Nitric Oxide Synthase: Difference between revisions

Line 52:

<scene name='Sandbox_5/Nos_oxygenase_bh4/11'>H4B</scene> is a cofactor. NOS contains two molecules of <scene name='Sandbox_5/Begge_h4b/1'>H4B</scene>, one in each monomer. The active center forms ~~is a~~ part of the cavity already described. This cavity can be visualized as a <scene name='Nitric_oxide_synthase/Substratebinding_distal_pocket/2'>tunnel</scene>. Here H4B helps substrate interactions by lining the active-center tunnel and hydrogen bonding to the heme propionate amd to alfa7. Amd and alfa7 are two elements involved in L-Arg binding. This gives H4B the opportunity to play an important role in the control of subunit interactions and active-center formation. H4B is therefore more or less a structural cofactor and has a stabilizing effect. Its structural importance is further reconned to play a role in dimer formation (dimerization requires bound zinc ion along with H4B), and major conformational changes leading to the formation of the active site channelform<ref name="Raman">PMID:9875848</ref>.

<scene name='Sandbox_5/Nos_oxygenase_bh4/11'>H4B</scene> is a cofactor. NOS contains two molecules of <scene name='Sandbox_5/Begge_h4b/1'>H4B</scene>, one in each monomer. The active center forms part of the cavity already described. This cavity can be visualized as a <scene name='Nitric_oxide_synthase/Substratebinding_distal_pocket/2'>tunnel</scene>. Here H4B helps substrate interactions by lining the active-center tunnel and hydrogen bonding to the heme propionate amd to alfa7. Amd and alfa7 are two elements involved in L-Arg binding. This gives H4B the opportunity to play an important role in the control of subunit interactions and active-center formation. H4B is therefore more or less a structural cofactor and has a stabilizing effect. Its structural importance is further reconned to play a role in dimer formation (dimerization requires bound zinc ion along with H4B), and major conformational changes leading to the formation of the active site channelform<ref name="Raman">PMID:9875848</ref>.

[[image:H4b_hydrogenbindinger2.png|thumb|left|Hydrogenbondings in H4B binding site]]

The H4B is bound by hydrogen-bonds to several of the molecules surrounding it, including the substrate L-Arg. The substrate is H-bonded to the 4-keto group of pterin, and to one of the heme propionate groups ( the heme propionate group has two carboxylate oxygens in use for H-bonds). These oxygens are further H-bonded to the 4-keto group of pterin, through water, and directly to N(3) and NH2 on C (2)<ref name="Raman"/>. The overall picture of all the H-bonds can be seen by clicking on the figure on the left. [[image:mette.png|thumb|right|model for NOS oxygen activation]]

@@ Line 52: / Line 52: @@
 <applet load='2g6h' size='300' frame='true' align='right' caption='Tetrahydrobiopterin' />
-<scene name='Sandbox_5/Nos_oxygenase_bh4/11'>H4B</scene> is a cofactor. NOS contains two molecules of <scene name='Sandbox_5/Begge_h4b/1'>H4B</scene>, one in each monomer. The active center forms is a part of the cavity already described. This cavity can be visualized as a <scene name='Nitric_oxide_synthase/Substratebinding_distal_pocket/2'>tunnel</scene>. Here H<sub>4</sub>B helps substrate interactions by lining the active-center tunnel and hydrogen bonding to the heme propionate amd to alfa7. Amd and alfa7 are two elements involved in L-Arg binding. This gives H<sub>4</sub>B the opportunity to play an important role in the control of subunit interactions and active-center formation. H<sub>4</sub>B is therefore more or less a structural cofactor and has a stabilizing effect. Its structural importance is further reconned to play a role in dimer formation (dimerization requires bound zinc ion along with H<sub>4</sub>B), and major conformational changes leading to the formation of the active site channelform<ref name="Raman">PMID:9875848</ref>.
+<scene name='Sandbox_5/Nos_oxygenase_bh4/11'>H4B</scene> is a cofactor. NOS contains two molecules of <scene name='Sandbox_5/Begge_h4b/1'>H4B</scene>, one in each monomer. The active center forms part of the cavity already described. This cavity can be visualized as a <scene name='Nitric_oxide_synthase/Substratebinding_distal_pocket/2'>tunnel</scene>. Here H<sub>4</sub>B helps substrate interactions by lining the active-center tunnel and hydrogen bonding to the heme propionate amd to alfa7. Amd and alfa7 are two elements involved in L-Arg binding. This gives H<sub>4</sub>B the opportunity to play an important role in the control of subunit interactions and active-center formation. H<sub>4</sub>B is therefore more or less a structural cofactor and has a stabilizing effect. Its structural importance is further reconned to play a role in dimer formation (dimerization requires bound zinc ion along with H<sub>4</sub>B), and major conformational changes leading to the formation of the active site channelform<ref name="Raman">PMID:9875848</ref>.
 [[image:H4b_hydrogenbindinger2.png|thumb|left|Hydrogenbondings in H<sub>4</sub>B binding site]]
 The H<sub>4</sub>B is bound by hydrogen-bonds to several of the molecules surrounding it, including the substrate L-Arg. The substrate is H-bonded to the 4-keto group of pterin, and to one of the heme propionate groups ( the heme propionate group has two carboxylate oxygens in use for H-bonds). These oxygens are further H-bonded to the 4-keto group of pterin, through water, and directly to N(3) and NH<sub>2</sub> on C (2)<ref name="Raman"/>. The overall picture of all the H-bonds can be seen by clicking on the figure on the left. [[image:mette.png|thumb|right|model for NOS oxygen activation]]

Nitric Oxide Synthase: Difference between revisions

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools