Cdc42Hs is a signal transduction protein that is involved in cytoskeletal growth and organization. We describe here the methyl side chain dynamics of three forms of (2)H,(13)C,(15)N-Cdc42Hs [GDP-bound (inactive), GMPPCP-bound (active), and GMPPCP/PBD46-bound (effector-bound)] from (13)C-(1)H NMR measurements of deuterium T(1) and T(1 rho) relaxation times. A wide variation in flexibility was observed throughout the protein, with methyl axis order parameters (S(2)(axis)) ranging from 0.2 to 0.4 (highly disordered) in regions near the PBD46 binding site to 0.8--1.0 (highly ordered) in some helices. The side chain dynamics of the GDP and GMPPCP forms are similar, with methyl groups on the PBD46 binding surface experiencing significantly greater mobility (lower S(2)(axis)) than those not on the binding surface. Binding of PBD46 results in a significant increase in the disorder and a corresponding increase in entropy for the majority of methyl groups. Many of the methyl groups that experience an increase in mobility are found in residues that are not part of the PBD46 binding interface. This entropy gain represents a favorable contribution to the overall entropy of effector binding and partially offsets unfavorable entropy losses such as those that occur in the backbone.
A research program has been initiated to formulate new strategies for efficient low-cost lignocellulosic biomass processing technologies for the production of biofuels. This article reviews results from initial research into lignocellulosic biomass structure, recalcitrance, and pretreatment. In addition to contributing towards a comprehensive understanding of lignocellulosic biomass, this work has contributed towards demonstrated optimizations of existing pretreatment methods, and the emergence of new possible pretreatment strategies that remain to be fully developed.
Using newly developed theoretical methods, we present preliminary
results for some calculated properties of
the cyclic peptide system
cyclo[(d-Ala-Glu-d-Ala-Gln)
m
=
1
-
4].
These calculations are motivated by the fact
that the
cyclo[(d-Ala-Glu-d-Ala-Gln)2]
cyclic peptide structure was the first cyclic peptide structure
synthesized
by an experimental group through a self-assembly process. In this
paper, we calculate the electronic structure
and vibrational mode properties of the isolated ring structures for
cyclo[(d-Ala-Glu-d-Ala-Gln)
m
=
1
-
4]
and of
the cyclic peptide nanotube system
cyclo[(d-Ala-Glu-d-Ala-Gln)2].
The HOMO−LUMO gap is wide (∼5.0
eV) yielding a transparent material with possibly unique bioelectronic
device applications. In addition, we
find that the C−O carbonyl stretch modes and the N−H amide-I
stretch modes of these isolated ring structures
to be highly localized at around 1773 and 3192
cm-1, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.