Solid-State NMR Reveals Structural and Dynamical Properties of a Membrane Protein
 

http://pubs.acs.org/cgi-bin/abstract...ja069028m.html

Solid-State NMR Reveals Structural and Dynamical Properties of a Membrane-Anchored Electron-Carrier Protein, Cytochrome b₅
<aui auinm="Durr, U. H. N."> <aui auinm="Yamamoto, K."> <aui auinm="Im, S.-C."> <aui auinm="Waskell, L."> <aui auinm="Ramamoorthy, A."> <aug><aul></aul></aug></aui></aui></aui></aui></aui> <au>Ulrich H. N. Dürr,</au> <au>Kazutoshi Yamamoto,</au><au>Sang-Choul Im,</au><au>Lucy Waskell,and </au><au>Ayyalusamy Ramamoorthy*</au>
*ramamoor@umich.edu
<aff></aff>
<abs></abs>Abstract:
Cytochrome b₅ (cyt b₅) is a membrane-anchored electron-carrier protein containing a heme in its soluble domain. It enhances the enzymatic turnover of selected members of the cytochrome P450 superfamily of catabolic enzymes, localized in the endoplasmic reticulum of liver cells. Remarkably, its http://pubs.acs.org/images/gifchars/alpha.gif-helical membrane-anchoring domain is indispensable for the cyt b₅/cyt P450 interaction. Here, we present the first solid-state NMR studies on holo-cyt b₅ in a membrane environment, namely, macroscopically oriented DMPC/DHPC bicelles. We have presented approaches to selectively investigate different domains of the protein using spectral editing NMR techniques that utilize the unique motional properties of each domain. Two-dimensional ¹H-¹⁵N HIMSELF spectra showed PISA-wheel patterns reporting on the structure and dynamics of the membrane anchor of the protein.

the research work is pretty intresting.
can you post me the full article

Gelation mechanism and network structure of mixed solution of low- and high-acyl gell
 

Shingo Matsukawaa, , and Tokuko Watanabeb
aDepartment of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
bDepartment of Home Economics, Aoyama Gakuin Women's Junior College, 4-4-25 Shibuya, Shibuya-ku, Tokyo 150-8366, Japan
Received 26 September 2006; accepted 25 October 2006. Available online 8 December 2006.





Abstract

The gelation mechanism and the change of the network structure during cooling of the mixed solution of high-acyl (HA) and low-acyl (LA) gellan (containing 0.5% HA gellan and 0.5% LA gellan; hereafter called “mixed solution”) were elucidated on the basis of the results of dynamic viscoelasticity, circular dichroism (CD), and NMR measurements, which provide information about the network formation, the structural change due to random coil-double helix (C–H) transition, and the chain mobility of gellan, respectively. It was demonstrated that HA gellan chains in the mixed solution underwent C–H transition individually to form a network structure at the transition temperature for 1% HA gellan solution (75 °C), where storage modulus G′ and loss modulus G″ were steeply increased and the chain mobility of the HA gellan was restricted. The structural change of the HA gellan chains proceeded gradually with further cooling. At 25 °C, which is the C–H transition temperature for 1% LA gellan solution, LA gellan chains in the mixed solution formed a double helix, where G′ and G″ were slightly increased and the chain mobility of LA gellan was restricted. The results suggest that the double helix formation involves only the same kind of gellan chains even in the mixed solution, and that LA gellan chains decrease the mobility and promote the double helix formation of HA gellan chains, and vice versa.

Keywords: Low-acyl gellan; High-acyl gellan; Sol–gel transition; Random coil-double helix transition; Circular dichroism; NMR