Technical Documentation
A Reduced Representation Model of DNA: Analysis

Introduction
Force Field Assembly
Calculate


The Analyzer module currently defines ten functions for the analysis of the Reduced Representation DNA model. This module is in the Yup package at Yup.Models.rrDNAv1. The import statement is some variant of: from Yup.Models.rrDNAv1.Analyzer import *.


The ShowStretching(), ShowBending(), ShowTwisting() and ShowConstraints() functions report (to the standard output) the active terms of the Longitudinal Stretching, Roll and Tilt Rotations, Helical Twisting and a collection of constraints respectively. All functions take two arguments: the Model object of a rrDNAv1 model and optionally a file name in which case the report will be saved to the file instead of appearing on the standard output. See the following for the contents of these reports; the constraints report contains output from the Bonds term (see Stretching for format), Angles (see Bending) and SoftSphereX (see Constraints):

Stretching
Bending
Twisting
Constraints


The WriteArchive() function prints the coordinates of a chain to the standard output, in ARC3 format.

Function Name
Number of Arguments
Return Value
WriteArchive
3
-
Argument
Type
Preset Value
M
Model
-
limit
AtomMap
None
report
string
'' (blank string)

The M argument specifies a model which is assumed to contain exactly one DNA chain if the limit argument is at its default value of None. Otherwise, limit should be set to an AtomMap that encloses exactly one chain. The last argument has a default value of a blank string, which results in the output going to the standard output. This can be diverted to a file by setting the last argument to a string containing the name of the file.


The ShowInternal() function prints the internal coordinates of a chain to the standard output.

Function Name
Number of Arguments
Return Value
ShowInternal
2
-
Argument
Type
Preset Value
M
Model
-
report
string
'' (blank string)

The M argument specifies any model. The last argument has a default value of a blank string, which results in the output going to the standard output. This can be diverted to a file by setting the last argument to a string containing the name of the file.


The Writhe() function reports the writhing number for the specified model or a part of the model.

Function Name
Number of Arguments
Return Value
Writhe
2
-
Argument
Type
Preset Value
M
Model
-
limit
AtomMap
None

If the limit option results in selecting part of a DNA, the writhing number is calculated for the discontinuous chain. However, it is assumed that only one chain is supplied to the function.


The Link() function reports the linking number for the specified model or a part of the model.

Function Name
Number of Arguments
Return Value
Link
2
-
Argument
Type
Preset Value
M
Model
-
limit
AtomMap
None

The limit option should result in the selection of two equal-length and closed chains. Otherwise, the calculation will fail and even if results are available they will be completely meaningless.


The WriteParmTop() function outputs parmtop and coordinate files for AMBER.

Function Name
Number of Arguments
Return Value
WriteParmTop
2
-
Argument
Type
Preset Value
M
Model
-
prefix
string
'rrDNAv1'

The M argument specifies a rrDNAv1 model. The prefix argument provides a prefix for the names of the output files: the coordinate file will be named 'prefix.inpcrd' while the parmtop file will be named 'prefix.prmtop'.


The WritePDB() function outputs Protein Data Bank files.

Function Name
Number of Arguments
Return Value
WritePDB
2
-
Argument
Type
Preset Value
M
Model
-
filename
string
-

The M argument specifies a rrDNAv1 model. The filename argument specifies a name for the output file.


Service Functions

Manual
Introduction
Simplified RNA
Simplified DNA
Emmental
Virus Packing
Yup.scx Yup.vlat

Home
Information
News
User
Technical
Programmer
iYup
Download
Showcase
ETC