectively in the mitochondria, as well as hydroxylating 21-deoxycortisol to 11b-hydroxyprogesterone within the endoplasmic reticulum. When mutated, it leads to an accumulation of pregnenolone, progesterone, deoxycorticosterone and 11-dehydrocorticosterone throughout the cell. 17-alpha hydroxylase deficiency is characterized by a deficiency of sex steroids, as well as glucocorticoids. Symptoms include male undervirilization, as well as lack of development during puberty including amenorrhea for females. Low levels of potassium in the blood due to the increased levels of mineralocorticoids can occur, as well as hypertension. Treatment with dexamethasone has been able to normalize blood pressure and blood potassium levels. It is estimated that 17-alpha-hydroxylase deficiency affects 1 in 1,000,000 individuals.