Orchestrating the Biosynthesis of an Unnatural Pyrrolysine Amino Acid for Its Direct Incorporation into Proteins Inside Living Cells

We here report the construction of an E. coli expression system able to manufacture an unnatural amino acid by artificial biosynthesis. This can be orchestrated with incorporation into protein by amber stop codon suppression inside a living cell. In our case an alkyne‐bearing pyrrolysine amino acid was biosynthesized and incorporated site‐specifically allowing orthogonal double protein labeling.     

Inverse problems for scattering by periodic structures

Suppose the 3-dimensional space is filled with three materials having dielectric constants ? ₁ above S ₁={x ₂=f ₁(x ₁), x ₃ arbitrary}, ? ₂ below S ₂ = {x ₂ =f ₂(x ₁), x ₃ arbitrary} and ? _o in {f ₂(x ₁) <x ₂ 1(x ₁), x ₃ arbitrary} where f ₁ f ₂ are periodic functions. Suppose for a plane wave incident on S ₁ from above we can measure the reflected and transmitted waves of the corresponding time-harmonic solution of the Maxwell equations, say at x ₂=±b,b large. To what extent can we infer from these measurements the location of the pair (S ₁, S ₂ ? In this paper, we establish a local stability: If ( $\tilde S_1 ,\tilde S_2$ ) is another pair of periodic curves “close” to (S ₁, S₂), then, for any δ>0, if the measurements for the two pairs are δ-close, then $\tilde S_1$ and $\tilde S_2$ are 0(δ)-close to S ₁ and S ₂, respectively.     

Uniform Convergence for Approximate Traveling Waves in Linear Reaction–Diffusion–Hyperbolic Systems

In this paper we study linear reaction–hyperbolic systems of the form , (i = 1, 2, ..., n) for x > 0, t > 0 coupled to a diffusion equation for p ₀ = p ₀(x, y, θ, t) with “near-equilibrium” initial and boundary data. This problem arises in a model of transport of neurofilaments in axons. The matrix (k _ij ) is assumed to have a unique null vector with positive components summed to 1 and the v _j are arbitrary velocities such that . We prove that as the solution converges to a traveling wave with velocity v and a spreading front, and that the convergence rate in the uniform norm is , for any small positive α.     

Crystallizable Polyphenylacetylene-Preparation and Solution Properties

The molecular weight distribution (MWD) of crystallizable polyphenylacetylene prepared near room temperature in the presence of ferric acetylacetonate and triethylaluminum was determined through use of fractions characterized by vapor pressure osmometry and gel permeation chromatography (GPC). The number- and weight-average molecular weights (M _n and M _w) are both less than the molecular weight corresponding to the maximum of the weight distribution function, which lacks a high molecular weight tail. M _wandM _n is less than is consistent with models allowing for chain termination characteristic of vinyl polymers. GPC elution volumes are much less than those characteristic of polystyrene of similar molecular weight, and the Mark-Houwink exponent is high (2.4 for M _v 4800 to 6800). These data indicate more rodlike behavior than for polystyrene of equivalent molecular weight. The MWD and other data suggest intramolecular chain termination, possibly associated with the molecule's tendency to form paramagnetic defect states.