Sandbox Reserved 1091: Difference between revisions

Line 48:

== Active site ==

'''The catalytic triad:''' The [http://en.wikipedia.org/wiki/Catalytic_triad~~.com~~ catalytic triad] of ASP is composed of '''Asp78''', '''His115''' and '''Ser336'''. These amino acids are the base is the active site of the protein, where the mode of action of the serine protease takes place. A peptide can be inserted in the space of the active site. There, the amino acids of <scene name='82/829344/Catalytic_triad/2'>the catalytic triad</scene> will interact together and the mechanism will lead to a cut in the polypeptide.

'''The catalytic triad:''' The [http://en.m.wikipedia.org/wiki/Catalytic_triad catalytic triad] of ASP is composed of '''Asp78''', '''His115''' and '''Ser336'''. These amino acids are the base is the active site of the protein, where the mode of action of the serine protease takes place. A peptide can be inserted in the space of the active site. There, the amino acids of <scene name='82/829344/Catalytic_triad/2'>the catalytic triad</scene> will interact together and the mechanism will lead to a cut in the polypeptide.

'''Mechanism:''' The mechanism is the following: The histidine will react with the serine and deprotonate it. '''The deprotonated hydroxyl group of the serine will act as a nucleophilic species''' and attack the carbon from the carbonyl function on the peptide. This will lead to the formation of a tetrahedral intermediate. Then, a second tetrahedral intermediate will be formed, but with the attack of a deprotonated water molecule. In the end, the regeneration of the active site will be done with the release of the peptide cut in two parts.

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ASP has its highest activity at pH 7,5 and loses it after heating at 60° for 10 minutes.

Experiments have been done in order to establish the sensitivity of ASP to proteases. In has been found that the ASP protease activity was strongly attenuated by serine protease inhibitors (DFP, ~~AEBSEF~~). Moreover, a soybean trypsin inhibitor was shown not to block the proteolytic action of ASP itself but could inhibit the vascular permeability enhancing activity that follows after injection of ASP into epithelial cells. <ref>Physicochemical and biological properties od an extracellular serine protease od Aeromonas sobria. Ritsuko Yokoyama, Yoshio Fujii et al., 2002 Japan.</ref>

Experiments have been done in order to establish the sensitivity of ASP to proteases. In has been found that the ASP protease activity was strongly attenuated by serine protease inhibitors ([http://en.m.wikipedia.org/wiki/Diisopropyl_fluorophosphate DFP], AEBSF). Moreover, a soybean trypsin inhibitor was shown not to block the proteolytic action of ASP itself but could inhibit the vascular permeability enhancing activity that follows after injection of ASP into epithelial cells. <ref>Physicochemical and biological properties od an extracellular serine protease od Aeromonas sobria. Ritsuko Yokoyama, Yoshio Fujii et al., 2002 Japan.</ref>

This experimental finding suggests that epithelial trypsin-like proteases mediate the reaction causing enhanced vascular permeability. It is likely that ASP stimulates the secretion and maturation of epithelial trypsin proteases, thus enhancing vascular permeability. ASP could stimulate the bradykinin-releasing pathway, thus stimulating mast cells to release histamine and further enhance the vascular permeability.

Sandbox Reserved 1091: Difference between revisions

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@@ Line 48: / Line 48: @@
 == Active site ==
-'''The catalytic triad:''' The [http://en.wikipedia.org/wiki/Catalytic_triad.com catalytic triad] of ASP is composed of '''Asp78''', '''His115''' and '''Ser336'''. These amino acids are the base is the active site of the protein, where the mode of action of the serine protease takes place. A peptide can be inserted in the space of the active site. There, the amino acids of <scene name='82/829344/Catalytic_triad/2'>the catalytic triad</scene> will interact together and the mechanism will lead to a cut in the polypeptide.
+'''The catalytic triad:''' The [http://en.m.wikipedia.org/wiki/Catalytic_triad catalytic triad] of ASP is composed of '''Asp78''', '''His115''' and '''Ser336'''. These amino acids are the base is the active site of the protein, where the mode of action of the serine protease takes place. A peptide can be inserted in the space of the active site. There, the amino acids of <scene name='82/829344/Catalytic_triad/2'>the catalytic triad</scene> will interact together and the mechanism will lead to a cut in the polypeptide.
 '''Mechanism:''' The mechanism is the following: The histidine will react with the serine and deprotonate it. '''The deprotonated hydroxyl group of the serine will act as a nucleophilic species''' and attack the carbon from the carbonyl function on the peptide. This will lead to the formation of a tetrahedral intermediate. Then, a second tetrahedral intermediate will be formed, but with the attack of a deprotonated water molecule. In the end, the regeneration of the active site will be done with the release of the peptide cut in two parts.
@@ Line 58: / Line 58: @@
 ASP has its highest activity at pH 7,5 and loses it after heating at 60° for 10 minutes.
-Experiments have been done in order to establish the sensitivity of ASP to proteases. In has been found that the ASP protease activity was strongly attenuated by serine protease inhibitors (DFP, AEBSEF). Moreover, a soybean trypsin inhibitor was shown not to block the proteolytic action of ASP itself but could inhibit the vascular permeability enhancing activity that follows after injection of ASP into epithelial cells. <ref>Physicochemical and biological properties od an extracellular serine protease od Aeromonas sobria. Ritsuko Yokoyama, Yoshio Fujii et al., 2002 Japan.</ref>
+Experiments have been done in order to establish the sensitivity of ASP to proteases. In has been found that the ASP protease activity was strongly attenuated by serine protease inhibitors ([http://en.m.wikipedia.org/wiki/Diisopropyl_fluorophosphate DFP], AEBSF). Moreover, a soybean trypsin inhibitor was shown not to block the proteolytic action of ASP itself but could inhibit the vascular permeability enhancing activity that follows after injection of ASP into epithelial cells. <ref>Physicochemical and biological properties od an extracellular serine protease od Aeromonas sobria. Ritsuko Yokoyama, Yoshio Fujii et al., 2002 Japan.</ref>
 This experimental finding suggests that epithelial trypsin-like proteases mediate the reaction causing enhanced vascular permeability. It is likely that ASP stimulates the secretion and maturation of epithelial trypsin proteases, thus enhancing vascular permeability. ASP could stimulate the bradykinin-releasing pathway, thus stimulating mast cells to release histamine and further enhance the vascular permeability.