Examples of sialic acid in the following topics:
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- HA proteins bind to cells with sialic acid on the membranes, such as cells in the upper respiratory tract or erythrocytes.
- First, it allows the recognition of target vertebrate cells, accomplished through the binding of these cells' sialic acid-containing receptors.
- HA binds to the monosaccharide sialic acid that is present on the surface of its target cells, which causes the viral particles to stick to the cell's surface.
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- Influenza viruses bind through hemagglutinin onto sialic acid sugars on the surfaces of epithelial cells, typically in the nose, throat, and lungs of mammals, and the intestines of birds (Step 1 in infection figure ).
- It is known that virions converge to the microtubule organizing center, interact with acidic endosomes, and finally enter the target endosomes for genome release.
- Once inside the cell, the acidic conditions in the endosome cause two events to happen:
- As before, the viruses adhere to the cell through hemagglutinin; the mature viruses detach once their neuraminidase has cleaved sialic acid residues from the host cell.
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- It cleaves sialic acid from glycoproteins on the surface of the host cell and allows the viral particles to leave the cell.
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- Pyruvic acid (CH3COCOOH) is an organic acid, a ketone, and the simplest of the alpha-keto acids.
- Pyruvic acid (CH3COCOOH; is an organic acid, a ketone, and the simplest of the alpha-keto acids.
- The carboxylate (COO−) anion of pyruvic acid.
- Pyruvic acid supplies energy to living cells through the citric acid cycle (also known as the Krebs cycle) when oxygen is present (aerobic respiration); when oxygen is lacking, it ferments to produce lactic acid.
- The cycle is also known as the citric acid cycle or tri-carboxylic acid cycle, because citric acid is one of the intermediate compounds formed during the reactions.
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- Aside from the 22 standard amino acids, there are many other amino acids that are called non-proteinogenic or non-standard.
- Aside from the 22 standard amino acids, there are many other amino acids that are called non-proteinogenic or non-standard .
- Examples include lanthionine, 2-aminoisobutyric acid, dehydroalanine, and the neurotransmitter gamma-aminobutyric acid.
- Nonstandard amino acids often occur as intermediates in the metabolic pathways for standard amino acids.
- A rare exception to the dominance of α-amino acids in biology is the β-amino acid beta alanine (3-aminopropanoic acid), which is used in plants and microorganisms in the synthesis of pantothenic acid (vitamin B5), a component of coenzyme A.
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- A great many organisms generate organic acids (such as lactate) as a byproduct of fermentation.
- The most commonly metabolized organic acids are the carboxylic acids, which are organic acids containing at least one carboxyl (-COOH) group.
- Many types of carboxylic acids can be metabolized by microbes, including:
- Fatty acid chains are converted to enoyl-CoA (catalyzed by acyl-CoA dehydrogenase).
- The fatty acid chain that is left over after the thiolation step can then reenter the β-oxidation pathway, which can cycle until the fatty acid has been completely reduced to acetyl-CoA.
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- These polymers are linear and unbranched, with each amino acid within the chain attached to two neighboring amino acids.
- Twenty-two amino acids are naturally incorporated into polypeptides and are called proteinogenic or natural amino acids.
- All amino acids are synthesized from intermediates in glycolysis, the citric acid cycle, or the pentose phosphate pathway.
- Amino acid synthesis depends on the formation of the appropriate alpha-keto acid, which is then transaminated to form an amino acid.
- Examples include lanthionine, 2-aminoisobutyric acid, dehydroalanine, and the neurotransmitter gamma-aminobutyric acid.
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- Microorganisms and plants can synthesize many uncommon amino acids and vitamins.
- Amino acids are biologically important organic compounds made from amine (-NH2) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid.
- About 500 amino acids are known which can be classified in many ways.
- Microorganisms and plants can synthesize many uncommon amino acids.
- While in plants, 1-aminocyclopropane-1-carboxylic acid is a small disubstituted cyclic amino acid that is a key intermediate in the production of the plant hormone ethylene.
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- Many organic compounds, like citric acid, are produced industrially by microorganisms.
- Citric acid (citrate) is an important substance in the Krebs cycle.
- For centuries, the source of citric acid were citrus fruits.
- The citric acid is then precipitated out of solution and regenerated.
- Explain how citric acid and other organic compounds are produced by the mold Aspergillus niger
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- Homolactic fermentation is the production of lactic acid from pyruvate; alcoholic fermentation is the conversion of pyruvate into ethanol and carbon dioxide; and heterolactic fermentation is the production of lactic acid as well as other acids and alcohols.
- However, more exotic compounds can be produced by fermentation, such as butyric acid and acetone.
- Pyruvic acid can be made from glucose through glycolysis, converted back to carbohydrates (such as glucose) via gluconeogenesis, or to fatty acids through acetyl-CoA.
- It can also be used to construct the amino acid alanine and be converted into ethanol.
- Pyruvic acid supplies energy to living cells through the citric acid cycle (also known as the Krebs cycle) when oxygen is present (aerobic respiration), and alternatively ferments to produce lactic acid when oxygen is lacking (fermentation).