Optimization of Patterson Map Correlation for Electron Density and Its Square: Relationships for Phase Extension and Refinement
نویسندگان
چکیده
An objective function is described for optimization of Patterson map correlation for electron density and its square. The function provides excellent discrimination against all zero phases, and is analyzed to find relationships for phase extension and refinement. The objective function and phasing relationships can be calculated rapidly by convolution methods and are practical for application to macromolecular structure determination problems.
منابع مشابه
The PROTEIN system: Real-Space Techniques using Patterson and Fourier maps
Real-space techniques have been an important issue in the PROTEIN program system from its very beginning. In the field of molecular replacement the “real-space search methods” serve the correlation of maps for the exploration of non-crystallographic symmetry (Patterson self-rotation), positioning of known molecular models in unknown structures (cross-rotation, translation) both in Patterson and...
متن کاملAn envelope-based approach for direct phase determination of macromolecular structures.
An initial electron density distribution for a crystal structure may be directly derived from observed diffraction data by maximizing the product of the observed and calculated Patterson functions with respect to the electron density values within an envelope. This maximization problem may be formulated as an eigenvalue equation, in which potential electron density distributions are obtained as...
متن کاملImage encryption based on chaotic tent map in time and frequency domains
The present paper is aimed at introducing a new algorithm for image encryption using chaotic tent maps and the desired key image. This algorithm consists of two parts, the first of which works in the frequency domain and the second, in the time domain. In the frequency domain, a desired key image is used, and a random number is generated, using the chaotic tent map, in order to change the phase...
متن کاملتخمین احتمال بزرگی زمین‌لغزش‌های رخ‌داده در حوزه آبخیز پیوه‌ژن (استان خراسان رضوی)
Knowing the number, area, and frequency of landslides occurred in each area has a prominent role in the long-term evolution of area dominated by landslides and can be used for analyzing of susceptibility, hazard, and risk. In this regard, the current research is trying to consider identified landslides size probability in the Pivejan Watershed, Razavi Khorasan Province. In the first step, lands...
متن کاملStatistical density modification using local pattern matching
A method for improving crystallographic phases is presented that is based on the preferential occurrence of certain local patterns of electron density in macromolecular electron-density maps. The method focuses on the relationship between the value of electron density at a point in the map and the pattern of density surrounding this point. Patterns of density that can be superimposed by rotatio...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2007