Use of designed metal-binding sites to study helix proximity in the lactose permease of Escherichia coli. 2. Proximity of helix IX (Arg302) with helix X (His322 and Glu325)

Biochemistry ◽  
1995 ◽  
Vol 34 (48) ◽  
pp. 15667-15670 ◽  
Author(s):  
Molly M. He ◽  
John Voss ◽  
Wayne L. Hubbell ◽  
H. Ronald Kaback
1994 ◽  
Vol 300 (2) ◽  
pp. 373-381 ◽  
Author(s):  
P Spencer ◽  
P M Jordan

Two distinct metal-binding sites, termed alpha and beta, have been characterized in 5-aminolaevulinic acid dehydratase from Escherichia coli. The alpha-site binds a Zn2+ ion that is essential for catalytic activity. This site can also utilize other metal ions able to function as a Lewis acid in the reaction mechanism, such as Mg2+ or Co2+. The beta-site is exclusively a transition-metal-ion-binding site thought to be involved in protein conformation, although a metal bound at this site only appears to be essential for activity if Mg2+ is to be bound at the alpha-site. The alpha- and beta-sites may be distinguished from one another by their different abilities to bind divalent-metal ions at different pH values. The occupancy of the beta-site with Zn2+ results in a decrease of protein fluorescence at pH 6. Occupancy of the alpha- and beta-sites with Co2+ results in u.v.-visible spectral changes. Spectroscopic studies with Co2+ have tentatively identified three cysteine residues at the beta-site and one at the alpha-site. Reaction with N-ethyl[14C]maleimide preferentially labels cysteine-130 at the alpha-site when Co2+ occupies the beta-site.


FEBS Letters ◽  
1996 ◽  
Vol 399 (1-2) ◽  
pp. 99-102 ◽  
Author(s):  
Svetlana Avaeva ◽  
Pavel Ignatov ◽  
Svetlana Kurilova ◽  
Tatjana Nazarova ◽  
Elena Rodina ◽  
...  

2010 ◽  
Vol 48 (6) ◽  
pp. 829-835 ◽  
Author(s):  
Bo-Young Yun ◽  
Yongbin Xu ◽  
Shunfu Piao ◽  
Nahee Kim ◽  
Jeong-Hyun Yoon ◽  
...  

Biochemistry ◽  
1994 ◽  
Vol 33 (2) ◽  
pp. 398-402 ◽  
Author(s):  
Bo Xu ◽  
Barton Trawick ◽  
George A. Krudy ◽  
Renee M. Phillips ◽  
Lei Zhou ◽  
...  

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