Sandbox Reserved 774: Difference between revisions
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Most of the secondary structure elements of the monomer contribute residues involved in dimer contacts. A large part of the interface is formed by two projections from the core part of the monomer structure. The first projection is formed by the C-terminal end of strand B3, turn B3-B4, and the N-terminal end of strand B4, while the second is formed by strand B7. Together with strands B5 and B6 they form a barrel-like structure containing ten strands in which the component strands of the barrel locked together.<ref name=Shiva> Most importantly, strand b7 from each monomer interacts between strands b5 and b6 of the opposite monomer, which also extends the central sheet structure by two strands. Also, the two projections interact with residues from helices a1 and a2, turn a1 a2, turn a2 b2, and helices a3 and a4 of the opposite monomer. There are eight beta-strands, four <scene name='56/564050/Alpha_helices/2'>Alpha-helices</scene>, and ten turns. | Most of the secondary structure elements of the monomer contribute residues involved in dimer contacts. A large part of the interface is formed by two projections from the core part of the monomer structure. The first projection is formed by the C-terminal end of strand B3, turn B3-B4, and the N-terminal end of strand B4, while the second is formed by strand B7. Together with strands B5 and B6 they form a barrel-like structure containing ten strands in which the component strands of the barrel locked together.<ref name=Shiva> Most importantly, strand b7 from each monomer interacts between strands b5 and b6 of the opposite monomer, which also extends the central sheet structure by two strands. Also, the two projections interact with residues from helices a1 and a2, turn a1 a2, turn a2 b2, and helices a3 and a4 of the opposite monomer. There are eight beta-strands, four <scene name='56/564050/Alpha_helices/2'>Alpha-helices</scene>, and ten turns. | ||
[[Image:Hpa2_Active_Sites.jpg]] [[Image:Hpa2 Secondary Structure.jpg]] | [[Image:Hpa2_Active_Sites.jpg]] [[Image:Hpa2 Secondary Structure.jpg]]\ | ||
=Mechanism= | |||
Protein surfaces near the active site are characterized by a positive electrostatic potential.<ref name=Akhlaghi>Vetting, et al. "Structure and Functions of the GNAT Superfamily of Acetyltransferases." Arch Biochem Biophys 433(2004): Web. 26 Nov. 2013.</ref> In each structure there are several multi-chain carbonyl groups without hydrogen bonding partners in the active site. These could act in a proton transfer pathway by helping locate water molecules. Around the acetyl group, there exists a hydrophobic pocket which would stabilize the neutral charge while the substrate is bound to the enzyme once the amino group is deprotonated. | |||
=Mechanism= | =Mechanism= | ||
