To investigate the ability of a protein to accommodate potentially destabilizing amino acid substitutions, and also to investigate the steric requirements for catalysis, proline was substituted at different sites within the long alpha-helix that connects the amino-terminal and carboxyl-terminal domains of T4 lysozyme. Of the four substitutions attempted, three yielded folded, functional protein...

In this work, we use the formal definition of $k$-slant helix cite{ali2} to obtain the intrinsic equations as well as the position vector for emph{slant-slant helices} which a generalization of emph{general helices} and emph{slant helices}. Also, we present some characterizations theorems for $k$-slant helices and derived, in general form, the intrinsic equations for such curves. Thereafter, fr...

During the micro-drilling process of stainless steel, the wear, fracture, and breakage of the micro-drill easily occur. Micro-drill geometry parameters have significant influence on the drilling performance of the micro-drill. Nowadays, the helical point micro-drill is proposed and its improved drilling performance is validated by some researchers. In this study, to analyze the effect of geomet...

Many transcription factors have an a-helix that binds to DNA bases in a specific fashion. The DNA-binding geometry of these recognition helices varies substantially. We define a set of parameters to describe the binding geometry of recognition helices and analyze specific stereochemical elements that determine particular geometries. Because the convex surface of the helix must fit into the conc...

OBJECTIVES Implant design features such as macro- and micro-design may influence overall implant success. Limited information is currently available. Therefore, it is the purpose of this paper to examine these factors such as thread pitch, thread geometry, helix angle, thread depth and width as well as implant crestal module may affect implant stability. SEARCH STRATEGY A literature search wa...

Introduction: Hedera helix is an evergreen plant used in treatment of wounds in the Iranian folk medicine. One of the main stages in wound healing process is, the proliferative phase in which fibroblasts proliferate within the wounds and produce extracellular matrix. Collagen is the main constituent of extracellular matrix. So the aim of this study was to evaluate the effect of Hedera helix alc...

A recent theoretical model by Andersson et al. proposes that soft gluons order themselves in the form of a helix at the end of the QCD cascades. The Authors of the model present a measure of the rapidity-azimuthal angle correlation, which they call screwiness. We searched for such a signal in DELPHI data, and found no evidence for screwiness. ∗On leave of absence from University of Helsinki, Fi...

We propose to apply an "effective boundary condition" method the problem of chiral propulsion. For case a rotating helix moving through fluid at low Reynolds number, amounts replacing original (in limit small pitch) by cylinder, but with special kind partial slip conditions non-slip on helix. These are constructed reproduce far-field velocities problem, and defined few parameters (slipping leng...

In the title compound, C(15)H(16)S(2), the structure of the dithioalkyl chain is a helix with an all-cis conformation. The dihedral angle between the mean planes of the terminal aromatic rings is 74.60 (4)°. In the crystal structure, weak C-H⋯π inter-actions contribute to the stabilization of the packing.

We consider a unit speed curve α in Euclidean n-dimensional space E n and denote the Frenet frame by {V 1 ,. .. , V n }. We say that α is a cylindrical helix if its tangent vector V 1 makes a constant angle with a fixed direction U. In this work we give different characterizations of such curves in terms of their curvatures.