Miraculin: Difference between revisions
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Fujr Ibrahim (talk | contribs) New page: == <h3><span style="color: #800020;"> Miraculin, a taste-deceiving protein </span> </h3> == == <h4><span style="color: #800020;"> Introduction to Miraculin </span> </h4> == <p> Miracle?... |
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== <h4><span style="color: #800020;"> Introduction to Miraculin, a taste-deceiving protein </span> </h4> == | |||
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<p> Miracle? I think you mean ''Miraculin''. </p> | <p> Miracle? I think you mean ''Miraculin''. </p> | ||
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<P> Miraculin’s deceptive properties have been exploited by several companies as sugar substitutes. However, the American Food and Drug Administration banned the use of miraculin after labeling it as an additive <ref> https://www.accessdata.fda.gov/cms_ia/importalert_120.html </ref>. This prevented its commercial use in the food industry. </p> | <P> Miraculin’s deceptive properties have been exploited by several companies as sugar substitutes. However, the American Food and Drug Administration banned the use of miraculin after labeling it as an additive <ref> https://www.accessdata.fda.gov/cms_ia/importalert_120.html </ref>. This prevented its commercial use in the food industry. </p> | ||
See [[Trypsin inhibitor]]. | |||
== <h4><span style="color: #800020;"> Miraculin’s Structure </span></h4> == | == <h4><span style="color: #800020;"> Miraculin’s Structure </span></h4> == | ||
Miraculin is composed of 191 amino acid residues linked primarily by peptide bonds, having a molecular weight of about 28 kDa. Sarroch Theerasil et al <ref> https://www.jbc.org/content/263/23/11536.full.pdf+html </ref> use HPLC profiles and SDS-PAGE analyses to prove this. | Miraculin is composed of 191 amino acid residues linked primarily by peptide bonds, having a molecular weight of about 28 kDa. Sarroch Theerasil ''et al'' <ref> https://www.jbc.org/content/263/23/11536.full.pdf+html </ref> use HPLC profiles and SDS-PAGE analyses to prove this. | ||
Miraculin is a homodimer made by two chains that have two N-glycosylated Asn residues and are cross-linked through a disulfide bridge. Miraculin can also exist in a tetramer form. | Miraculin is a homodimer made by two chains that have two N-glycosylated Asn residues and are cross-linked through a disulfide bridge. Miraculin can also exist in a tetramer form. | ||
== <h4><span style="color: #800020;"> Predictivley-Modeled Structure of Miraculin </span></h4> == | == <h4><span style="color: #800020;"> Predictivley-Modeled Structure of Miraculin </span></h4> == | ||
<p>Antonella Paladino et al’s article “Molecular modeling of miraculin: Structural analyses and functional hypotheses” <ref>PMID: 18158914 </ref> models the structure of miraculin by comparative | <p>Antonella Paladino et al’s article “Molecular modeling of miraculin: Structural analyses and functional hypotheses” <ref>PMID: 18158914 </ref> models the structure of miraculin by comparative modeling and molecular docking techniques as no structural data for miraculin are available. | ||
The article concludes that two histidine residues, located in exposed regions, are the main responsible of miraculin activity. The assays run in the journal also conclude that the miraculin dimer assumes a widely open conformation in an acidic environment. </p> | The article concludes that two histidine residues, located in exposed regions, are the main responsible of miraculin activity. The assays run in the journal also conclude that the miraculin dimer assumes a widely open conformation in an acidic environment. </p> | ||
<p> Although not directly apparent in the model, four hydrogen bonds are present between the two dimers. In linear form, only one hydrogen bond is possible between the dimers. The different conformations can be used to compare the closed and open conformations of miraculin in figure 2 of the journal. The prevalence of cysteine and histidine residues are highlighted in the figure as well. </p> | <p> Although not directly apparent in the model, four hydrogen bonds are present between the two dimers. In linear form, only one hydrogen bond is possible between the dimers. The different conformations can be used to compare the closed and open conformations of miraculin in figure 2 of the journal. The prevalence of cysteine and histidine residues are highlighted in the figure as well. </p> | ||
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Several miraculin-like proteins (MLPs) have been identified and are classified as “miraculin-like” based on amino-acid sequence alignment with that of miraculin. MLPs and miraculin are categorized into the Kunitz-type soybean trypsin inhibitor (STI) family. Features common to the Kunitz-type soybean trypsin inhibitor (STI) family include the presence of disulfide bridges --which are apparent in miraculin models-- and the inhibition of trypsin and chymotrypsin. Examples include MLPs extracted from ''Murraya koenigii'' and ''Vitis vinifera plants''. | Several miraculin-like proteins (MLPs) have been identified and are classified as “miraculin-like” based on amino-acid sequence alignment with that of miraculin. MLPs and miraculin are categorized into the Kunitz-type soybean trypsin inhibitor (STI) family. Features common to the Kunitz-type soybean trypsin inhibitor (STI) family include the presence of disulfide bridges --which are apparent in miraculin models-- and the inhibition of trypsin and chymotrypsin. Examples include MLPs extracted from ''Murraya koenigii'' and ''Vitis vinifera plants''. | ||
Since atomic-level structural data of miraculin is not available to date, A miraculin-like protein (MLP) homologous to miraculin extracted from Murraya koenigii will be used for protein visualization purposes. | Since atomic-level structural data of miraculin is not available to date, A miraculin-like protein (MLP) homologous to miraculin extracted from ''Murraya koenigii'' will be used for protein visualization purposes. | ||
== <h6><span style="color: #808080;"> MLP Extracted from ''Murraya koenigii'' (Heterodimer)</span></h6> == | == <h6><span style="color: #808080;"> MLP Extracted from ''Murraya koenigii'' (Heterodimer)</span></h6> == | ||
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<scene name='83/839322/His_residues_3iir/1'>Click here to view histidine residues </scene> | <scene name='83/839322/His_residues_3iir/1'>Click here to view histidine residues </scene> | ||
<StructureSection load=' | <StructureSection load='3iir' size='340' side='right' caption='Miraculin-Like Protein Extracted from ''Murraya koenigii'' (PDB code [[3iir]])' scene='' /> | ||
'''Miraculin-Like Protein Extracted from ''Murraya koenigii''''' | '''Miraculin-Like Protein Extracted from ''Murraya koenigii''''' | ||
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<StructureSection load=' | <StructureSection load='5yh4' size='340' side='right' caption='Structure of MLP Extracted from ''Vitis vinifera'' (monomer) (PDB code [[5yh4]])' scene='' /> | ||
'''Structure of MLP Extracted from ''Vitis vinifera'' (monomer)''' | '''Structure of MLP Extracted from ''Vitis vinifera'' (monomer)''' | ||
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== References == | == References == | ||
<references/> | <references/> | ||
[[Category:Topic Page]] | |||
